ANN: CherryPy 3.0.0 beta 2
On behalf of the CherryPy team I'd like to announce the availability of CherryPy 3.0.0 beta 2. There have been some significant bug fixes and improvements since the first beta release a few weeks ago. Here are some highlights: * All CherryPy exceptions now inherit from CherryPyException * The permission bug with the error log has been corrected. * Builtin SSL support! (requires PyOpenSSL). * New cherrypy.url() function replaces tree.url and request.url. * New builtin tools for basic and digest authentication. * Encoding bug fixes.For more details on 3.0, see the following URLs: * http://www.cherrypy.org/wiki/WhatsNewIn30 * http://www.cherrypy.org/wiki/UpgradeTo30 Thanks to the CherryPy community for all of the bug reports and comments on the first beta. Please try out this latest release and let us know what you think. Christian WyglendowskiCherryPy Team -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html
Re: does anybody earn a living programming in python?
Steven D'Aprano [EMAIL PROTECTED] Wrote: On Tue, 26 Sep 2006 22:00:55 +1000, Anthony Baxter wrote: This seems to be a very, very silly original post. I know of plenty of people who make a living programming Python. It's been the vast majority of the programming (for money) I've done in the last ten years, and there's countless other people I know here in Melbourne in the same position. Countless people? Are we talking aleph-zero people (countable infinity) or one of the uncountable infinities? -- Steven. Oh dont be so pedantic - countless - without count - probably just means that nobody has bothered to count them... - Hendrik -- http://mail.python.org/mailman/listinfo/python-list
RE: Starting Win32 Service
[placid] | Now i was trying to use service.ChangeStartMode but each | time i pass in | an argument i get the error; | | #TypeError: __call__() takes exactly 1 argument (2 given) | | but; | | print service.ChangeStartMode | function ChangeStartMode (StartMode) = (ReturnValue) | | ChangeStartMode needs an argument! | | What im i doing wrong here? | | And to answer my own question, the way to pass in arguments is via the | key=value way so; | | service.ChangeStartMode(StartMode = Automatic) Yes, sorry about that, it's a well-known (to me) gotcha. Basically there's no way I can extract the params from the COM interface in a way which implies order, so I can't take them in positionally. (Corrections to this statement will be gratefully received). TJG This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk -- http://mail.python.org/mailman/listinfo/python-list
Re: ctypes pointer to pointer
At Wednesday 27/9/2006 22:58, Podi wrote:
I have a C function in the dll does the following:
DLL_API int dll_foo(char **data, size_t *size)
{
strcpy(*data, hello);
*size = strlen(*data);
return 0;
}
So I would call the function as such,
char data[8];
size_t size;
int status = dll_foo(data, size);
I have tried the following in Python but not able to get it working...
Any help would be appreciated!
from ctypes import *
mydll = windll.mydll
array = c_char * 8
data = array()
size = c_long()
status = mydll.dll_foo(byref(data), byref(size))
Traceback (most recent call last):
File interactive input, line 1, in ?
WindowsError: exception: access violation writing 0x
I'd use your last try. But since it didnt work, use a prototype and
see what happens:
data = create_string_buffer('\000' * 8)
size = c_long()
dll_foo = mydll.dll_foo
dll_foo.argtypes = [POINTER(c_char_p), POINTER(c_long)]
status = dll_foo(byref(data), byref(size))
Are you sure your function is compiled using the stdcall calling
convention? I'm not sure what means DLL_API.
Gabriel Genellina
Softlab SRL
__
Preguntá. Respondé. Descubrí.
Todo lo que querías saber, y lo que ni imaginabas,
está en Yahoo! Respuestas (Beta).
