ANN: eGenix mxODBC Connect Database Interface for Python 0.9.1 (beta)
ANNOUNCING eGenix.com mxODBC Connect Database Interface for Python Version 0.9.1 (beta) Our new client-server product for connecting Python applications to relational databases - on all major platforms This announcement is also available on our web-site for online reading: http://www.egenix.com/company/news/eGenix-mxODBC-Connect-0.9.1-beta.html INTRODUCTION The mxODBC Connect Database Interface for Python allows users to easily connect Python applications to all major databases on the market today in a highly portable and convenient way. This makes mxODBC Connect the ideal basis for writing cross-platform database programs and utilities in Python. mxODBC Connect extends our eGenix mx Python Extension series with a new client-server based product, that removes the need to install and configure ODBC drivers on the client side. This greatly simplifies setup and configuration of database driven client applications, while at the same time making the network communication between client and database server more efficient and more secure. * About Python: Python is an object-oriented Open Source programming language which runs on all modern platforms (http://www.python.org/). By integrating ease-of-use, clarity in coding, enterprise application connectivity and rapid application design, Python establishes an ideal programming platform for todays IT challenges. * About eGenix: eGenix is a consulting and software product company focused on providing professional quality services and products to Python users and developers (http://www.egenix.com/). HOW IT WORKS mxODBC Connect consists of two parts: a server installation which typically runs directly on the database server and a client Python package which is installed on the client machine that runs the Python application. The server part uses our high-performance database adapter mxODBC to connect to the database server. The client package communicates with the server part over a TCP/IP network, optionally using SSL encryption, advanced authentication and access controls - a feature that many database drivers fail to deliver. By separating the client application database interface from the server and using mxODBC Connect, you gain several benefits: * high portability and flexibility * centralized configuration and administration * added security * automatic fail-over * scalability * lower costs For more information, please have a look at the product page: http://www.egenix.com/products/python/mxODBCConnect/ NEWS mxODBC Connect 0.9 is a public beta release of our new mxODBC Connect product. If you would like to participate in the beta, please see our beta program page: http://www.egenix.com/products/python/mxODBCConnect/beta.html *SPECIAL OFFER* In order to make participation in the beta program more interesting for our users, we will be giving out *free discount coupons* to all participants who report back bugs in the product. DOWNLOADS The download archives as well as instructions for installation and configuration of the product can be found on the product page: http://www.egenix.com/products/python/mxODBCConnect/ ___ SUPPORT Commercial support for this product is available from eGenix.com. Please see http://www.egenix.com/services/support/ for details about our support offerings. -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, Jun 16 2008) Python/Zope Consulting and Support ...http://www.egenix.com/ mxODBC.Zope.Database.Adapter ... http://zope.egenix.com/ mxODBC, mxDateTime, mxTextTools ...http://python.egenix.com/ 2008-07-07: EuroPython 2008, Vilnius, Lithuania20 days to go Try mxODBC.Zope.DA for Windows,Linux,Solaris,MacOSX for free ! eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html
Decimals in python
Hello. New to using Python. Python automatically round off watver i calculate using the floor function. How wud i make the exact value appear? Tried out fabs() in the math library but still confused. Cud some1 elaborate on it. -- http://mail.python.org/mailman/listinfo/python-list
Re: newbie question: for loop within for loop confusion
On Jun 16, 2:35 pm, takayuki [EMAIL PROTECTED] wrote:
def hasnolet2(avoid):
fin = open('animals.txt')
for line in fin:
word = line.strip()
length = len(avoid)
x = 0
noprint = 0
while length -1 = x:
if avoid[x] in word:
noprint = noprint + 1
x = x + 1
if noprint == 0:
print word
There seems to be an indendation problem (presumably the code from
length = len(avoid) onwards should be inside the loop). But apart from
that, we can try to make this more 'pythonic'.
First, python has a 'for' statement that's usually better than using
while. We use the 'range' function that produces the numbers 0, 1, ...
length - 1, and x takes the value of these in turn.
Here's the last bit of your code rewritten like this:
noprint = 0
for x in range(length):
if avoid[x] in word:
noprint += 1
if noprint == 0:
print word
But better, rather than using 'x' as an index, we can loop over
letters in avoid directly. I've changed 'noprint' to be a boolean
'should_print' too here.
should_print = True
for letter in avoid:
if letter in word:
should_print = False
if should_print:
print word
We can eliminate 'should_print' completely, by using 'break' and
'else'. A break statement in a loop causes the loop to end. If the
loop doesn't break, the 'else' code is run when the loop's over.
for letter in avoid:
if letter in word:
break
else:
print word
This is almost the same as your original code, but the 'else' is
attached to the 'for' rather that the 'if'!
Finally, in Python 2.5 you can write this:
if not any(letter in word for letter in avoid):
print word
I think this is the best solution, as it's readable and short.
--
Paul Hankin
--
http://mail.python.org/mailman/listinfo/python-list
Re: os.walk Value Error?
En Sat, 14 Jun 2008 19:06:16 -0300, [EMAIL PROTECTED] escribió: I'm using os.walk as follows: (basedir, pathnames, files) = os.walk(results, topdown=True) and I'm getting the error: ValueError: too many values to unpack From my googling, that means: This is the standard message when Python tries to unpack a tuple into fewer variables than are in the tuple. From what I can see of the examples on the python site, I'm using it correctly. I have commas in my original code, and the results directory exists and is directly under the directory from which my script is run. Look the examples more carefully again - they don't use an assignment, but another Python statement... -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Decimals in python
[EMAIL PROTECTED] wrote: Hello. New to using Python. Python automatically round off watver i calculate using the floor function. How wud i make the exact value appear? Tried out fabs() in the math library but still confused. Cud some1 elaborate on it. If you're working with integers, the result will always be an integer: a = 10/3 print a 3 How ever if you add a float into the mix: a = 10/3.0 print a 3.3335 HTH -- http://mail.python.org/mailman/listinfo/python-list
Re: NoneType Error
En Sun, 15 Jun 2008 05:35:18 -0300, Maryam Saeedi [EMAIL PROTECTED] escribió: I am using a python program on a lot of different documents and for few of them I will get NoneType error. I just want to skip those files and continue for others, I do this without a problem for IndexError,TypeError,ValueError,NameError : try: except (IndexError,TypeError,ValueError,NameError): but when I add NoneType it gives the following error: except (NoneType,IndexError,TypeError,ValueError,NameError): NameError: name 'NoneType' is not defined and if I do not use the NoneType then it does not go through either and stops the program when I get to such a file. Is there another name that captures this error? NoneType is not an exception, but the type of the None object. Perhaps you're not interpreting correctly some error messages: x=None x() Traceback (most recent call last): File stdin, line 1, in module TypeError: 'NoneType' object is not callable (the exception raised is a TypeError; NoneType is part of the message). It appears that you want to catch all exceptions, just use Exception for that: try: ... except Exception: ... -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: HTML FORM AND PYTHON
Hi Diez, Thanx for the suggestion. I am checking if anything helpful I can find there. Regards, Subhabrata. Diez B. Roggisch wrote: [EMAIL PROTECTED] schrieb: Dear Members of the group, I have a small question, if you can help me to find the answer. I have one function: def add_string(n): print �Print Two strings� print �Print the First String� a1=raw_input(�PRINT THE FIRST STRING�) a2=raw_input(�PRINT THE SECOND STRING�) print �CONCATENATING THE TWO GIVEN STRINGS� a3=a1+a2 print �THE RESULT IS� print a3 Now, I have designed one HTML form which has two input fields for text and an output field for the result. I like to bind the python program into HTML form. i) Is there any way I can keep both my existing python code and HTML code and bind them? If any one can suggest with example. No. The above code works with user-interation at certain points of the program. That can't be (easily, and especially not with the above functionality) translated into the http-paradigm where each operation is embedded into a request/resonse-cycle, with the need for explicit or implicit state-keeping over these cycles. ii) Do I have to write the whole code in a way in python so that it would work the function as well as generate HTML form I am looking for? If any one can suggest with example. For this *trivial* example, I can only say: there isn't enough to be worth abstracting. iii) Is there any other way? Google python + webframeworks to find a bazillion discussions, opinions, examples. Diez -- http://mail.python.org/mailman/listinfo/python-list
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All girls boys in dating available in this web sit join him All girls boys in dating available in this web sit join him All girls boys in dating available in this web sit join him All girls boys in dating available in this web sit join him http://amigos.com/go/g979119-pct -- http://mail.python.org/mailman/listinfo/python-list
Re: Automatically restarting system calls?
Rhamphoryncus [EMAIL PROTECTED] writes: You might find a way to get SA_RESTART applied, but it won't work right for you. Python splits signal handlers into a top half and a bottom half - the bottom is in C, it's the real signal handler, and top is in python. To keep things sane for the top half, it delays until the interpreter is in a sane state (such as between bytecodes). If you used SA_RESTART the bottom half would still work, but the top would be delayed indefinitely until something else woke up the interpreter. In other words, your window likely won't redraw until the user types something or you print something. One possible way to handle this is by implementing a small signal handler in C. This signal handler can set the signal using SA_RESTART, getting rid of EINTR, at least for popular syscalls. In the signal handler it can simply write a byte into a pipe, the other end of which is monitored by the select() event loop. Python, presumably sleeping in select(), or about to do that, will immediately notice the signal by the pipe becoming readable. -- http://mail.python.org/mailman/listinfo/python-list
Changing Colors in gnuplot.py
Hello, Could some1 tell me how u could change the colours of the different lines that you have plotted while using gnuplot.py. Also how to change the background colour, line thickness etc. Thnx -- http://mail.python.org/mailman/listinfo/python-list
PEP 372 -- Adding an ordered directory to collections
Abstract
This PEP proposes an ordered dictionary as a new data structure for
the ``collections`` module, called odict in this PEP for short. The
proposed API incorporates the experiences gained from working with
similar implementations that exist in various real-world applications
and other programming languages.
Rationale
=
In current Python versions, the widely used built-in dict type does
not specify an order for the key/value pairs stored. This makes it
hard to use dictionaries as data storage for some specific use cases.
Some dynamic programming languages like PHP and Ruby 1.9 guarantee a
certain order on iteration. In those languages, and existing Python
ordered-dict implementations, the ordering of items is defined by the
time of insertion of the key. New keys are appended at the end, keys
that are overwritten and not moved.
The following example shows the behavior for simple assignments:
d = odict()
d['parrot'] = 'dead'
d['penguin'] = 'exploded'
d.items()
[('parrot', 'dead'), ('penguin', 'exploded')]
That the ordering is preserved makes an odict useful for a couple of
situations:
- XML/HTML processing libraries currently drop the ordering of
attributes, use a list instead of a dict which makes filtering
cumbersome, or implement their own ordered dictionary. This affects
ElementTree, html5lib, Genshi and many more libraries.
- There are many ordererd dict implementations in various libraries
and applications, most of them subtly incompatible with each other.
Furthermore, subclassing dict is a non-trivial task and many
implementations don't override all the methods properly which can
lead to unexpected results.
Additionally, many ordered dicts are implemented in an inefficient
way, making many operations more complex then they have to be.
- PEP 3115 allows metaclasses to change the mapping object used for
the class body. An ordered dict could be used to create ordered
member declarations similar to C structs. This could be useful, for
example, for future ``ctypes`` releases as well as ORMs that define
database tables as classes, like the one the Django framework ships.
Django currently uses an ugly hack to restore the ordering of
members in database models.
- Code ported from other programming languages such as PHP often
depends on a ordered dict. Having an implementation of an
ordering-preserving dictionary in the standard library could ease
the transition and improve the compatibility of different libraries.
Ordered Dict API
The ordered dict API would be mostly compatible with dict and existing
ordered dicts. (Note: this PEP refers to the Python 2.x dictionary
API; the transfer to the 3.x API is trivial.)
The constructor and ``update()`` both accept iterables of tuples as
well as mappings like a dict does. The ordering however is preserved
for the first case:
d = odict([('a', 'b'), ('c', 'd')])
d.update({'foo': 'bar'})
d
collections.odict([('a', 'b'), ('c', 'd'), ('foo', 'bar')])
If ordered dicts are updated from regular dicts, the ordering of new
keys is of course undefined again unless ``sort()`` is called.
All iteration methods as well as ``keys()``, ``values()`` and
``items()`` return the values ordered by the the time the key-value
pair was inserted:
d['spam'] = 'eggs'
d.keys()
['a', 'c', 'foo', 'spam']
d.values()
['b', 'd', 'bar', 'eggs']
d.items()
[('a', 'b'), ('c', 'd'), ('foo', 'bar'), ('spam', 'eggs')]
New methods not available on dict:
``odict.byindex(index)``
Index-based lookup is supported by ``byindex()`` which returns
the key/value pair for an index, that is, the position of a
key in the ordered dict. 0 is the first key/value pair, -1
the last.
d.byindex(2)
('foo', 'bar')
``odict.sort(cmp=None, key=None, reverse=False)``
Sorts the odict in place by cmp or key. This works exactly
like ``list.sort()``, but the comparison functions are passed
a key/value tuple, not only the value.
d = odict([(42, 1), (1, 4), (23, 7)])
d.sort()
d
collections.odict([(1, 4), (23, 7), (42, 1)])
``odict.reverse()``
Reverses the odict in place.
``odict.__reverse__()``
Supports reverse iteration by key.
Questions and Answers
=
What happens if an existing key is reassigned?
The key is not moved but assigned a new value in place. This is
consistent with existing implementations and allows subclasses to
change the behavior easily::
class movingcollections.odict):
def __setitem__(self, key, value):
self.pop(key, None)
odict.__setitem__(self, key, value)
What happens if keys appear multiple times in the list passed to the
constructor?
The same as for regular dicts: The latter item overrides the
former. This has the side-effect that the position of the
Re: Combining music or video files?
On 16 jun 2008, at 05:55, Jason Scheirer wrote: On Jun 15, 7:53 pm, John Salerno [EMAIL PROTECTED] wrote: Before I try this and destroy my computer :) I just wanted to see if this would even work at all. Is it possible to read a binary file such as an mp3 or an avi, put its contents into a new file, then read another such file and append its contents to this same new file as well, thereby making, for example, a single long video instead of two smaller ones? Thanks. This works with basic mpeg videos, but pretty much nothing else. You're going to need some video editing software. you can't just edit mpeg (including mp3)... mpeg is a stream. it sets a key frame for the first frame followed by motion vectors from the changes from that frame until the next keyframe. If you cut in the middle of the vectors the keyframe is lost and the vector frames don;t make any sense anymore. avi is not a video codec, it's a container like quicktime. so it depends... I come from a Mac background and use quicktime a lot. there are some basic editing features that quicktime can do. And Apple has a nice quicktime python module in OSX. I bet there's something for windows too... best thing to do is convert the video o a framesequence and the audio to an uncompressed format like wav or aiff then combine in quicktime or something in windows cheers, Arno -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
On Jun 16, 10:37 am, Armin Ronacher [EMAIL PROTECTED] wrote: Abstract This PEP proposes an ordered dictionary as a new data structure for the ``collections`` module, called odict in this PEP for short. The proposed API incorporates the experiences gained from working with similar implementations that exist in various real-world applications and other programming languages. +1, I have been waiting for an odict in the library for at least 5 years. Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: Removing inheritance (decorator pattern ?)
Diez B. Roggisch wrote: George Sakkis schrieb: I have a situation where one class can be customized with several orthogonal options. Currently this is implemented with (multiple) inheritance but this leads to combinatorial explosion of subclasses as more orthogonal features are added. Naturally, the decorator pattern [1] comes to mind (not to be confused with the the Python meaning of the term decorator). However, there is a twist. In the standard decorator pattern, the decorator accepts the object to be decorated and adds extra functionality or modifies the object's behavior by overriding one or more methods. It does not affect how the object is created, it takes it as is. My multiple inheritance classes though play a double role: not only they override one or more regular methods, but they may override __init__ as well. Here's a toy example: class Joinable(object): def __init__(self, words): self.__words = list(words) def join(self, delim=','): return delim.join(self.__words) class Sorted(Joinable): def __init__(self, words): super(Sorted,self).__init__(sorted(words)) def join(self, delim=','): return '[Sorted] %s' % super(Sorted,self).join(delim) class Reversed(Joinable): def __init__(self, words): super(Reversed,self).__init__(reversed(words)) def join(self, delim=','): return '[Reversed] %s' % super(Reversed,self).join(delim) class SortedReversed(Sorted, Reversed): pass class ReversedSorted(Reversed, Sorted): pass if __name__ == '__main__': words = 'this is a test'.split() print SortedReversed(words).join() print ReversedSorted(words).join() So I'm wondering, is the decorator pattern applicable here ? If yes, how ? If not, is there another way to convert inheritance to delegation ? Factory - and dynamic subclassing, as shown here: import random class A(object): pass class B(object): pass def create_instance(): superclasses = tuple(random.sample([A, B], random.randint(1, 2))) class BaseCombiner(type): def __new__(mcs, name, bases, d): bases = superclasses + bases return type(name, bases, d) class Foo(object): __metaclass__ = BaseCombiner return Foo() for _ in xrange(10): f = create_instance() print f.__class__.__bases__ Right now I see of course that I could have spared myself the whole __metaclass__-business and directly used type()... Oh well, but at least it worked :) Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Best way to make a number of tests against an object('s attributes) with absence of switch statement?
Phillip B Oldham a écrit :
What would be the optimal/pythonic way to subject an object to a
number of tests (based on the object's attributes) and redirect
program flow?
Say I had the following:
pets[0] = {'name': 'fluffy', 'species': 'cat', 'size': 'small'}
pets[1] = {'name': 'bruno', 'species': 'snake', 'size': 'small'}
pets[2] = {'name': 'rex', 'species': 'dog', 'size': 'large'}
What I'd like to do is loop through 'pets', and test each object. Some
of the tests I'd like to perform are:
Is the size 'small' and species not 'dog'?
Is the species 'cat' and name 'fluffy'?
Is the species not 'dog' or 'cat'?
In PHP I'd use a switch statement similar to the following:
foreach( $pets as $pet) {
switch(true) {
case ( $pet['size'] === 'small' $pet['species'] !== 'dog' ):
// do something
break;
// etc...
}
}
Now, I understand from a bit of googling that python doesn't have a
switch statement, and because of this people rely on python's
polymorphism.
You could also put it the other way round : Python doesn't have a switch
statement because peoples use polymorphism !-)
(nb : not that my reversed statement is in any way more true than
yours - but the fact is that procedural switch statement vs OO
polymorphic dispatch is not such a new topic...)
Thats great, but I've yet to come across a decent
example which make a click.
Any thoughts on how to proceed?
The braindead canonical OO solution would be to make a specific class
for each species each implementing it's own version of do_something().
The problem is that it would only dispatch on species, not other
attributes (size etc). Which is a inherent limitation of the canonical
OO type-based single dispatch mechanism.
A more elaborate canonical OO solution would be to use the visitor
pattern to overcome the single dispatch limitation.
A yet more elaborate (but way less canonical) solution is to use
predicate-based dispatch (cf Philip Eby's work).
Anyway, and while each dispatch mechanism (from basic branching to
complex predicate-based systems) has it's pros and cons, I'd first think
twice (or more) about whether my current dispatch problem has some
relative stability wrt/ the domain - IOW, it's structurally part of the
domain and won't change anytime soon - or if it's one of those ad-hoc
short-lived illogical business rule that is potentially subject to
unpredictable change any other day. Because the appropriate solution
really depends on this kind of considerations.
Now wrt/ your concrete example: truth is that, while expressed as a
switch statement, it's in fact really a if/elif/.../, since the
condition is not a constant (so you don't gain any performance gain from
using a switch). So the simplest translation in Python is to use an
if/elif/...
for pet in pets:
if pet['size'] == 'small' and pet['species'] !== 'dog':
// do something
elif (other complex condition):
// etc
--
http://mail.python.org/mailman/listinfo/python-list
Re: Hard to understand 'eval'
TheSaint a écrit : On 04:08, domenica 15 giugno 2008 [EMAIL PROTECTED] wrote: what's wrong with getattr(cp, nn) ? The learning curve to get into these programming ways. Does gettattr run the snippet passed in? Nope, it just does what the name implies. Considering that nn is a name of function, which will be called and (cfl, value) are the parameters to passed to that function. Everything in Python's an object (at least anything you can bind to a name), including functions and methods. Once you have a callable object, you just have to apply the call operator (parens) to call it. In your case, that would be: func = getattr(cc, nn, None) if callable(func): result = func(cfl, value) else: do_whatever_appropriate_here() I'll spend some bit on getattr use. Would be wise IMHO. -- http://mail.python.org/mailman/listinfo/python-list
Re: Hard to understand 'eval'
TheSaint a écrit : On 01:15, lunedì 16 giugno 2008 Calvin Spealman wrote: such as getattr(obj, methname)(a, b, c). Does this make sense? This is big enlightenment :) Thank you! :) I found problem with eval() when it comes to pass quoted strings. I circumvent that by encapsulating the strings in variable or tuple. The principle is to have a name which will refers a function somewhere in the program and to call that function, plus additional data passed in. In other word I'd expect something: function_list= ['add' ,'paint', 'read'] for func in function_list: func(*data) Can't work - function_list is a list of strings, not a list of functions. If the functions you intend to call are already bound to names in the current scope, you don't even need any extra lookup indirection: def add(*args): # code here from some_module import paint obj = SomeClass() read = obj.read functions = [add, paint, read] args = [1, 2] for func in functions: func(*args) I tried getattr, getattr is useful when you only have the name of the function/method/whatever attribute as a string. And a target object (hint: modules are objects too) of course - if the name lives either in the global or local namespace, you can access it by name using the dicts returned by resp. the globals() and locals() functions. HTH -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
Armin Ronacher [EMAIL PROTECTED] writes: This PEP proposes an ordered dictionary as a new data structure for the ``collections`` module, called odict in this PEP for short. A welcome addition. Since we're not proposing a built-in type, could we choose a name that is more explicit, and consistent with the types in 'collections' already. I'd prefer one of the following: collections.ordereddict collections.ordered_dict Other (minor) comments: The key is not moved but assigned a new value in place. This is consistent with existing implementations and allows subclasses to change the behavior easily:: class movingcollections.odict): Something is missing in the above line of code. It's invalid as-is, but I don't know which of the many possible replacements is intended. Why is there no ``odict.insert()``? Thank you for this design decision; I agree entirely that the correct solution is to resequence and create a new ordered dict from the result. A poorly performing example implementation of the odict written in Python is available: `odict.py http://dev.pocoo.org/hg/sandbox/raw-file/tip/ odict.py`_ This seems to be a victim of errant line-breaking, resulting in the wrong URL. -- \“The reason we come up with new versions is not to fix bugs. | `\ It's absolutely not.” —Bill Gates, 1995-10-23 | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: NoneType Error
Gabriel Genellina a écrit : En Sun, 15 Jun 2008 05:35:18 -0300, Maryam Saeedi [EMAIL PROTECTED] escribió: (snip) It appears that you want to catch all exceptions, just use Exception for that: try: ... except Exception: ... Hem... That's definitively *not* an a good advice here IMHO. A catch-all may be useful near a program's 'top-level' to handle any other unhandled exception in a more user-friendly way (ie : log the error, warns whoever is in charge, try to cleanly dispose of resources / data / whatever so we don't break anything, and display a nice and visible error message to the user), but anywhere else you really want to know *exactly* which exception(s) you're expecting to handle here and let the other propagate. -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
Armin Ronacher schrieb: Other implementations of ordered dicts in various Python projects or standalone libraries, that inspired the API proposed here, are: - `odict in Babel`_ - `OrderedDict in Django`_ - `The odict module`_ - `ordereddict`_ (a C implementation of the odict module) - `StableDict`_ - `Armin Rigo's OrderedDict`_ .. _odict in Babel: http://babel.edgewall.org/browser/trunk/babel/util.py?rev=374#L178 .. _OrderedDict in Django: http://code.djangoproject.com/browser/django/trunk/django/utils/datastructures.py?rev=7140#L53 .. _The odict module: http://www.voidspace.org.uk/python/odict.html .. _ordereddict: http://www.xs4all.nl/~anthon/Python/ordereddict/ .. _StableDict: http://pypi.python.org/pypi/StableDict/0.2 .. _Armin Rigo's OrderedDict: http://codespeak.net/svn/user/arigo/hack/pyfuse/OrderedDict.py I want add to this list my seqdict package, maybe the first implementation of an ordered dict in Python? http://home.arcor.de/wolfgang.grafen/Python/Modules/Modules.html I have never seen a real world dictionary which wasn't in order, so I ever felt the Python dictionary was not complete. I support the idea of an ordered dictionary in Python. Best regards Wolfgang -- http://mail.python.org/mailman/listinfo/python-list
Re: Checking each item in m.group()?