¡Probalo ya!
http://www.yahoo.com.ar/respuestas
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Re: Top and Bottom Values [PEP: 326]
On 2006-09-27, George Sakkis [EMAIL PROTECTED] wrote: Antoon Pardon wrote: What bothers me a bit about the rejection of PEP 326 is that one of the reasons stated is: http://mail.python.org/pipermail/python-dev/2004-January/042306.html - it is easily implemented when you really need it Well I thought it would simplify some things for me, so I tried an implementation and then found that some of the things that I would want to do with it wont work. So the is easily implemented bit seems not to be correct. IIRC, the PEP proposed the Smallest and Largest singletons with the sole purpose of being used in comparisons. No numeric behavior was implied, i.e. Smallest and Largest are not negative and positive infinity in the math sense of the word. That is true. So I guess the easily implemented refers to this case alone. This doesn't follow. Take the example were I got stuck. lst = range(10) lst[:Top] This doesn't need arithmetics done with Top. The only fact that you need is: Top = len(lst). In a way this isn't that difficult in itself, it becomes difficult because python doesn't allow ducktyping for a lot of its builtins. I could write my own function: def leftslice(lst, num): return [ tp[1] for tp in enumerate(lst) if tp[0] num ] This function works as expected if you substituted Top for num and as you can see, no arithmetic is done on num, only comparisons. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Difference between two dates in seconds
Fredrik Lundh schreef: snip def get_seconds(td): ... return td.days * (24*60*60) + td.seconds ... import dis dis.dis(get_seconds) 2 0 LOAD_FAST0 (td) 3 LOAD_ATTR0 (days) 6 LOAD_CONST 4 (86400) 9 BINARY_MULTIPLY 10 LOAD_FAST0 (td) 13 LOAD_ATTR1 (seconds) 16 BINARY_ADD 17 RETURN_VALUE /F Ha, i didn't know about the dis module. Looks fun. I get these results: def get_seconds(td): ... return td.days * (24*60*60) + td.seconds ... dis.dis(get_seconds) 2 0 LOAD_FAST0 (td) 3 LOAD_ATTR1 (days) 6 LOAD_CONST 1 (24) 9 LOAD_CONST 2 (60) 12 BINARY_MULTIPLY 13 LOAD_CONST 2 (60) 16 BINARY_MULTIPLY 17 BINARY_MULTIPLY 18 LOAD_FAST0 (td) 21 LOAD_ATTR2 (seconds) 24 BINARY_ADD 25 RETURN_VALUE def get_seconds2(td): ... return td.days * 86400 + td.seconds dis.dis(get_seconds2) 2 0 LOAD_FAST0 (td) 3 LOAD_ATTR1 (days) 6 LOAD_CONST 1 (86400) 9 BINARY_MULTIPLY 10 LOAD_FAST0 (td) 13 LOAD_ATTR2 (seconds) 16 BINARY_ADD 17 RETURN_VALUE Using 86400 instead of (24*60*60) is faster Benedict -- http://mail.python.org/mailman/listinfo/python-list
Re: a different question: can you earn a living with *just* python?
John J. Lee wrote: ISTM that there's a vast amount of mostly-tacit knowledge about the way things work, and they way they should work, good practices, design techniques, rules of thumb, Bad Ideas ;-), etc. etc. that good programmers do have and bad or inexperienced programmers don't. Yep, I think that's the point. Worth repeating (and +1 for QOTW). Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Can string formatting be used to convert an integer to its binary form ?