On Sun, 15 Jun 2008 18:15:38 -0700, Dennis Lee Bieber [EMAIL PROTECTED] wrote: I don't know quite what the reason for the sql = sql + ... is -- if you are trying to package more than one discrete statement into a single query you should be advised that not all adapters/DBMS support that function (I think one uses executescript() to signify multiple distinct statements. The script will go through about 3,000 lines of text, so I wanted to create a transaction with BEGIN/COMMIT. It seems like APSW (the simpler version of PySQLite) doesn't do transactions silently. A decent adapter should convert Python's None object into a proper DBMS Null. The adapter is also responsible for doing any needed quoting or escaping of the data supplied, hence no quoting of the placeholders! Thanks for the tip. However, after looking at the code you gave, I'm getting an error when running cur.execute(), so it is only ran once and the program exits: = import sys, re, apsw, os connection=apsw.Connection(test.sqlite) cursor=connection.cursor() textlines = [] textlines.append(123\titem1\titem2\titem3\titem4\t345\titem6) textlines.append(123\titem1\t\titem3\titem4\t345\titem6) p = re.compile(^(\d+)\t(.*?)\t(.*?)\t(.*?)\t(.*?)\t(\d+)\t(.+?)$) for line in textlines: m = p.search(line) if m: sql = 'INSERT INTO test (col1,col2,col3,col4,col5,col6,col7) VALUES (?,?,?,?,?,?,?);' cursor.execute(sql, tuple((c, None)[c == ] for c in m.groups())) File apsw.c, line 3518, in resetcursor apsw.ConstraintError: ConstraintError: not an error apsw.ConnectionNotClosedError: apsw.Connection on test.sqlite. The destructor has been called, but you haven't closed the connection. All connections must be explicitly closed. The SQLite database object is being leaked. cursor.execute(sql, tuple((c, None)[c == ] for c in m.groups())) connection.commit() connection.close(True) = I read the online sample for APSW, but didn't find what it could be. Any idea? Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: marshal.dumps quadratic growth and marshal.dump not allowing file-like objects
On Jun 15, 8:08 am, [EMAIL PROTECTED] wrote: Indeed. I (the OP) am using a production release which has the 1k linear growth. I am seeing the problems with ~5MB and ~10MB sizes. Apparently this will be improved greatly in Python 2.6, at least up to the 32MB limit. I've just fixed this for Py2.5.3 and Py2.6. No more quadratic behavior. Raymond -- http://mail.python.org/mailman/listinfo/python-list
ANN: eGenix mxODBC Connect Database Interface for Python 0.9.1 (beta)
ANNOUNCING eGenix.com mxODBC Connect Database Interface for Python Version 0.9.1 (beta) Our new client-server product for connecting Python applications to relational databases - on all major platforms This announcement is also available on our web-site for online reading: http://www.egenix.com/company/news/eGenix-mxODBC-Connect-0.9.1-beta.html INTRODUCTION The mxODBC Connect Database Interface for Python allows users to easily connect Python applications to all major databases on the market today in a highly portable and convenient way. This makes mxODBC Connect the ideal basis for writing cross-platform database programs and utilities in Python. mxODBC Connect extends our eGenix mx Python Extension series with a new client-server based product, that removes the need to install and configure ODBC drivers on the client side. This greatly simplifies setup and configuration of database driven client applications, while at the same time making the network communication between client and database server more efficient and more secure. * About Python: Python is an object-oriented Open Source programming language which runs on all modern platforms (http://www.python.org/). By integrating ease-of-use, clarity in coding, enterprise application connectivity and rapid application design, Python establishes an ideal programming platform for todays IT challenges. * About eGenix: eGenix is a consulting and software product company focused on providing professional quality services and products to Python users and developers (http://www.egenix.com/). HOW IT WORKS mxODBC Connect consists of two parts: a server installation which typically runs directly on the database server and a client Python package which is installed on the client machine that runs the Python application. The server part uses our high-performance database adapter mxODBC to connect to the database server. The client package communicates with the server part over a TCP/IP network, optionally using SSL encryption, advanced authentication and access controls - a feature that many database drivers fail to deliver. By separating the client application database interface from the server and using mxODBC Connect, you gain several benefits: * high portability and flexibility * centralized configuration and administration * added security * automatic fail-over * scalability * lower costs For more information, please have a look at the product page: http://www.egenix.com/products/python/mxODBCConnect/ NEWS mxODBC Connect 0.9 is a public beta release of our new mxODBC Connect product. If you would like to participate in the beta, please see our beta program page: http://www.egenix.com/products/python/mxODBCConnect/beta.html *SPECIAL OFFER* In order to make participation in the beta program more interesting for our users, we will be giving out *free discount coupons* to all participants who report back bugs in the product. DOWNLOADS The download archives as well as instructions for installation and configuration of the product can be found on the product page: http://www.egenix.com/products/python/mxODBCConnect/ ___ SUPPORT Commercial support for this product is available from eGenix.com. Please see http://www.egenix.com/services/support/ for details about our support offerings. -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, Jun 16 2008) Python/Zope Consulting and Support ...http://www.egenix.com/ mxODBC.Zope.Database.Adapter ... http://zope.egenix.com/ mxODBC, mxDateTime, mxTextTools ...http://python.egenix.com/ 2008-07-07: EuroPython 2008, Vilnius, Lithuania20 days to go Try mxODBC.Zope.DA for Windows,Linux,Solaris,MacOSX for free ! eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
Oh, very good, better late than never. This is my pure Python version, it performs get, set and del operations too in O(1): http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/498195 Working with C such data structure becomes much faster, because it can use true pointers. Then another data structure that may be named SortedDict can be created, that keeps items in their natural order (instead of the insertion order). Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list
String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
Summary: can't verify big O claim, how to properly time this?
On Jun 15, 2:34 pm, Terry Reedy [EMAIL PROTECTED] wrote:
Bart Kastermans [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
|I wrote a binary search tree in python, explaining as I was doing it
| how and why I did it. I am very interested in receiving comments on
| the code, process, and anything else that will improve my coding or
| writing.
|
| I wrote this all up in my blog at:
|
|http://kasterma.wordpress.com/2008/06/15/implementing-a-binary-search...
|
| The code of the class has been copied below, but the description of
| the process (mostly an attempt at approaching test driving development
| for as far as I understand the term) has not been copied.
|
| Any and all comments are appreciated.
|
| Best,
| Bart
|
| *** python code
|
|
| import re
|
| class BSTree:
|def __init__ (self, value = None):
|self.value = value
|self.left = None
|self.right = None
There are two possible approaches.
1. Define 1 tree class that is also used for subtrees -- what you did.
Complication: self.value of root node can be none, so you constantly
have to check self.value for None even though only possible for root node.
2. Define tree class and node class. This had other complications, but
removes that above and makes str easier. tree.str = '(' str(rootnode) ')'
and node.str= self.value '(' str(self.left) ')' '(' str(self.right) ')'.
If use '' instead of None, no conditionals are needed. (This might apply
partly to your version as well.) Or define class NullTree with a singleton
instance with no attributes and a str method returning '' and an inOrder
method yielding nothing. This would also eliminate the condifionals in the
inOrder method. Not sure what is best. With a good test suite, it is easy
to make sure alternative implementations 'work' before testing for speed.
Thanks for the idea. I would expect the separation to lead to
somewhat more
code, but all the checking the root code would be separated out in
the
tree class. The node class would be very smooth. I'll try this when
I have
some time (today I spend my alloted programming time on what is
below).
(also the comment about inOrder returning a generator was because I
tried to
figure it out, failed, and then got enough by doing it without yield.
I forgot
to bring my comment in line with my code. A generator
would certainly be nicer, and I'll work at understanding your
suggestion for
it.)
|def __str__ (self):
string appending is an O(n**2) operations. The usual idiom, applied here,
would be slist = ['('], slist.append(str(self.value)), return
''.join(slist). In other words, collect list of pieces and join at end.
This is interesting. I had never attempted to verify a big O
statement
before, and decided that it would be worth trying. So I wrote some
code to
collect data, and I can't find that it goes quadratic. I have the
graph
at
http://kasterma.wordpress.com/2008/06/16/complexity-of-string-concatenation/
It looks piecewise linear to me.
The code I used to collect the data is as follows:
*
import time
NUMBER = 100 # number of strings to concatenate at given length
JUMP = 500 # jump (and start length) of length of strings
END = 11# longest length string considered
def randomString (length):
returns a random string of letters from {a,b,c,d} of length
string =
for i in range (0,length):
string += choice (abcd)
return string
def randomStrings (number, length):
returns an array of number random strings all of length
array = []
for i in range (0, number):
array.append (randomString (length))
return array
TimingData = []
for length in range (JUMP, END, JUMP):
array1 = randomStrings (NUMBER, length)
array2 = randomStrings (NUMBER, length)
starttime = time.clock ()
for i in range (0, NUMBER):
string = array1 [i] + array2 [i]
endtime = time.clock ()
print length, length, done
TimingData.append ([length, 1000* (endtime-starttime)])
# to get a better looking graph multiply by 1000
sagefile = open ('stringConcatGraph.sage', w)
sagefile.write (points = + str (TimingData) + \n)
sagefile.write (graph = line (points)\n)
sagefile.write (graph.show ()\n)
sagefile.close ()
--
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help in soaplib
HI, I am trying to use the attachment object in soaplib. I am sending an attachment object and some other arguments and also receving an attachment object. So times I am able to receive the output image SVG file in my client side. But sometimes I am not. I am getting the following error message: - Traceback (most recent call last): File bifaclient.py, line 12, in module received=client.BiFa_analyser(file_to_send,[Mm]ouse,0.1,.,'all',False,True) File /Volumes/RAID1/xraid/Users/sukadeb/local/lib/python2.5/site-packages/soaplib-0.7.2dev_r27-py2.5.egg/soaplib/client.py, line 161, in __call__ payload, headers = from_soap(data) File /Volumes/RAID1/xraid/Users/sukadeb/local/lib/python2.5/site-packages/soaplib-0.7.2dev_r27-py2.5.egg/soaplib/soap.py, line 89, in from_soap root, xmlids = ElementTree.XMLID(xml_string) File string, line 89, in XMLID File string, line 86, in XML SyntaxError: no element found: line 1067, column 0 Due to firewall problems my server and client are in the same machine but in different directories. Kindly Help, Thank you in advance, Sukadeb. -- http://mail.python.org/mailman/listinfo/python-list
Context manager for files vs garbage collection
Hi
I was wondering when it was worthwil to use context managers for
file. Consider this example:
def foo():
t = False
for line in file('/tmp/foo'):
if line.startswith('bar'):
t = True
break
return t
What would the benefit of using a context manager be here, if any?
E.g.:
def foo():
t = False
with file('/tmp/foo') as f:
for line in f:
if line.startswith('bar'):
t = True
break
return t
Personally I can't really see why the second case would be much
better, I've got used to just relying on the garbage collector... :-)
But what is the use case of a file as a context manager then? Is it
only useful if your file object is large and will stay in scope for a
long time?
Regards
Floris
--
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Python GC does not work as it should be
See this piece of code:
/* API to invoke gc.collect() from C */
Py_ssize_t
PyGC_Collect(void)
{
Py_ssize_t n;
if (collecting)
n = 0; /* already collecting, don't do anything */
else {
collecting = 1;
n = collect(NUM_GENERATIONS - 1);
collecting = 0;
}
return n;
}
If a system exception raised when executing collect(xxx), collecting state
variable would never be reset and python GC will not works forever until the
application restarted. Perhaps it is a rare situation on normal usage, i
mean if 100% code written in python. I use python as an embedded engine on a
multithreaded server handling business process script which written in
python. Though at last i found my code that causing it and fixed, i still
think those code still has a potential problem on a long running process (as
server side scripting language). My workaround limited to implementation
with MSVC, I wrap those code in an exception trapper, and force to reset
collecting variable.
Salam,
-Jaimy.
--
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Re: Python GC does not work as it should be
On Mon, 16 Jun 2008 17:51:00 +0700, Jaimy Azle [EMAIL PROTECTED] wrote:
See this piece of code:
/* API to invoke gc.collect() from C */
Py_ssize_t
PyGC_Collect(void)
{
Py_ssize_t n;
if (collecting)
n = 0; /* already collecting, don't do anything */
else {
collecting = 1;
n = collect(NUM_GENERATIONS - 1);
collecting = 0;
}
return n;
}
If a system exception raised when executing collect(xxx), collecting state
variable would never be reset and python GC will not works forever until the
application restarted.
A system exception? What's that? C doesn't have exceptions.
Jean-Paul
--
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Re: Python GC does not work as it should be
Jean-Paul Calderone wrote: A system exception? What's that? C doesn't have exceptions. How could I determine it? I dont know GCC implementation, and others, but C on MSVC does have it. My application were not written in C, an exception raised was something like access violation at address on module python25.dll, and MSVC debugger shows collecting state were not reset (1), that is why GC would never happen. Salam, -Jaimy. -- http://mail.python.org/mailman/listinfo/python-list
Showing a point in Gnuploy.py
Hello. Could some1 tell me how i could display a specific point in gnuplot.py. Supposingly if i have a point of intersection (2,3). How can i show this on the graph? As in how can i write near the point of intersection the value :(2,3). Thnx -- http://mail.python.org/mailman/listinfo/python-list
Re: Notify of change to list
Paul - thank you very much for your help, it was much appreciated. I thought that this was the kind of thing I had to do. I also messed around with properties to try and solve this problem, but noticed a similar thing (ie, that changing a mutable attribute's element is different to rebinding it): when a propertied attribute is rebound, the set method is called as expected. However, when setting an element of a mutable like a list, the get method is called and the set is not. This seems to be a bit of a gotcha. I'm sure that calling the get method is justified in the terms of Python internals, but as a user it seems a little counter-intuitive. Without being an expert on language design, my first thought was that changing an element was a set operation. Here's a toy: class tobj(object): def __init__(self): self._x = [0,1,2,3,4,5,6] def setx(self, x): print At setx self._x = x def getx(self): print At getx return self._x d = property(getx, setx) a = tobj() print setting one element only a.d[1] = 3 print rebinding the attribute a.d = 99 which comes up with: setting one element only At getx rebinding the attribute At setx Does anyone know why it works like this? I would guess that to set one element, the attribute needs to be retrieved which means the get method is called. I also guess that only rebinding calls the set method which is why it isn't called here. Alan On Jun 13, 11:19 am, Paul Hankin [EMAIL PROTECTED] wrote: On Jun 13, 12:00 pm, Alan J.Salmoni [EMAIL PROTECTED] wrote: My question is how can my program be notified of a change to a class attribute that is a list? You can't. But you can replace lists inside your class with a list that notifies changes. Something like this: class NotifyingList(list): def __setitem__(self, i, v): print 'setting', i, 'to', v list.__setitem__(self, i, v) [[You'll likely need to redefine __setslice__, __delitem__, __delslice__, append and extend as well]]. x = NotifyingList([1, 2, 3]) x[1] = 4 setting 1 to 4 x [1, 4, 3] If users of your class are allowed to replace attributes with their own lists, you'll have to catch these and convert to NotifyingLists; and it may be somewhat messy. I hope this is useful to you. -- Paul Hankin -- http://mail.python.org/mailman/listinfo/python-list
SPAM
SPAM -- http://mail.python.org/mailman/listinfo/python-list
Re: Python GC does not work as it should be
On Mon, 16 Jun 2008 18:11:24 +0700, Jaimy Azle [EMAIL PROTECTED] wrote: Jean-Paul Calderone wrote: A system exception? What's that? C doesn't have exceptions. How could I determine it? I dont know GCC implementation, and others, but C on MSVC does have it. My application were not written in C, an exception raised was something like access violation at address on module python25.dll, and MSVC debugger shows collecting state were not reset (1), that is why GC would never happen. Ah, one of those. Thanks for the clarification. That basically means your program was supposed to crash. Instead, since you had visual studio around it handled the violation by popping up a dialog and giving you the choice to continue execution, which I guess you did. There's plenty of things other than that one static variable that can get messed up in this scenario. The access violation could easily come along with random memory corruption. Fixing just the GC to handle this doesn't mean your program will be able to keep running correctly. It's difficult or impossible to know what else has been put into an inconsistent state. The real fix is probably to track down what is causing the access violation. Once you fix that, the GC shouldn't need to be changed to account for this possibility, and you'll stop getting dialogs popping up from your app. :) Jean-Paul -- http://mail.python.org/mailman/listinfo/python-list
sorted or .sort() ?
My poor understanding is that the difference between `sorted(somelist, key=lambda x:...)` and `somelist.sort(lambda x,y...)` is that one returns a new list and the other sorts in-place. Does that mean that .sort() is more efficient and should be favored when you can (i.e. when you don't mind changing the listish object)? -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
-On [20080616 10:41], Armin Ronacher ([EMAIL PROTECTED]) wrote: This PEP proposes an ordered dictionary as a new data structure for the ``collections`` module, called odict in this PEP for short. I fully support adding this. In my work I have had to create this datatype a few times already. The suggested design choices seem logical to me. +1 -- Jeroen Ruigrok van der Werven asmodai(-at-)in-nomine.org / asmodai イェルーン ラウフロック ヴァン デル ウェルヴェン http://www.in-nomine.org/ | http://www.rangaku.org/ | GPG: 2EAC625B Of all that is to come, the Dream has just begun... -- http://mail.python.org/mailman/listinfo/python-list
Re: sorted or .sort() ?
Peter Bengtsson [EMAIL PROTECTED] writes: My poor understanding is that the difference between `sorted(somelist, key=lambda x:...)` and `somelist.sort(lambda x,y...)` is that one returns a new list and the other sorts in-place. Yes. Does that mean that .sort() is more efficient and should be favored when you can (i.e. when you don't mind changing the listish object)? No, it means you should choose the version that expresses what you actually want to do. Efficiency of the programmers — including the unknown number of programmers who will have to read the code after you write it — is in many cases a much more important criterion than efficiency of the CPU. People's time continues to be much more expensive than computer time, after all. -- \ Are you pondering what I'm pondering? Umm, I think so, | `\Brain, but what if the chicken won't wear the nylons? -- | _o__)_Pinky and The Brain_ | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: bpython - fancy Python shell
I couldn't get it work on Solaris (modified some lines for Python2.3). One reason was that I had to download pyreadline separately - I did than but now pyreadline requires either ironpython or a windows installation. Something is going wrong... Best regards Wolfgang Bob Farrell schrieb: I released this a while ago but did some work recently to fix some bugs so I thought I may as well post it here. To quickly summarise: In-line syntax highlighting Auto complete with suggestions as you type Pastebin stuff, save to file Rewind feature to jump back a line if you mess up (don't ask how it works, please ;) You can get it here: http://www.noiseforfree.com/bpython/ There's info about git repos and what have you there, and apparently it's also in some real distro repos, but I don't know the details. Oh, and you'll need pygments and pyparsing, and it doesn't work on Windows (heard good reports about it working fine on a Mac though). -- http://mail.python.org/mailman/listinfo/python-list
Zipping python modules
I've installed Python 2.5 on MSW and it works. I'm preparing it to run from a thumb drive so I can run applications by dropping them onto the python.exe or from command line/etc. It works but the size is quite large. I've compressed most of the executables with UPX even the dlls under site-packages, but is there a way I could compress the top-level 'lib' directory into a python.zip instead so save some space, and do I need the 'test' directory (which is about 10MB itself)? Brian Vanderburg II -- http://mail.python.org/mailman/listinfo/python-list
Re: newbie question: for loop within for loop confusion
takayuki [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] John: There were two inchworms because c is in inchworm so it shouldn't print. Thanks for your detailed description of the for loop. lol, I even sat there looking at the word and said to myself ok, it doesn't contain any of the four letters :) -- http://mail.python.org/mailman/listinfo/python-list
Re: newbie question: for loop within for loop confusion
takayuki [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
fin = open('animals.txt')
for line in fin:
You can write this as:
for line in open('animals.txt'):
#do stuff
Of course, you can't explicitly close the file this way, but that probably
doesn't matter. Another way, I think, is to wrap the for loops in this:
with open('animals.txt') as file:
#for loop stuff here
--
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Re: PEP 372 -- Adding an ordered directory to collections
This gets my +1, for what its worth.
I don't really see a good reason not to include the insert() method,
however. I don't see that it would complicate things much, if at all.
d = odict([('a', 42), ('b', 23)])
d.insert(1, ('c', 19))
d
collections.odict([('a', 42), ('c', 19), ('b', 23)])
On Jun 16, 2008, at 4:37 AM, Armin Ronacher wrote:
Abstract
This PEP proposes an ordered dictionary as a new data structure for
the ``collections`` module, called odict in this PEP for short. The
proposed API incorporates the experiences gained from working with
similar implementations that exist in various real-world applications
and other programming languages.
Rationale
=
In current Python versions, the widely used built-in dict type does
not specify an order for the key/value pairs stored. This makes it
hard to use dictionaries as data storage for some specific use cases.
Some dynamic programming languages like PHP and Ruby 1.9 guarantee a
certain order on iteration. In those languages, and existing Python
ordered-dict implementations, the ordering of items is defined by the
time of insertion of the key. New keys are appended at the end, keys
that are overwritten and not moved.
The following example shows the behavior for simple assignments:
d = odict()
d['parrot'] = 'dead'
d['penguin'] = 'exploded'
d.items()
[('parrot', 'dead'), ('penguin', 'exploded')]
That the ordering is preserved makes an odict useful for a couple of
situations:
- XML/HTML processing libraries currently drop the ordering of
attributes, use a list instead of a dict which makes filtering
cumbersome, or implement their own ordered dictionary. This affects
ElementTree, html5lib, Genshi and many more libraries.
- There are many ordererd dict implementations in various libraries
and applications, most of them subtly incompatible with each other.
Furthermore, subclassing dict is a non-trivial task and many
implementations don't override all the methods properly which can
lead to unexpected results.
Additionally, many ordered dicts are implemented in an inefficient
way, making many operations more complex then they have to be.
- PEP 3115 allows metaclasses to change the mapping object used for
the class body. An ordered dict could be used to create ordered
member declarations similar to C structs. This could be useful, for
example, for future ``ctypes`` releases as well as ORMs that define
database tables as classes, like the one the Django framework ships.
Django currently uses an ugly hack to restore the ordering of
members in database models.
- Code ported from other programming languages such as PHP often
depends on a ordered dict. Having an implementation of an
ordering-preserving dictionary in the standard library could ease
the transition and improve the compatibility of different libraries.
Ordered Dict API
The ordered dict API would be mostly compatible with dict and existing
ordered dicts. (Note: this PEP refers to the Python 2.x dictionary
API; the transfer to the 3.x API is trivial.)
The constructor and ``update()`` both accept iterables of tuples as
well as mappings like a dict does. The ordering however is preserved
for the first case:
d = odict([('a', 'b'), ('c', 'd')])
d.update({'foo': 'bar'})
d
collections.odict([('a', 'b'), ('c', 'd'), ('foo', 'bar')])
If ordered dicts are updated from regular dicts, the ordering of new
keys is of course undefined again unless ``sort()`` is called.
All iteration methods as well as ``keys()``, ``values()`` and
``items()`` return the values ordered by the the time the key-value
pair was inserted:
d['spam'] = 'eggs'
d.keys()
['a', 'c', 'foo', 'spam']
d.values()
['b', 'd', 'bar', 'eggs']
d.items()
[('a', 'b'), ('c', 'd'), ('foo', 'bar'), ('spam', 'eggs')]
New methods not available on dict:
``odict.byindex(index)``
Index-based lookup is supported by ``byindex()`` which returns
the key/value pair for an index, that is, the position of a
key in the ordered dict. 0 is the first key/value pair, -1
the last.
d.byindex(2)
('foo', 'bar')
``odict.sort(cmp=None, key=None, reverse=False)``
Sorts the odict in place by cmp or key. This works exactly
like ``list.sort()``, but the comparison functions are passed
a key/value tuple, not only the value.
d = odict([(42, 1), (1, 4), (23, 7)])
d.sort()
d
collections.odict([(1, 4), (23, 7), (42, 1)])
``odict.reverse()``
Reverses the odict in place.
``odict.__reverse__()``
Supports reverse iteration by key.
Questions and Answers
=
What happens if an existing key is reassigned?
The key is not moved but assigned a new value in place. This is
consistent with existing implementations and allows subclasses to
change the behavior easily::
class movingcollections.odict):
def
Re: Context manager for files vs garbage collection
Floris Bruynooghe a écrit :
Hi
I was wondering when it was worthwil to use context managers for
file. Consider this example:
def foo():
t = False
for line in file('/tmp/foo'):
if line.startswith('bar'):
t = True
break
return t
What would the benefit of using a context manager be here, if any?
E.g.:
def foo():
t = False
with file('/tmp/foo') as f:
for line in f:
if line.startswith('bar'):
t = True
break
return t
Personally I can't really see why the second case would be much
better, I've got used to just relying on the garbage collector... :-)
IIRC (please someone correct me if I'm wrong), proper release of file
resources as soon as the file object gets out of scope is not garanteed
in the language spec and is implementation dependant.
--
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Re: Combining music or video files?
Dennis Lee Bieber [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] On Sun, 15 Jun 2008 22:53:19 -0400, John Salerno [EMAIL PROTECTED] declaimed the following in comp.lang.python: Even the simplest format - WAV, which is normally uncompressed audio samples, is wrapped in layers of informational packets. snip other stuff!!! Yikes! Then what I'm reading from your post (and others) is no, I can't do it my way. ;) It *did* seem a little too easy, after all! -- http://mail.python.org/mailman/listinfo/python-list
Re: Iterate creating variables?
On Jun 13, 11:34 am, Reedick, Andrew [EMAIL PROTECTED] wrote: -Original Message- From: [EMAIL PROTECTED] [mailto:python- [EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, June 13, 2008 11:11 AM To: [EMAIL PROTECTED] Subject: Iterate creating variables? I have twenty-five checkboxes I need to create (don't ask): self.checkbox1 = ... self.checkbox2 = ... . . . self.checkbox25 = ... Right now, my code has 25 lines in it, one for each checkbox, since these are all variables. Is there a way to write a loop so that I can have fewer lines of code but still keep the variables? I've tried: for o in xrange(25): self.checkbox[o] = ... which didn't work, and for o in xrange(25): self.checkbox[''%d'%(o)] = ... which also didn't work. Both give the error message: Attribute error: Main.App has no attribute checkbox, which clearly indicates that I'm not keeping the variability aspect I want. Is there a way? I appreciate any and all answers! Either store the checkboxes in an array or hash/dictionary. If that's not practical, then You can use strings to build the code and use eval to execute the string as code. Ex: for i in range(10): code = %d + %d % (i, i) print eval(code) Don't do this. You want for idx in range(10): setattr(self, 'checkbox_%i' % idx) -- http://mail.python.org/mailman/listinfo/python-list
Re: Notify of change to list
I recently wanted to do the same kind of thing. See this tread: http://groups.google.com/group/comp.lang.python/browse_thread/thread/f27c3b7950424e1c for details on how to do it. -- http://mail.python.org/mailman/listinfo/python-list
Re: Zipping python modules
Brian Vanderburg II wrote: I've installed Python 2.5 on MSW and it works. I'm preparing it to run from a thumb drive so I can run applications by dropping them onto the python.exe or from command line/etc. It works but the size is quite large. I've compressed most of the executables with UPX even the dlls under site-packages, but is there a way I could compress the top-level 'lib' directory into a python.zip instead so save some space, and do I need the 'test' directory (which is about 10MB itself)? Brian Vanderburg II With thumb drives now being 2-4Gb what possible need would there be to worry about 10Mb? Remember by zipping things you are trading performance for size as well. -Larry -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
1. With the current dict, the following code
a = { A : 1, B : 2 }
b = { B : 2, A : 1 }
a==b evaluates to True. I assume that if these were odicts, this
would evaluate to False.
2. Will odict.byindex support slicing?
3. Will odict inherit from dict?
4. The current dict API (as of Python 2.5) is given by dir as:
['__class__', '__cmp__', '__contains__', '__delattr__', '__delitem__',
'__doc__', '__eq__', '__ge__', '__getattribute__', '__getitem__',
'__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__',
'__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__setitem__', '__str__', 'clear', 'copy',
'fromkeys', 'get', 'has_key', 'items', 'iteritems', 'iterkeys',
'itervalues', 'keys', 'pop', 'popitem', 'setdefault', 'update',
'values']
If I read your PEP correctly, you propose adding:
byindex
sort
reverse
__reverse__ (should be '__reversed__', to match list's reverse
iterator)
(This isn't really a question, your PEP was not completely explicit
about what odict's API would be, so I thought enumerating what dict
does currently might illuminate some other unresolved aspects of
odict. For instance, since odict is somewhat list-like in its notion
of keys and values, will pop support list-like popping as well as what
dict currently provides? Will you need a 'popbyindex' for the same
reason you need 'byindex', so that you have unambiguous lookup of
items by index vs. by key. Perhaps doing dir(list) will help you to
see other items to resolve/clarify.)