Hi, String formatting can be used to converting an integer to its octal or hexadecimal form: a = 199 %o % a '307' %x % a 'c7' But, can string formatting be used to convert an integer to its binary form ? Thanks in advance. xiaojf -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
On 2006-09-27, OKB (not okblacke) [EMAIL PROTECTED] wrote: Antoon Pardon wrote: To begin with this already fails: for i in xrange(Top): ... print i What do you expect this to do? Loop forever? Yes that is what I would expect. If someone would ask me to implement a function like xrange it would look something like the following (*) def xrange(start=1, stop, step=1): while start stop: yield start start += step Since Top is supposed to be bigger than any other value this would indeed loop forever. The only reason that this doesn't work with the builtin, is because the builtin xrange insist on its arguments being ints instead of allowing duck typing. (*) Yes I know this isn't legal python. I just wrote it like this to make the intention clear instead of putting in the code that would actually behave like xrange with regards to its defaults. IMO that would just detract from the actual code. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: a query on sorting
Paul McGuire wrote: Steve Holden [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] snip [x for x in enumerate(a)] [(0, 9), (1, 4), (2, 3), (3, 5), (4, 2), (5, 6), (6, 7), (7, 1), (8, 2)] Just curious, Steve, but why do this list comprehension when: list(enumerate(a)) works just as well? Dumb stupidity would account for that. Knowing that enumerate(a) was an iterator I simply used the first iterative context that came to mind. List is somewhat more effective. In the interests of beating a dead horse into the ground (metaphor-mixing?), I looked at using map to one-line the OP's request, and found an interesting inconsistency. I tried using map(reversed, list(enumerate(a))), but got back a list of iterators. To create the list of tuples, I have to call the tuple constructor on each one, as in: map(tuple,map(reversed,list(enumerate(a However, sorted returns a list, not a listsortediterator. Why the difference in these two builtins? Ask the developers. Beats me ... I guess you can beat a dead horse into the ground, but you can't make him drink. I guess. Thanks for flogging this horse so effectively. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: a different question: can you earn a living with *just* python?
Ben Finney wrote: I submit that a programmer who knows *only* one programming language can never be an expert in that language; it is only exposure to multiple tools and ways of programming that can grow a one-trick pony into an expert. Well, it all depends on the definition of expert. Python is written in C, so if by expert of Python you mean somebody who knows its internal working, its is clear that that person must know C. However, even knowing Python only gives you a lot of multiple tools and ways of programming, much more than knowing Java or Visual Basic. That was my point. Also, I believe that a person who knows Python has no reason to learn Java or Visual Basic (except for pragmatic purposes). After Python I learned Scheme and if I had time I would give a look at Haskell, or some other different language. BTW I decided not to learn Ruby it is not really different from Python in terms of learning new ways of programming. Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: a different question: can you earn a living with *just* python?
Roy Smith wrote: The problem is, if the complex features are there, people will use them. On any large project, there will always be some people who revel in using every obscure feature of a language. That forces everybody else on the team (and all future members of the team) to know (or learn) those features in order to be able to use and maintain the code base. Well, I am sympathetic with your point and I actually would have no problem if metaclasses and multiple inheritance were removed from the language. However my point was a different one. If you know all this stuff, you are likely to be able to learn any language. My point was that when hiring a programmer, one should also look at the potential of the person, not only at his/her present skills. Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: Can string formatting be used to convert an integer to its binary form ?
[EMAIL PROTECTED] schreef: Hi, String formatting can be used to converting an integer to its octal or hexadecimal form: a = 199 %o % a '307' %x % a 'c7' But, can string formatting be used to convert an integer to its binary form ? Thanks in advance. xiaojf I don't actually know how to do it with string formatting but you can create a simple function to do it. Here's an example: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/219300 Regards, Benedict -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
On 2006-09-27, Tim Chase [EMAIL PROTECTED] wrote: To begin with this already fails: for i in xrange(Top): ... print i What do you expect this to do? Loop forever? Perhaps the infinite loop should take half as long as for i in xrange(Bottom, Top): print i Though then the values when the loop first starts are kinda ambiguous... :) Given the limits of xrange: for i in xrange(10,19): ... print i Traceback (most recent call last): File stdin, line 1, in ? OverflowError: long int too large to convert to int I suspect one would have an overflow condition to help break you out of the loop... Sometime people want an infinite loop. Personnaly I don't see why I should get an overflow error while doing this: import sys for i in xrange(sys.maxint - 4, sys.maxint + 5): pass I remember in the days when longs and ints were being unified, that some people complained, because without this unification, a loop in which an int counter was incremented would necessarily end when the counter overflowed and this was a good indication there was a bug somewhere. The response to that was, that you could never foresee how your algorithm would be used and that maybe someday someone found a good way to use your algoritm where the counter would go beyond sys.maxint. Following this logic there is no reason why xrange should be limited to ints. try: ... for i in range(Top): ... print i ... except OverflowError: ... print 'done!' ...and then you time your instruction cycles and your disk reads so they fall under the read-head at just the right time... [*] [*] http://www.catb.org/jargon/html/story-of-mel.html There is no reason to compare what I propose to the story of melvin. All behaviour of the objects would be well defined and could be easily understood to those who would read the documentation. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: QuoteSQL
Lawrence D'Oliveiro [EMAIL PROTECTED] wrote: In message [EMAIL PROTECTED], Duncan Booth wrote: Deary me. Did you actually test out that bit of code before you posted it? execfile(QuoteSQL.py) EscapeSQLWild(r\%) '%' SQLString(% + EscapeSQLWild(r\%) + %) '%%%' EscapeSQLWild(r\%) == r\\% True SQLString(% + EscapeSQLWild(r\%) + %) == r'%%%' True Ah, so that's a 'no' then. I can't see any tests there. How do you know that those strings work correctly MySQL queries? Please, open your mind to what I'm saying. I'm not trying to criticise your aims, just trying to point out the simple fact that your EscapeSQLWild function has a bug. If nothing else, the fact that you are finding this so hard to understand shows that there is a need for a correctly written function to do this. The fix to EscapeSQLWild to get test_escapebackslashwild2 to work is a trivial change, and not suprisingly also makes the other failing test in my script (the one using parameterised queries and EscapeSQLWild) pass. Again, please, try running the script I posted, and in particular test_escapebackslashwild2. It uses the SQL query you yourself created, and it fails because it matches something it shouldn't. -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
On 2006-09-27, Steven D'Aprano [EMAIL PROTECTED] wrote: On Wed, 27 Sep 2006 13:37:40 +, Paul McGuire wrote: Here's a little more refined version of my previous post: class StubbornInt(int): def invariantOp(self,other): return self __add__ = invariantOp __sub__ = invariantOp [snip rest of code] import sys Top = StubbornInt(sys.maxint) Top shouldn't need to depend on a specific integer value, but then it is easy enough to subclass StubbornInt. However, there is a more serious problem with your definition of Top: Top sys.maxint+1 False But Top is supposed to bigger than everything, right? Okay, let's fix it: class FixedTop(StubbornInt): def __init__(self): super(FixedTop, self).__init__(sys.maxint) self.name = 'Top' def _bigger(self, other): # Top is bigger than everything return True def _smaller(self, other): # Top is smaller than nothing return False __lt__ = __le__ = _smaller __gt__ = __ge__ = _bigger Let's test it out: Top = FixedTop() Top 45 True Top sys.maxint True Top 2L**512 True Top None True Top hello True So far so good. However, the downside of rolling your own Top is the risk that one day you'll have something like this: class Funny: def __init__(self, name): self.name = name def __str__(self): return self.name def __gt__(self, other): return len(str(self)) len(str(other)) and then you'll have problems: bottom = Funny(Bottom) Top bottom True bottom Top True As far as I can see, the only way to avoid edge cases like this is for Top (and Bottom) to be built-ins that are special-cased by Python. An other problem is that if you roll your own, they wont be accepted in a lot of buitins where they would make sense. Take itertools.repeat as it is now and I understand correctly there are two possibilities. 1) Your extreme values are not a subclass of int, then you won't be able to use them as a times arguments. 2) Your extreme values are a subclass of int, then they will somehow have an int value and this int value will be used, so that the repeat won't be an infinite loop. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: A critique of cgi.escape
Lawrence D'Oliveiro [EMAIL PROTECTED] wrote: Also, because Python has a conservative policy on backwards incompatible changes, you are protected from some wanker going and changing the HTML safe mappings arbitrarily, say using numerical entity references instead of gt;, lt; and amp;. Why would that be wrong? It would still be consistent with the documentation. It would be wrong as he said because Python has a conservative policy on backwards incompatible changes. In general (although they may not always succeed) Python's core developers try not to change functionality even when that functionality isn't clearly documented. Rather if it becomes an issue they would prefer to clarify the documentation. Yes, there is a downside to this: a lot of the Python standard libraries aren't as good as they could be if incompatible changes were allowed, but it does reduce maintenance headaches. The solution is usually that when the standard api is insufficient you wrap it in something else. cgi.escape is a good example: most people writing web applications never call it directly because they produce their html output using a templating language which does all the necessary quoting for them automatically (e.g. Zope's tal language). If you use tal then you have zero chance of forgetting to use quote; in a situation where it is required, but an incompatible change to cgi.escape could still break your existing code. -- http://mail.python.org/mailman/listinfo/python-list
Re: XSLT speed comparisons
Sorted!