5. The more I think and write about this, the more struck I am at the
similarity of odict and the ParseResults class in pyparsing. For
instance, in ParseResults, there is also support for dict-style and
list-style item referencing, and I chose to restrict some cases so
that using [] notation would not be ambiguous. You might want to add
pyparsing.ParseResults as another reference of current odicts in the
wild (although ParseResults implements quite a bit of additional
behavior that would not be required or necessarily appropriate for
odict).
I vote +0 on this PEP - I've never personally needed an odict, but I
can see how some of the XML and ORM coding would be simplified by one.
-- Paul
(I could go either way on the name 'odict' or 'ordereddict'. Given
the desire for this to evenutally become a built-in, keep the name
short. On the other hand, collections already has 'defaultdict', so
is 'ordereddict' so bad?)
--
http://mail.python.org/mailman/listinfo/python-list
Who is using python-ldap with Python 1.5.x and 2.0-2.2?
HI! I'd like to hear from the Python community whether support for Python version prior to 2.3 is still needed in python-ldap. Please tell me which Python version you're using and why it'd be important for you to have python-ldap updates still supporting it. BTW: Actually older Python versions are not tested with recent python-ldap since at least two years. But I'd like to clearly decide on that. Ciao, Michael. -- http://mail.python.org/mailman/listinfo/python-list
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Re: Who is using python-ldap with Python 1.5.x and 2.0-2.2?
-On [20080616 15:55], Michael Ströder ([EMAIL PROTECTED]) wrote: I'd like to hear from the Python community whether support for Python version prior to 2.3 is still needed in python-ldap. Please tell me which Python version you're using and why it'd be important for you to have python-ldap updates still supporting it. Not that I use python-ldap at work, but our lowest Python version is 2.3 and we're working towards making 2.5 the default. Hopefully that helps you for versions used. :) -- Jeroen Ruigrok van der Werven asmodai(-at-)in-nomine.org / asmodai イェルーン ラウフロック ヴァン デル ウェルヴェン http://www.in-nomine.org/ | http://www.rangaku.org/ | GPG: 2EAC625B But the time has come when all good things shall pass... -- http://mail.python.org/mailman/listinfo/python-list
Re: sorted or .sort() ?
Peter Bengtsson [EMAIL PROTECTED] writes: Does that mean that .sort() is more efficient and should be favored when you can (i.e. when you don't mind changing the listish object)? Yes. Note that it's not the listish object, the sort method is implemented on actual lists, not on any sequence. -- http://mail.python.org/mailman/listinfo/python-list
RE: PEP 372 -- Adding an ordered directory to collections
:) Yes, I thought about that even as I was writing that post. But I also said, ParseResults implements quite a bit of additional behavior that would not be required or necessarily appropriate for odict. Even if odict existed, I think I would have needed ParseResults anyway (but using an odict internally might have simplified things for me, instead of the combined list and dict that I have now). -- Paul -Original Message- From: Shane Geiger [mailto:[EMAIL PROTECTED] Sent: Monday, June 16, 2008 9:20 AM To: Paul McGuire Cc: python-list@python.org Subject: Re: PEP 372 -- Adding an ordered directory to collections Paul, You seem to be contradicting yourself. You may have never needed an odict, yet you seem to have implemented one on your own. Maybe you needed one but did not realize it? Shane 5. The more I think and write about this, the more struck I am at the similarity of odict and the ParseResults class in pyparsing. For instance, in ParseResults, there is also support for dict-style and list-style item referencing, and I chose to restrict some cases so that using [] notation would not be ambiguous. You might want to add pyparsing.ParseResults as another reference of current odicts in the wild (although ParseResults implements quite a bit of additional behavior that would not be required or necessarily appropriate for odict). I vote +0 on this PEP - I've never personally needed an odict, but I can see how some of the XML and ORM coding would be simplified by one. -- Shane Geiger IT Director National Council on Economic Education [EMAIL PROTECTED] | 402-438-8958 | http://www.ncee.net Leading the Campaign for Economic and Financial Literacy -- http://mail.python.org/mailman/listinfo/python-list
Re: Removing inheritance (decorator pattern ?)
On Jun 16, 5:04 am, Diez B. Roggisch [EMAIL PROTECTED] wrote: Diez B. Roggisch wrote: George Sakkis schrieb: I have a situation where one class can be customized with several orthogonal options. Currently this is implemented with (multiple) inheritance but this leads to combinatorial explosion of subclasses as more orthogonal features are added. Naturally, the decorator pattern [1] comes to mind (not to be confused with the the Python meaning of the term decorator). However, there is a twist. In the standard decorator pattern, the decorator accepts the object to be decorated and adds extra functionality or modifies the object's behavior by overriding one or more methods. It does not affect how the object is created, it takes it as is. My multiple inheritance classes though play a double role: not only they override one or more regular methods, but they may override __init__ as well. Here's a toy example: class Joinable(object): def __init__(self, words): self.__words = list(words) def join(self, delim=','): return delim.join(self.__words) class Sorted(Joinable): def __init__(self, words): super(Sorted,self).__init__(sorted(words)) def join(self, delim=','): return '[Sorted] %s' % super(Sorted,self).join(delim) class Reversed(Joinable): def __init__(self, words): super(Reversed,self).__init__(reversed(words)) def join(self, delim=','): return '[Reversed] %s' % super(Reversed,self).join(delim) class SortedReversed(Sorted, Reversed): pass class ReversedSorted(Reversed, Sorted): pass if __name__ == '__main__': words = 'this is a test'.split() print SortedReversed(words).join() print ReversedSorted(words).join() So I'm wondering, is the decorator pattern applicable here ? If yes, how ? If not, is there another way to convert inheritance to delegation ? Factory - and dynamic subclassing, as shown here: import random class A(object): pass class B(object): pass def create_instance(): superclasses = tuple(random.sample([A, B], random.randint(1, 2))) class BaseCombiner(type): def __new__(mcs, name, bases, d): bases = superclasses + bases return type(name, bases, d) class Foo(object): __metaclass__ = BaseCombiner return Foo() for _ in xrange(10): f = create_instance() print f.__class__.__bases__ Right now I see of course that I could have spared myself the whole __metaclass__-business and directly used type()... Oh well, but at least it worked :) Diez Ok, I see how this would work (and it's trivial to make it cache the generated classes for future use) but I guess I was looking for a more mainstream approach, something that even a primitive statically typed language could run :) Even in Python though, I think of Runtime Type Generation like eval(); it's good that it exists but it should be used as a last resort. Also RTG doesn't play well with pickling. Since I don't have many useful subclasses so far, I'll stick with explicit inheritance for now but I'll consider RTG if the number of combinations becomes a real issue. George -- http://mail.python.org/mailman/listinfo/python-list
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Re: Removing inheritance (decorator pattern ?)
Ok, I see how this would work (and it's trivial to make it cache the generated classes for future use) but I guess I was looking for a more mainstream approach, something that even a primitive statically typed language could run :) Even in Python though, I think of Runtime Type Generation like eval(); it's good that it exists but it should be used as a last resort. Also RTG doesn't play well with pickling. Since I don't have many useful subclasses so far, I'll stick with explicit inheritance for now but I'll consider RTG if the number of combinations becomes a real issue. I wouldn't compare the usage of the type-constructor to eval. Python *is* a dynamic language, and it explicitly exposes parts of it's internals through things like metaclasses, descriptors and such. And your requirements simply can't be met by a traditional language. There it's either decoration or similar approaches, or nothing - especially you can't create objects that will survive static type-analysis with aggregated subclasses. You must lose that information through the delegation-nature of these recipes. Diez -- http://mail.python.org/mailman/listinfo/python-list
'string'.strip(chars)-like function that removes from the middle?
Greetings.
The strip() method of strings works from both ends towards the middle.
Is there a simple, built-in way to remove several characters from a
string no matter their location? (besides .replace() ;)
For example:
.strip -- 'www.example.com'.strip('cmowz.')
'example'
.??? -- --- 'www.example.com'.strip('cmowz.')
'exaple'
--
Ethan
--
http://mail.python.org/mailman/listinfo/python-list
Re: py2exe 0.6.8 released
Jimmy Retzlaff wrote: py2exe 0.6.8 released = py2exe is a Python distutils extension which converts Python scripts into executable Windows programs, able to run without requiring a Python installation. Console and Windows (GUI) applications, Windows NT services, exe and dll COM servers are supported. Changes in 0.6.8: * Support for relative imports. * Fix MemoryLoadLibrary to handle loading function addresses by ordinal numbers. Patch and test by Matthias Miller. * Using the options compressed=1, bundle_files=3, and zipfile=None at the same time now works; patch from Alexey Borzenkov. * Allow renaming of single-executable files; patch from Alexey Borzenkov. * Embedding icon resources into the image now works correctly even for ico files containing multiple images. * pyd files from different packages with the same filename no longer conflict. Patch from Grant Edwards. * There are new samples for the 'typelibs' support, including the new option of pre-generating a typelib and specifying the file as an input to py2exe. * The test suite is now included in the source distribution. Changes in 0.6.6: * Better support for Python 2.5. * Experimental support for 64-bit builds of Python on win64. * Better ISAPI support. * New samples for ISAPI and COM servers. * Support for new command-line styles when building Windows services. Changes in 0.6.5: * Fixed modulefinder / mf related bugs introduced in 0.6.4. This will be most evident when working with things like win32com.shell and xml.xpath. * Files no longer keep read-only attributes when they are copied as this was causing problems with the copying of some MS DLLs. Changes in 0.6.4: * New skip-archive option which copies the Python bytecode files directly into the dist directory and subdirectories - no archive is used. * An experimental new custom-boot-script option which allows a boot script to be specified (e.g., --custom-boot-script=cbs.py) which can do things like installing a customized stdout blackhole. See py2exe's boot_common.py for examples of what can be done. The custom boot script is executed during startup of the executable immediately after boot_common.py is executed. * Thomas Heller's performance improvements for finding needed modules. * Mark Hammond's fix for thread-state errors when a py2exe created executable tries to use a py2exe created COM DLL. Changes in 0.6.3: * First release assembled by py2exe's new maintainer, Jimmy Retzlaff. Code changes in this release are from Thomas Heller and Gordon Scott. * The dll-excludes option is now available on the command line. It was only possible to specify that in the options argument to the setup function before. The dll-excludes option can now be used to filter out dlls like msvcr71.dll or even w9xpopen.exe. * Fix from Gordon Scott: py2exe crashed copying extension modules in packages. Changes in 0.6.2: * Several important bugfixes: - bundled extensions in packages did not work correctly, this made the wxPython single-file sample fail with newer wxPython versions. - occasionally dlls/pyds were loaded twice, with very strange effects. - the source distribution was not complete. - it is now possible to build a debug version of py2exe. Changes in 0.6.1: * py2exe can now bundle binary extensions and dlls into the library-archive or the executable itself. This allows to finally build real single-file executables. The bundled dlls and pyds are loaded at runtime by some special code that emulates the Windows LoadLibrary function - they are never unpacked to the file system. This part of the code is distributed under the MPL 1.1, so this license is now pulled in by py2exe. * By default py2exe now includes the codecs module and the encodings package. * Several other fixes. Homepage: http://www.py2exe.org Download from the usual location: http://sourceforge.net/project/showfiles.php?group_id=15583 Enjoy, Jimmy - Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php Everyone, Thanks for all your hard work on py2exe, it is greatly appreciated. -Larry Bates -- http://mail.python.org/mailman/listinfo/python-list
Re: 'string'.strip(chars)-like function that removes from the middle?
On Jun 16, 2008, at 12:58 PM, Ethan Furman wrote:
Greetings.
The strip() method of strings works from both ends towards the middle.
Is there a simple, built-in way to remove several characters from a
string no matter their location? (besides .replace() ;)
For example:
.strip -- 'www.example.com'.strip('cmowz.')
'example'
.??? -- --- 'www.example.com'.strip('cmowz.')
'exaple'
re.sub('|'.join('cmowz.'), www.example.com)
'.exaple.'
--
Ethan
--
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--
http://mail.python.org/mailman/listinfo/python-list
Re: 'string'.strip(chars)-like function that removes from the middle?
Hi,
Greetings.
The strip() method of strings works from both ends towards the middle.
Is there a simple, built-in way to remove several characters from a
string no matter their location? (besides .replace() ;)
For example:
.strip -- 'www.example.com'.strip('cmowz.')
'example'
.??? -- --- 'www.example.com'.strip('cmowz.')
'exaple'
--
I don't see any string method to do that, but you can use a regexp :
re.sub('[cmowz.]', '', 'www.example.com')
'exaple'
--
Cédric Lucantis
--
http://mail.python.org/mailman/listinfo/python-list
Re: 'string'.strip(chars)-like function that removes from the middle?
Ethan Furman wrote:
Greetings.
The strip() method of strings works from both ends towards the middle.
Is there a simple, built-in way to remove several characters from a
string no matter their location? (besides .replace() ;)
For example:
.strip -- 'www.example.com'.strip('cmowz.')
'example'
.??? -- --- 'www.example.com'.strip('cmowz.')