I installed msxml4 and then struggled for an hour or so with an
encoding error (UnicodeEncodeError: 'ascii' codec etc) which was
fixed by altering your code from:
return proc.output -- return proc.output.encode('utf-8')
The performance of MSXML over 4suite is substantial.
4suite: http://python.pointy.co.nz/test = 2.5s
MSXML: http://python.pointy.co.nz/test_msxml = 1.1s
I'd like to eventually break all ties with MS at some stage. It'll be
interesting to test this performance on a Linux server.
Thank you for your help.
Damian
--
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Re: Difference between two dates in seconds
flupke [EMAIL PROTECTED] wrote: Using 86400 instead of (24*60*60) is faster s/is/was/ upgrade to Python 2.5 -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
efrat wrote:
Hello,
I'm planning to use Python in order to teach a DSA (data structures
and algorithms) course in an academic institute. If you could help out
with the following questions, I'd sure appreciate it:
(snip)
2. Suppose I have some file example.py, and I'd like to incorporate it
**into** part of an HTML page with nice syntax highlighting and all the
shebang. Is there an easy way to do so?
I suppose this has more to do with the course presentation than with
it's content !-)
However, Trac's wiki is probably a good solution here.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: Difference between two dates in seconds
Duncan Booth schreef: flupke [EMAIL PROTECTED] wrote: Using 86400 instead of (24*60*60) is faster s/is/was/ upgrade to Python 2.5 Indeed, i'm still on 2.4. I thought 2.5 might give a different result :) Thanks for the info Benedict -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
Antoon Pardon wrote: On 2006-09-27, George Sakkis [EMAIL PROTECTED] wrote: Antoon Pardon wrote: What bothers me a bit about the rejection of PEP 326 is that one of the reasons stated is: http://mail.python.org/pipermail/python-dev/2004-January/042306.html - it is easily implemented when you really need it Well I thought it would simplify some things for me, so I tried an implementation and then found that some of the things that I would want to do with it wont work. So the is easily implemented bit seems not to be correct. IIRC, the PEP proposed the Smallest and Largest singletons with the sole purpose of being used in comparisons. No numeric behavior was implied, i.e. Smallest and Largest are not negative and positive infinity in the math sense of the word. That is true. So I guess the easily implemented refers to this case alone. This doesn't follow. Take the example were I got stuck. lst = range(10) lst[:Top] FWIW, this works with 2.5 and the __index__ slot: class Top(object): ... def __index__(self): ... return sys.maxint ... a=range(5) a[:Top()] [0, 1, 2, 3, 4] Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: Can string formatting be used to convert an integer to its binary form ?
Thus spoke [EMAIL PROTECTED] (on 2006-09-28 09:10):
String formatting can be used to converting an integer to its octal or
hexadecimal form:
a = 199
%o % a
'307'
%x % a
'c7'
But, can string formatting be used to convert an integer to its binary
form ?
I didn't fell over this problem so far but
I *would* have expected to find something
like a 'pack' operator (as in Perl).
And voilá, there is (even basically identical to Perl):
from struct import *
a = 199
a_bin_str = pack('L', a)
Regards
Mirco
--
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Re: Top and Bottom Values [PEP: 326]
Antoon Pardon wrote: On 2006-09-27, OKB (not okblacke) [EMAIL PROTECTED] wrote: Antoon Pardon wrote: To begin with this already fails: for i in xrange(Top): ... print i What do you expect this to do? Loop forever? Yes that is what I would expect. For unterminating loops, use while 1:, and if you need the counter, itertools.count(). If someone would ask me to implement a function like xrange it would look something like the following (*) def xrange(start=1, stop, step=1): while start stop: yield start start += step Since Top is supposed to be bigger than any other value this would indeed loop forever. The only reason that this doesn't work with the builtin, is because the builtin xrange insist on its arguments being ints instead of allowing duck typing. xrange() *could* be implemented as shown above, but do you realize that it would be a severe performance hit compared to the current implementation, which doesn't give almost all users a benefit at all? Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: windev vs python SOS
stéphane bard wrote:
hello, my boss ask me to prefer windev to python.
Find another job.
(I'm serious. I've 2+ years of pain with Windev, and if your boss is
clueless enough to believe all the marketing crap from PCSoft's droids,
you really don't want to work for him).
I have to argue
- python work on multiple platform (linux, mac, windows)
A good point but it didn't interest him. Because
we want to choose a language for prototyping.
Python is far better at this than Windev - and the prototype is
usually quite usable.
So multi platform is not enough.
- python and windev are fast to develop
Nope. Windev lets you quickly have a barely usable DB-GUI pipeline, and
then trouble begins. Python, OTHO, really lets you do the job.
- windev as a good IDE, python? boa-constructor is ok with wxpython
Aren't you confusing IDE with RAD ?
- python is open source (that's not an argument for my boss, sorry
it's a boss ...)
Python is free. And being a boss doesn't necessarily imply being stupid.
any idea for a strong argument ?
My own argument would be it's Python or it's without me g
More seriously: since you're in a Window-only shop, portability may not
be a strong argument. But Python is also very good at Windows-specific
stuff (COM etc) - and is widely used by Windows programmers (at least in
France). FWIW, you may want to post this on fclpy too - there are some
hard-core Windows developpers there...
You can also point your boss to IronPython - if MS puts some money on
it, it can't be a bad tool, isn't it ?-)
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: windev vs python SOS
John Henry wrote:
I don't know what windev is
A french (highly proprietary) so-called CASE-Tool with a so-called
5th generation language (lol) that is mostly a dumbed-down mix of
basic and pascal. It's so bad that it makes you regret VB6.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: does anybody earn a living programming in python?
Stuart Bishop wrote: My personal experience is that there is a shortage of good Python programmers. In Melbourne, Australia for example there is a continual need for about 2 more - one Python shop there just hires clueful developers and makes their first task 'learn Python'. We generally have a few positions open at any particular moment too - http://www.ubuntu.com/employment (but we are picky - it is hard to hand hold when the hand is several time zones away). It's much easier to learn Python than it is to learn good general software development skills, so I think that's a good approach. My room mate here at work didn't know any Python programming before he came, but he was fluent pretty soon. Like me, he's starting to make stupid mistakes in C++, such as forgetting trailing ; after each line. :) We are fairly picky here when we employ people, but while we appreciate that they already know Python, we don't see it as a major issue. It's quick and easy to learn. Mentioning Python in job ads is maybe more a way to attract people who take clever initiatives. On a slight tangent, one of the appealing things about Python (and other 'non-mainstream' languages) in the past has been that the people who knew Python also tended to be the people you wanted to employ - they generally had experience in other languages but moved onto something they perceived as 'better' either at work or home. It indicated a level of care and pride about their profession rather than someone who just treated cutting code as a day job. That depends if you are an employer who wants to lead a team of skilled professionals or if you prefer a herd of sheep that you lead around with a stick. So, as someone who want to be employed, you influence what kinds of job you tend to get with what you learn. Do you prefer a job where you are just expected to do exactly what you are told, or are you eager to take initiatives and change your work place to something better? -- http://mail.python.org/mailman/listinfo/python-list
Re: Can string formatting be used to convert an integer to its binary form ?