'exaple'
--
Ethan
filter()
removeChars = ';j'
filter(lambda c: c not in removeChars, x)
'asdfklasdfkl'
or
a list comprehension
x=asdfjkl;asdfjkl;
''.join([c for c in x if c not in ';'])
'asdfjklasdfjkl'
-Larry
--
http://mail.python.org/mailman/listinfo/python-list
Re: String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
On Mon, Jun 16, 2008 at 4:34 AM, Bart Kastermans [EMAIL PROTECTED] wrote:
This is interesting. I had never attempted to verify a big O
statement
before, and decided that it would be worth trying. So I wrote some
code to
collect data, and I can't find that it goes quadratic. I have the
graph
at
http://kasterma.wordpress.com/2008/06/16/complexity-of-string-concatenation/
It looks piecewise linear to me.
I don't think there's any question that it's quadratic. Just look at
the C code, and you'll see that every time you concatenate the entire
string has to be copied. Remember that the copy code uses memcpy from
the C library, though, so it's quite fast. If you're not seeing it
for relatively small strings, it's probably that the major time
component is the Python looping construct, not the copy operation.
I tried it at lengths of multiples of 10, and it remained linear up
until 1E6. At 1E7, it appears to turn quadratic. I tried 1E8, but it
hasn't finished yet. I expect it to take the better part of an hour.
from timeit import Timer
a = Timer(a += 'a', a = '')
a.timeit(10)
6.9841280492255464e-006
a.timeit(100)
2.7936511287407484e-005
a.timeit(1000)
0.00043525084856810281
a.timeit(1)
0.0049266038004134316
a.timeit(10)
0.046758456731367914
a.timeit(100)
0.38496261396358022
a.timeit(1000)
20.320074199374631
Even though it doesn't become quadratic until 1E7, it's still up to an
order of magnitude faster to use str.join for smaller strings, though:
b = Timer(''.join(['a'] * 100))
b.timeit(1)
0.044094989726346512
-Ian
--
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Re: PEP 372 -- Adding an ordered directory to collections
I'm very happy to see this PEP. I have needed to use ordered dictionaries many times, and this has always felt to me like a surprising omission from Python. -- http://mail.python.org/mailman/listinfo/python-list
Re: 'string'.strip(chars)-like function that removes from the middle?
Le Monday 16 June 2008 18:58:06 Ethan Furman, vous avez écrit :
The strip() method of strings works from both ends towards the middle.
Is there a simple, built-in way to remove several characters from a
string no matter their location? (besides .replace() ;)
For example:
.strip -- 'www.example.com'.strip('cmowz.')
'example'
.??? -- --- 'www.example.com'.strip('cmowz.')
'exaple'
As Larry Bates said the python way is to use str.join, but I'd do it with a
genexp for memory saving, and a set to get O(1) test of presence.
to_remove = set('chars')
''.join(e for in string_ if e not in to_remove)
Note that this one will hardly be defeated by other idioms in python (even
regexp).
Using a genexp is free and a good practice, using a set, as it introduce one
more step, can be considered as premature optimisation and the one liner :
''.join(e for in string_ if e not in 'chars')
may be preferred.
--
_
Maric Michaud
--
http://mail.python.org/mailman/listinfo/python-list
Re: String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
On Mon, 16 Jun 2008 10:41:05 -0600, Ian Kelly [EMAIL PROTECTED] wrote: On Mon, Jun 16, 2008 at 4:34 AM, Bart Kastermans [EMAIL PROTECTED] wrote: This is interesting. I had never attempted to verify a big O statement before, and decided that it would be worth trying. So I wrote some code to collect data, and I can't find that it goes quadratic. I have the graph at http://kasterma.wordpress.com/2008/06/16/complexity-of-string-concatenation/ It looks piecewise linear to me. I don't think there's any question that it's quadratic. Just look at the C code, and you'll see that every time you concatenate the entire string has to be copied. It will depend what version of Python you're using and the *exact* details of the code in question. An optimization was introduced where, if the string being concatenated to is not referred to anywhere else, it will be re-sized in place. This means you'll probably see sub-quadratic behavior, but only with a version of Python where this optimization exists and only if the code can manage to trigger it. Jean-Paul -- http://mail.python.org/mailman/listinfo/python-list
Python-URL! - weekly Python news and links (Jun 16)
QOTW: The problem [with C++] is, I never feel like I'm programing the *problem*, I always feel like I'm programming the *language*. - Roy Smith Alternatives to the Decimal type: http://groups.google.com/group/comp.lang.python/browse_thread/thread/9cd6dae725268afb/ How to invert a dictionary: http://groups.google.com/group/comp.lang.python/browse_thread/thread/a8222b9dd036e4ef/ Why wxPython is not a standard module (and why some consider it unpythonic): http://groups.google.com/group/comp.lang.python/browse_thread/thread/fde7680a07b79cb0/ Why map(None, ...) behaves in the specific way it does: http://groups.google.com/group/comp.lang.python/browse_thread/thread/fe79adf209747a52/ Raw strings, backslashes, filenames, GUI input... A big confusion finally resolved: http://groups.google.com/group/comp.lang.python/browse_thread/thread/43940eb4de069f63/ A simple and suposedly safe eval() that isn't safe at all - malicious users can execute arbitrary code: http://groups.google.com/group/comp.lang.python/browse_thread/thread/40d765b5eedfb57/ How networks work - mostly off topic, but clearly and simply explained: http://groups.google.com/group/comp.lang.python/browse_thread/thread/e84dff684899c3f2/ Confusing the Google Data API, the services it access, and their licenses: http://groups.google.com/group/comp.lang.python/browse_thread/thread/b632eee9dc98b26c/ Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html PythonWare complements the digest you're reading with the marvelous daily python url http://www.pythonware.com/daily Mygale is a news-gathering webcrawler that specializes in (new) World-Wide Web articles related to Python. http://www.awaretek.com/nowak/mygale.html While cosmetically similar, Mygale and the Daily Python-URL are utterly different in their technologies and generally in their results. Just beginning with Python? This page is a great place to start: http://wiki.python.org/moin/BeginnersGuide/Programmers The Python Papers aims to publish the efforts of Python enthusiats: http://pythonpapers.org/ The Python Magazine is a technical monthly devoted to Python: http://pythonmagazine.com Readers have recommended the Planet sites: http://planetpython.org http://planet.python.org comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce Python411 indexes podcasts ... to help people learn Python ... Updates appear more-than-weekly: http://www.awaretek.com/python/index.html The Python Package Index catalogues packages. http://www.python.org/pypi/ The somewhat older Vaults of Parnassus ambitiously collects references to all sorts of Python resources. http://www.vex.net/~x/parnassus/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donate.html Kurt B. Kaiser publishes a weekly report on faults and patches. http://www.google.com/groups?as_usubject=weekly%20python%20patch Although unmaintained since 2002, the Cetus collection of Python hyperlinks retains a few gems. http://www.cetus-links.org/oo_python.html Python FAQTS http://python.faqts.com/ The Cookbook is a collaborative effort to capture useful and interesting recipes. http://aspn.activestate.com/ASPN/Cookbook/Python Many Python conferences around the world are in preparation. Watch this space for links to them. Among several Python-oriented RSS/RDF feeds available are http://www.python.org/channews.rdf http://bootleg-rss.g-blog.net/pythonware_com_daily.pcgi http://python.de/backend.php For more, see http://www.syndic8.com/feedlist.php?ShowMatch=pythonShowStatus=all The old
Re: 'string'.strip(chars)-like function that removes from the middle?
Ethan Furman wrote: The strip() method of strings works from both ends towards the middle. Is there a simple, built-in way to remove several characters from a string no matter their location? (besides .replace() ;) identity = .join(map(chr, range(256))) 'www.example.com'.translate(identity, 'cmowz.') 'exaple' Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: 'string'.strip(chars)-like function that removes from the middle?
On Jun 16, 10:09 am, Peter Otten [EMAIL PROTECTED] wrote: Ethan Furman wrote: The strip() method of strings works from both ends towards the middle. Is there a simple, built-in way to remove several characters from a string no matter their location? (besides .replace() ;) identity = .join(map(chr, range(256))) 'www.example.com'.translate(identity, 'cmowz.') 'exaple' And in Py2.6, you'll be able to simplify further: 'abcde'.translate(None, 'bd') 'ace' Raymond -- http://mail.python.org/mailman/listinfo/python-list
Re: String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
On Mon, Jun 16, 2008 at 11:09 AM, Jean-Paul Calderone [EMAIL PROTECTED] wrote: It will depend what version of Python you're using and the *exact* details of the code in question. An optimization was introduced where, if the string being concatenated to is not referred to anywhere else, it will be re-sized in place. This means you'll probably see sub-quadratic behavior, but only with a version of Python where this optimization exists and only if the code can manage to trigger it. AFAICT, PyString_Concat never calls _PyString_Resize. Am I looking in the wrong place? -Ian -- http://mail.python.org/mailman/listinfo/python-list
Re: sorted or .sort() ?
On Jun 16, 5:11 am, Peter Bengtsson [EMAIL PROTECTED] wrote: My poor understanding is that the difference between `sorted(somelist, key=lambda x:...)` and `somelist.sort(lambda x,y...)` is that one returns a new list and the other sorts in-place. Does that mean that .sort() is more efficient and should be favored when you can (i.e. when you don't mind changing the listish object)? Here's how sorted() works: def sorted(iterable, *args, **kwds): s = list(iterable) s.sort(*args, **kwds) return s So, sorted() runs at the same speed as list.sort() except for the step where the input gets copied. For list inputs, that extra time is trivial compared to the cost of actually doing the sort. I wouldn't worry about the negligible performance difference. Use whichever fits best in your program. Raymond -- http://mail.python.org/mailman/listinfo/python-list
Re: Removing inheritance (decorator pattern ?)
George Sakkis wrote:
I have a situation where one class can be customized with several
orthogonal options. Currently this is implemented with (multiple)
inheritance but this leads to combinatorial explosion of subclasses as
more orthogonal features are added. Naturally, the decorator pattern
[1] comes to mind (not to be confused with the the Python meaning of
the term decorator).
However, there is a twist. In the standard decorator pattern, the
decorator accepts the object to be decorated and adds extra
functionality or modifies the object's behavior by overriding one or
more methods. It does not affect how the object is created, it takes
it as is. My multiple inheritance classes though play a double role:
not only they override one or more regular methods, but they may
override __init__ as well. Here's a toy example:
I don't know if it will map to your actual problem, but here's a
variation of your toy code. I was thinking the Strategy pattern,
different classes have different initialisation strategies? But then you
could end up with as many Strategy classes as subclasses, I don't know.
(Also in vaguely similar territory -
http://bazaar.launchpad.net/~grflanagan/python-rattlebag/trunk/annotate/head:/src/template.py
)
class MetaBase(type):
def __init__(cls, name, bases, data):
cls.strategies = []
cls.prefixes = []
for base in bases:
print base
if hasattr(base, 'strategy'):
cls.strategies.append(base.strategy)
if hasattr(base, 'prefix'):
cls.prefixes.append(base.prefix)
super(MetaBase, cls).__init__(name, bases, data)
class Joinable(object):
__metaclass__ = MetaBase
strategy = list
prefix = ''
def __init__(self, words):
self._words = words
for strategy in self.strategies:
self._words = strategy(self._words)
def join(self, delim=','):
return '%s %s' % (' '.join(self.prefixes), delim.join(self._words))
class Sorted(Joinable):
strategy = sorted
prefix = '[sorted]'
class Reversed(Joinable):
strategy = reversed
prefix = '[reversed]'
class SortedReversed(Sorted, Reversed):
pass
class ReversedSorted(Reversed, Sorted):
pass
if __name__ == '__main__':
words = 'this is a test'.split()
print SortedReversed(words).join()
print ReversedSorted(words).join()
--
http://mail.python.org/mailman/listinfo/python-list
Re: bpython - fancy Python shell
Wolfgang Grafen [EMAIL PROTECTED]: I couldn't get it work on Solaris (modified some lines for Python2.3). If solaris doesn't have a readline library, you might try to compile gnu readline, and recompile python (also a chance to get the current version 2.5) One reason was that I had to download pyreadline separately - I did than but now pyreadline requires either ironpython or a windows installation. pyreadline is a windows-only thing. Since readline is a standard module on most unix systems and linux, there was no need to implement pyreadline for these systems. It would have been difficult anyway, since the windows console is completely different to unix consoles (which are fairly compatible to each other, a outcome of POSIX efforts). -- Freedom is always the freedom of dissenters. (Rosa Luxemburg) -- http://mail.python.org/mailman/listinfo/python-list
sqlite3 and Python 2.5.1
I have sqlite installed, but when I try to import sqlite3 I receive: Python 2.5.1 (r251:54863, Nov 3 2007, 02:54:36) [C] on sunos5 Type help, copyright, credits or license for more information. import sqlite3 Traceback (most recent call last): File stdin, line 1, in module ImportError: No module named sqlite3 Yet: # find /usr/local/python -name sqlite* -print /usr/local/python/lib/python2.5/sqlite3 # /opt/csw/bin/sqlite3 SQLite version 3.2.2 Enter .help for instructions sqlite What is missing? -- http://mail.python.org/mailman/listinfo/python-list
Re: String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
I found this article useful when dealing with strings in Python: http://www.skymind.com/~ocrow/python_string/ It may help squeeze some more time out of your code. 8-) Alex. -- http://mail.python.org/mailman/listinfo/python-list
Re: numpy: handling float('NaN') different in XP vs. Linux
Dan Bishop wrote: Python just uses the atof() function from the underlying C library. Some of them handle NaN's, and some of them don't. As a work around, how would I write this in list comprehension form: newlist=[] for i in range(len(v[1])): try: newlist.append(float(v[1][i])) except: newlist.append(-999.99) # or just nan possibly? -- View this message in context: http://www.nabble.com/numpy%3A-handling-float%28%27NaN%27%29-different-in-XP-vs.-Linux-tp17835502p17870333.html Sent from the Python - python-list mailing list archive at Nabble.com. -- http://mail.python.org/mailman/listinfo/python-list
Re: sqlite3 and Python 2.5.1
On Jun 17, 12:59 am, milan_sanremo [EMAIL PROTECTED] wrote: I have sqlite installed, but when I try to import sqlite3 I receive: Python 2.5.1 (r251:54863, Nov 3 2007, 02:54:36) [C] on sunos5 Type help, copyright, credits or license for more information. import sqlite3 Traceback (most recent call last): File stdin, line 1, in module ImportError: No module named sqlite3 Yet: # find /usr/local/python -name sqlite* -print /usr/local/python/lib/python2.5/sqlite3 # /opt/csw/bin/sqlite3 SQLite version 3.2.2 Enter .help for instructions sqlite What is missing? Did you, by chance, happened to compile your Python yourself? From what I see here: http://www.megasolutions.net/python/python-unix-install,-sqlite3-78710.aspx Python's source doesn't include the sqlite3 source, it only contains pysqlite interface, so when compiling python you need to get sqlite3 too. -- http://mail.python.org/mailman/listinfo/python-list
Re: Removing inheritance (decorator pattern ?)
On Jun 16, 1:49 pm, Gerard flanagan [EMAIL PROTECTED] wrote:
George Sakkis wrote:
I have a situation where one class can be customized with several
orthogonal options. Currently this is implemented with (multiple)
inheritance but this leads to combinatorial explosion of subclasses as
more orthogonal features are added. Naturally, the decorator pattern
[1] comes to mind (not to be confused with the the Python meaning of
the term decorator).
However, there is a twist. In the standard decorator pattern, the
decorator accepts the object to be decorated and adds extra
functionality or modifies the object's behavior by overriding one or
more methods. It does not affect how the object is created, it takes
it as is. My multiple inheritance classes though play a double role:
not only they override one or more regular methods, but they may
override __init__ as well. Here's a toy example:
I don't know if it will map to your actual problem, but here's a
variation of your toy code. I was thinking the Strategy pattern,
different classes have different initialisation strategies? But then you
could end up with as many Strategy classes as subclasses, I don't know.
(Also in vaguely similar territory
-http://bazaar.launchpad.net/~grflanagan/python-rattlebag/trunk/annota...
)
class MetaBase(type):
def __init__(cls, name, bases, data):
cls.strategies = []
cls.prefixes = []
for base in bases:
print base
if hasattr(base, 'strategy'):
cls.strategies.append(base.strategy)
if hasattr(base, 'prefix'):
cls.prefixes.append(base.prefix)
super(MetaBase, cls).__init__(name, bases, data)
class Joinable(object):
__metaclass__ = MetaBase
strategy = list
prefix = ''
def __init__(self, words):
self._words = words
for strategy in self.strategies:
self._words = strategy(self._words)
def join(self, delim=','):
return '%s %s' % (' '.join(self.prefixes), delim.join(self._words))
class Sorted(Joinable):
strategy = sorted
prefix = '[sorted]'
class Reversed(Joinable):
strategy = reversed
prefix = '[reversed]'
class SortedReversed(Sorted, Reversed):
pass
class ReversedSorted(Reversed, Sorted):
pass
if __name__ == '__main__':
words = 'this is a test'.split()
print SortedReversed(words).join()
print ReversedSorted(words).join()
This doesn't solve the original problem, the combinatorial explosion
of empty subclasses. At the end of the day, I'd like a solution that
uses a (mostly) flat, single-inheritance, hierarchy, allowing the
client say:
j = Joinable(words)
if sort:
j = Sorted(j)
if reverse:
j = Reversed(j)
...
print j.join()
George
--
http://mail.python.org/mailman/listinfo/python-list
Re: PEP 372 -- Adding an ordered directory to collections
On 16 juin, 10:37, Armin Ronacher [EMAIL PROTECTED] wrote: Abstract This PEP proposes an ordered dictionary as a new data structure for the ``collections`` module, called odict in this PEP for short. The proposed API incorporates the experiences gained from working with similar implementations that exist in various real-world applications and other programming languages. (snip) +1 insertion-ordered dicts are something I often need, and while there are usable workarounds, they either require boilerplate code, introduce external dependancies to (possibly unoptimised) code or make you reinvent the (square) wheel, all of which is (IMHO) below average Python's standard regarding data structures. -- http://mail.python.org/mailman/listinfo/python-list
Re: Configuration files
Does ConfigParser allow writing configuration changes also? Dennis Lee Bieber [EMAIL PROTECTED] schreef in bericht news:[EMAIL PROTECTED] On Sat, 14 Jun 2008 21:27:19 +0200, Robert [EMAIL PROTECTED] declaimed the following in comp.lang.python: What is the most Pythonic way to maintain a configuration file? Are there any libraries mimicking registry / ini file writing that many windows programming languages/environments offer? Uhm... Section 5.17 (at least, in v2.4.x) Library Reference: ConfigParser -- Wulfraed Dennis Lee Bieber KD6MOG [EMAIL PROTECTED] [EMAIL PROTECTED] HTTP://wlfraed.home.netcom.com/ (Bestiaria Support Staff: [EMAIL PROTECTED]) HTTP://www.bestiaria.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
On Mon, 16 Jun 2008 11:30:19 -0600, Ian Kelly [EMAIL PROTECTED] wrote: On Mon, Jun 16, 2008 at 11:09 AM, Jean-Paul Calderone [EMAIL PROTECTED] wrote: It will depend what version of Python you're using and the *exact* details of the code in question. An optimization was introduced where, if the string being concatenated to is not referred to anywhere else, it will be re-sized in place. This means you'll probably see sub-quadratic behavior, but only with a version of Python where this optimization exists and only if the code can manage to trigger it. AFAICT, PyString_Concat never calls _PyString_Resize. Am I looking in the wrong place? Yep. The optimization is done directly from the eval loop. Take a look at ceval.c, if you search for _PyString_Resize you should see it. Jean-Paul -- http://mail.python.org/mailman/listinfo/python-list
President Bush Meets Pope Before Heading to Paris
U.S. President George Bush has met with Pope Benedict at the Vatican, as he continues his week-long European trip. After his talks with the pontiff, Mr. Bush was traveling to Paris, France, where he is to give a speech later Friday on the strong relationship between the U.S. and Europe. U.S. National Security Advisor Stephen Hadley said Mr. Bush will urge European leaders to work even more closely with the U.S. to help bring peace to the Middle East. Mr. Hadley said the trans-Atlantic relationship has been strengthened by the current leaders in Italy, Britain, Germany, and France. The White House says Mr. Bush's speech will also commemorate the 60th anniversary of the Marshall Plan - the U.S. aid program that helped rebuild Europe after the devastation caused by World War II. The president and Mrs. Bush are then scheduled to have dinner with the French president and Mrs. Sarkozy at the Elysee Palace. Mr. Bush and Mr. Sarkozy hold formal talks on Saturday. On Thursday President Bush met with Italian Prime Minister Silvio Berlusconi and the two leaders agreed to to work together on trying to convince Iran to give up its uranium enrichment program. Mr. Berlusconi said Italy has a trading relation with Iran and knows that country from the inside. President Bush said he will consider Italy's request to join the five permanent U.N. Security Council members and Germany in working on the Iran nuclear issue. But Mr. Hadley said it is always a problem when a country's commercial ties clashes with its national security requirements. Mr. Bush's European trip will also take him to Britain and Northern Ireland. Earlier, he stopped in Germany and attended the annual U.S.- European Union summit in Slovenia. http://www.vaticans.org/index.php?/archives/1175-Pope-Benedict-XVI-hosted-US-President-George-W.-Bush-at-the-Vatican.html -- http://mail.python.org/mailman/listinfo/python-list
Re: py2exe 0.6.8 released
Being new on on Python (but otherwise experienced programmer this message triggered me to do the install. It looks like a nice way to do a comprehensive check of your system. When running one of the py2exe samples, located in C:\Python25\Lib\site-packages\py2exe\samples\singlefile\gui I got the following error when running the resulting executable: C:\Python25\Lib\site-packages\py2exe\samples\singlefile\gui\dist\test_wx.exe\zipextimporter.py:82: DeprecationWarning: The wxPython compatibility package is no longer automatically generated or actively maintained. Please switch to the wx package as soon as possible. Traceback (most recent call last): File test_wx.py, line 1, in module File zipextimporter.pyo, line 82, in load_module File wxPython\__init__.pyo, line 15, in module File zipextimporter.pyo, line 82, in load_module File wxPython\_wx.pyo, line 8, in module File zipextimporter.pyo, line 82, in load_module File wxPython\_misc.pyo, line 456, in module AttributeError: 'module' object has no attribute 'DateTime_GetNumberOfDaysinYear' I know of course the real error must be on the wx part of it all. I only have: - a python 2.5.2 install(msi) - a wxPython2.8-win32-unicode-2.8.7.1-py25.exe install - a py2exe-0.6.8.win32-py2.5.exeinstall. I have deleted C:\Python25\Lib\site-packages\wx-2.8-msw-unicode\wxPython because there indications that this is not needed, but other problems emerged. Any clues how to proceed next? Robert -- http://mail.python.org/mailman/listinfo/python-list
Re: String Concatenation O(n^2) (was: Re: Explaining Implementing a Binary Search Tree.)
On Mon, Jun 16, 2008 at 12:07 PM, Alex Elder [EMAIL PROTECTED] wrote: I found this article useful when dealing with strings in Python: http://www.skymind.com/~ocrow/python_string/ It may help squeeze some more time out of your code. 8-) Things seem to have changed since then. I'm finding that method 4 is about 15% faster than method 5. Whether the change is due to using a different Python version, processor, or operating system, I couldn't say. I used Python 2.5.2 on an Intel Core 2 at 2 GHz running Windows XP, SP2. -Ian -- http://mail.python.org/mailman/listinfo/python-list
How to request data from a lazily-created tree structure ?
Problem: - You have tree structure (XML-like) that you don't want to create 100% in memory, because it just takes too long (for instance, you need a http request to request the information from a slow distant site). - But you want to be able to request data from it, such has give me all nodes that are under a //foo/bar tree, and have a child with an baz attribute of value zzz. Question : Do you have any other idea to request data from a lazily-created tree structure ? And does it make sense to create a DOM-like structure and to use a generic XPath engine to request the tree ? (and does this generic XPath engine exist ?) The idea is to have the tree structure created on the fly (we are in python), only when the XPath engine requests the data. Hopefully the XPath engine will not request all the data from the tree (if the request is smart enough and does not contain **, for instance). Thanks -- http://mail.python.org/mailman/listinfo/python-list
vmware job vacancy!
A veteran engineer from VMWare Inc., Jeffrey, is being featured on jobirn.com on Monday Jun 16, from 9am to 5pm (PST.) He will chat with applicants who are interested in job openings in VMWare. He will identify qualified candidates and directly submit qualified candidates' resumes to hiring managers. Logon to http://jobirn.com and chat with Jeff. Jobirn.com is a job-referral company. It connects job applicants with insider employees in companies. Jobirn.com believes it gives qualified candidates higher opportunities to catch the attention of the right managers. Referrers, once featured, will usually make significant amount of bonus (Employee Referral Bonus) from his own company,if the recommended candidates are hired. -- http://mail.python.org/mailman/listinfo/python-list
Good cross-host IPC?
We've been using NetWorkSpaces
(http://www.ddj.com/web-development/21971) for IPC on programs running
on several different machines. Since it uses a central, shared server for
storing values, you don't have to write socket code in your various programs
to pass data back and forth.
For example, a program can request some work to be done by a random machine
on the network like so:
from nws.client import NetWorkSpace
space = NetWorkSpace('test')
space.store('value', 42)
ws.fetch('results')
43
...and a worker process can listen for work to do and return the results by
doing:
from nws.client import NetWorkSpace
space = NetWorkSpace('test')
value = space.fetch('value')
space.store('results', value + 1)
Since space.fetch() is a blocking call and the NetWorkSpaces server answers
requests in the order that they're received, this is a nice way to
coordinate a cluster.
This is pretty spiffy and works great in practice, but it feels like we're
the only people using it. Parallel Python lives in kind of the same problem
space, but not all of our code is easily bent to its will. Is there
another, more common way of doing this stuff?
Popularity isn't the most important thing in the world, but I like the warm
fuzzies of knowing that thousands of others are testing and using the same
project as we are.
--
Kirk Strauser
The Day Companies
--
http://mail.python.org/mailman/listinfo/python-list
Re: numpy: handling float('NaN') different in XP vs. Linux
John [H2O] wrote: Dan Bishop wrote: Python just uses the atof() function from the underlying C library. Some of them handle NaN's, and some of them don't. As a work around, how would I write this in list comprehension form: newlist=[] for i in range(len(v[1])): try: newlist.append(float(v[1][i])) except: newlist.append(-999.99) # or just nan possibly? from numpy import nan def nanfloat(x): if x.lower() == 'nan': return nan else: return float(x) newlist = [myfloat(x) for x in v[1]] -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
Re: newbie question: for loop within for loop confusion
On Jun 16, 7:17 am, Paul Hankin [EMAIL PROTECTED] wrote:
On Jun 16, 2:35 pm, takayuki [EMAIL PROTECTED] wrote:
def hasnolet2(avoid):
fin = open('animals.txt')
for line in fin:
word = line.strip()
length = len(avoid)
x = 0
noprint = 0
while length -1 = x:
if avoid[x] in word:
noprint = noprint + 1
x = x + 1
if noprint == 0:
print word
There seems to be an indendation problem (presumably the code from
length = len(avoid) onwards should be inside the loop). But apart from
that, we can try to make this more 'pythonic'.
First, python has a 'for' statement that's usually better than using
while. We use the 'range' function that produces the numbers 0, 1, ...
length - 1, and x takes the value of these in turn.
Here's the last bit of your code rewritten like this:
noprint = 0
for x in range(length):
if avoid[x] in word:
noprint += 1
if noprint == 0:
print word
But better, rather than using 'x' as an index, we can loop over
letters in avoid directly. I've changed 'noprint' to be a boolean
'should_print' too here.
should_print = True
for letter in avoid:
if letter in word:
should_print = False
if should_print:
print word
We can eliminate 'should_print' completely, by using 'break' and
'else'. A break statement in a loop causes the loop to end. If the
loop doesn't break, the 'else' code is run when the loop's over.
for letter in avoid:
if letter in word:
break
else:
print word
This is almost the same as your original code, but the 'else' is
attached to the 'for' rather that the 'if'!
Finally, in Python 2.5 you can write this:
if not any(letter in word for letter in avoid):
print word
I think this is the best solution, as it's readable and short.
Alternatively, you could use sets:
if not(set(word) set(avoid)):
print word
(parentheses added for clarity.)
--
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Re: Simple and safe evaluator
Okay guys. I have the _ast based safe eval installed and working in my
program. It appears to be working just fine. Thanks for the help.
Now, a few more questions:
1. I see that _ast is a 2.5 module?? So, for folks using my code with
2.5 I could do something like this:
# I've got some imports here to look after the error() and warning()
funcs
emsg_done = 0
etx =
def unsafe_eval(s):
safe eval for python 2.5 (lacks _ast)
global emsg_done
if not emsg_done:
warning(You are using an unsafe eval() function. Please
upgrade to Python version 2.5 or greater.)
emsg_done=1
# need error trap here as well ...
return eval(s, {__builtins__:None}, {} )
def safe_eval(text):
similar to eval, but only works on numerical values.
global etx
try:
ast = compile(text, string, 'eval', _ast.PyCF_ONLY_AST)
except:
error(Expression error in '%s' % text)
etx = text # for error reporting, bvdp
return _traverse(ast.body)
try:
import _ast
num_eval = safe_eval
except:
num_eval = unsafe_eval
# rest of matt's ast code follows.
Which appears to do the following: if there isn't an _ast module we just
define an alternate, not-so-safe, function and warn the user; otherwise
we use the safe version. I'm a bit uncomfortable with the import _ast
being after the function which uses the code, but it seems to work.
2. I thought I'd be happy with * / + -, etc. Of course now I want to add
a few more funcs like int() and sin(). How would I do that?
Thanks. This is looking very nice indeed.
Bob.
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Re: 32 bit or 64 bit?
On Jun 16, 12:57 am, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: On Jun 15, 11:30 pm, Christian Heimes [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: I have a physical system set up in which a body is supposed to accelerate and to get very close to lightspeed, while never really attaining it. After approx. 680 seconds, Python gets stuck and tells me the object has passed lightspeed. I put the same equations in Mathematica, again I get the same mistake around 680 seconds. So I think, I have a problem with my model! Then I pump up the WorkingPrecision in Mathematica to about 10. I run the same equations again, and it works! At least for the first 10,000 seconds, the object does not pass lightspeed. I concluded that I need Python to work at a higher precision. I conclude that your algorithm is numerical wrong. It probably suffers from a rounding error which increases itself in every iteration. Increasing the precision doesn't solve your problem. It's only going to hide the fact that your algorithm doesn't do its job. Please don't get me wrong. I don't want to imply that you are an idiot who doesn't know what he is doing. :] Most likely you weren't taught how to write numerical sound algorithms. Let's all blame your school or university. *g* Numerics is a complex area and it took me more than a year to learn the basics. Don't be embarrassed! I'll try to read some. But I used mpmath to pump up the precision in my code, and now the problem doesn't happen. So I think it's okay for now. Thanks to all contributors for your advice. Ram Rachum. -- http://mail.python.org/mailman/listinfo/python-list
Re: sqlite3 and Python 2.5.1
milan_sanremo wrote: I have sqlite installed, but when I try to import sqlite3 I receive: Python 2.5.1 (r251:54863, Nov 3 2007, 02:54:36) [C] on sunos5 Type help, copyright, credits or license for more information. import sqlite3 Traceback (most recent call last): File stdin, line 1, in module ImportError: No module named sqlite3 Yet: # find /usr/local/python -name sqlite* -print /usr/local/python/lib/python2.5/sqlite3 # /opt/csw/bin/sqlite3 SQLite version 3.2.2 Enter .help for instructions sqlite What is missing? You compiled Python yourself. During that, the SQLite3 header files could not be found, so the sqlite3 module was not compiled/installed. -- Gerhard -- http://mail.python.org/mailman/listinfo/python-list
Re: How to request data from a lazily-created tree structure ?
méchoui schrieb: Problem: - You have tree structure (XML-like) that you don't want to create 100% in memory, because it just takes too long (for instance, you need a http request to request the information from a slow distant site). - But you want to be able to request data from it, such has give me all nodes that are under a //foo/bar tree, and have a child with an baz attribute of value zzz. Question : Do you have any other idea to request data from a lazily-created tree structure ? And does it make sense to create a DOM-like structure and to use a generic XPath engine to request the tree ? (and does this generic XPath engine exist ?) The idea is to have the tree structure created on the fly (we are in python), only when the XPath engine requests the data. Hopefully the XPath engine will not request all the data from the tree (if the request is smart enough and does not contain **, for instance). Generic XPath works only with a DOM(like) structure. How else would you e.g. evaluate an expression like foo[last()]? So if you really need lazy evaluation, you will need to specifically analyze the query of interest and see if it can be coded in a way that allows to forget as much of the tree as possible, or even better not query it. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Simple and safe evaluator
On Jun 16, 4:47 pm, bvdp [EMAIL PROTECTED] wrote:
2. I thought I'd be happy with * / + -, etc. Of course now I want to add
a few more funcs like int() and sin(). How would I do that?
For the builtin eval, just populate the globals dict with the names
you want to make available:
import math
globs = {'__builtins__' : None}
# expose selected builtins
for name in 'True False int float round abs divmod'.split():
globs[name] = eval(name)
# expose selected math constants and functions
for name in 'e pi sqrt exp log ceil floor sin cos tan'.split():
globs[name] = getattr(math,name)
return eval(s, globs, {})
The change to the _ast version is left as an exercise to the reader ;)
George
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Re: sorted or .sort() ?
Ben Finney [EMAIL PROTECTED] wrote: Peter Bengtsson [EMAIL PROTECTED] writes: My poor understanding is that the difference between `sorted(somelist, key=lambda x:...)` and `somelist.sort(lambda x,y...)` is that one returns a new list and the other sorts in-place. Yes. Does that mean that .sort() is more efficient and should be favored when you can (i.e. when you don't mind changing the listish object)? No, it means you should choose the version that expresses what you actually want to do. Efficiency of the programmers ??? including the unknown number of programmers who will have to read the code after you write it ??? is in many cases a much more important criterion than efficiency of the CPU. People's time continues to be much more expensive than computer time, after all. Good advice with one caveat: sorted() was only introduced in python 2.4 so if your code must run on earlier versions then use list.sort() -- Nick Craig-Wood [EMAIL PROTECTED] -- http://www.craig-wood.com/nick -- http://mail.python.org/mailman/listinfo/python-list
Re: newbie question: for loop within for loop confusion
On Jun 15, 6:23 pm, takayuki [EMAIL PROTECTED] wrote:
def hasnolet(avoid):
fin = open('animals.txt')
for line in fin:
word = line.strip()
for letter in avoid:
if letter in word:
break
else:
print word
You're using the split command correctly, but you're not filtering
correctly. Consider this:
---begin---
fin = open('animals.txt')
\n.join([%s % line for line in fin if len(line.strip('abcd')) ==
len(line)])
end
Let's go slow.
\n.join([...])
1. Take everything that is in the following list, and print each one
with a carriage return appended to it.
\n.join([%s % line for line in fin ...])
2. For each line in fin, create a string that only consists of what
currently in the line variable, using string substitution.
\n.join([%s % line for line in fin if len(line.strip('abcd')) ==
len(line)])
3. Only do #2 if the length of the line after stripping out the
unnecessary characters is the same length as the line originally. This
way we filter out the lines we don't want. If we wanted the lines that
have been filtered, we can change == to != or =.
Now, I read Dive Into Python first, which through these early on in
the book. If your eyes cross looking at this, write it down and read
it again after you get a little farther into the book you're reading
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Re: newbie question: for loop within for loop confusion
On Jun 16, 2:34 pm, Thomas Hill [EMAIL PROTECTED] wrote:
On Jun 15, 6:23 pm, takayuki [EMAIL PROTECTED] wrote:
def hasnolet(avoid):
fin = open('animals.txt')
for line in fin:
word = line.strip()
for letter in avoid:
if letter in word:
break
else:
print word
You're using the split command correctly, but you're not filtering
correctly. Consider this:
---begin---
fin = open('animals.txt')
\n.join([%s % line for line in fin if len(line.strip('abcd')) ==
len(line)])
end
Let's go slow.
\n.join([...])
1. Take everything that is in the following list, and print each one
with a carriage return appended to it.
\n.join([%s % line for line in fin ...])
2. For each line in fin, create a string that only consists of what
currently in the line variable, using string substitution.
\n.join([%s % line for line in fin if len(line.strip('abcd')) ==
len(line)])
3. Only do #2 if the length of the line after stripping out the
unnecessary characters is the same length as the line originally. This
way we filter out the lines we don't want. If we wanted the lines that
have been filtered, we can change == to != or =.
Now, I read Dive Into Python first, which through these early on in
the book. If your eyes cross looking at this, write it down and read
it again after you get a little farther into the book you're reading
Guh, no, I'm reading the description of strip wrong. Fooey. Anyone
else able to one line it?
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Re: How to request data from a lazily-created tree structure ?
On Jun 16, 11:16 pm, Diez B. Roggisch [EMAIL PROTECTED] wrote: méchoui schrieb: Problem: - You have tree structure (XML-like) that you don't want to create 100% in memory, because it just takes too long (for instance, you need a http request to request the information from a slow distant site). - But you want to be able to request data from it, such has give me all nodes that are under a //foo/bar tree, and have a child with an baz attribute of value zzz. Question : Do you have any other idea to request data from a lazily-created tree structure ? And does it make sense to create a DOM-like structure and to use a generic XPath engine to request the tree ? (and does this generic XPath engine exist ?) The idea is to have the tree structure created on the fly (we are in python), only when the XPath engine requests the data. Hopefully the XPath engine will not request all the data from the tree (if the request is smart enough and does not contain **, for instance). Generic XPath works only with a DOM(like) structure. How else would you e.g. evaluate an expression like foo[last()]? So if you really need lazy evaluation, you will need to specifically analyze the query of interest and see if it can be coded in a way that allows to forget as much of the tree as possible, or even better not query it. Diez Yes, I need to make sure my requests are properly written so that the generic XPath engine does not need all the structure in memory. There are quite a few cases where you really don't need to load everything at all. /a/b/*/c/d is an example. But even with an example like /x/z[last()]/t, you don't need to load everything under the every /x/z nodes. You just need to check for the latest one, and make sure there is a t node under it. Anyway, if I need to make requests that need all the data... that means that the need for lazy instantiation of nodes disappears, right ? -- http://mail.python.org/mailman/listinfo/python-list
Please explain Python __whatever__ construct.
After a couple of weeks studying Python, I already have a few useful scripts, including one that downloads 1500 Yahoo stock quotes in 6 seconds. However, many things are puzzling to me. I keep on seeing things like __main__ in scripts. A more obscure example would be __add__ used in string concatenation. For example, I can use Hello +world (or just Hello world) to join those two words. But I can also use Hello .__add__(world). When and why would I ever use __main__ or the many other __whatever__ constructs? -- http://mail.python.org/mailman/listinfo/python-list
Re: Simple and safe evaluator
George Sakkis wrote:
On Jun 16, 4:47 pm, bvdp [EMAIL PROTECTED] wrote:
2. I thought I'd be happy with * / + -, etc. Of course now I want to add
a few more funcs like int() and sin(). How would I do that?
For the builtin eval, just populate the globals dict with the names
you want to make available:
import math
globs = {'__builtins__' : None}
# expose selected builtins
for name in 'True False int float round abs divmod'.split():
globs[name] = eval(name)
# expose selected math constants and functions
for name in 'e pi sqrt exp log ceil floor sin cos tan'.split():
globs[name] = getattr(math,name)
return eval(s, globs, {})
Thanks. That was easy :)
The change to the _ast version is left as an exercise to the reader ;)
And I have absolutely no idea on how to do this. I can't even find the
_ast import file on my system. I'm assuming that the _ast definitions
are buried in the C part of python, but that is just a silly guess.
Bob.
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