At Thursday 28/9/2006 05:22, Mirco Wahab wrote:
String formatting can be used to converting an integer to its octal or
hexadecimal form:
a = 199
%o % a
'307'
%x % a
'c7'
But, can string formatting be used to convert an integer to its binary
form ?
a = 199
a_bin_str = pack('L', a)
Notice that the OP was looking for another thing, given the examples.
Perhaps a better wording would have been how to convert an integer
to its base-2 string representation.
Gabriel Genellina
Softlab SRL
__
Preguntá. Respondé. Descubrí.
Todo lo que querías saber, y lo que ni imaginabas,
está en Yahoo! Respuestas (Beta).
¡Probalo ya!
http://www.yahoo.com.ar/respuestas
--
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Re: Top and Bottom Values [PEP: 326]
On 2006-09-28, Georg Brandl [EMAIL PROTECTED] wrote: Antoon Pardon wrote: On 2006-09-27, OKB (not okblacke) [EMAIL PROTECTED] wrote: Antoon Pardon wrote: To begin with this already fails: for i in xrange(Top): ... print i What do you expect this to do? Loop forever? Yes that is what I would expect. For unterminating loops, use while 1:, and if you need the counter, itertools.count(). Neither of these will work if you want an easy way to choose between repeating a specific number of times and an infinite loop. Of course you can include special tests in your code, but the purpose of values like Top is to eliminate special case code in a number of situations. If someone would ask me to implement a function like xrange it would look something like the following (*) def xrange(start=1, stop, step=1): while start stop: yield start start += step Since Top is supposed to be bigger than any other value this would indeed loop forever. The only reason that this doesn't work with the builtin, is because the builtin xrange insist on its arguments being ints instead of allowing duck typing. xrange() *could* be implemented as shown above, but do you realize that it would be a severe performance hit compared to the current implementation, which doesn't give almost all users a benefit at all? That code was just meant to illustrate behaviour, one could always code as follows: def _xrange(start=1, stop, step=1): # see implemantation above def xrange(start=1, stop, step=1): if (type(start), type(stop), type(step)) == (int, int, int): return builtin.xrange(start, stop, step) else: return _xrange(start, stop, step) Just to show that with some thinking one could come up with an implementation that was fast in most cases and yet would allow for other types than ints if that would make sense. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: PostgreSQL, psycopg2 and OID-less tables
Stuart Bishop wrote: [...] If you are using a modern PostgreSQL (8.1 for sure, maybe 8.0), this is better spelt: cur.execute(SELECT currval(pg_get_serial_sequence(%s, %s)) % ( tableid, columnid)) (Assuming of course your table name and column name don't contain odd characters like = or ' or ., in which case you need to properly quote them). The reason it is better is that in odd cases the sequence name will not always be %(tableid)s_%(columnid)s_seq, such as after you have renamed a table. Thank you! I've been looking for this for about six months - it helps to provide portability, and my current techniques relied on standard naming of the sequences. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: License / Registration key enabled software
Ben Finney wrote: Mike Playle [EMAIL PROTECTED] writes: License keys exist to make it easier for honest users to remain honest. What doubletalk. If usage restrictions were in *any* way what end users wanted, they'd choose software that has it over software that does not. Usage restrictions serve *no* want of the end user. No, but usage reporting is very important to large organisations with enterprise copies of their applications. They want to stay in compliance, and it's notoriously hard to track usage. For instance a customer might want to buy a license to use your software on up to 5 machines at once, but still have the software installed on every machine in the company. This need is adequately served by not imposing usage restrictions. Any effective imposition of usage restrictions is hostile to the wants of the user. If usage restrictions are brought into the picture, it is to serve the wants of someone else, *not* the end user. It is disingenuous to suggest otherwise. So you're suggesting that most people would rather be dishonest? Otherwise you might as well say that any costs associated with using a piece of software (including purchase pricing) are hostile to the wants of the user. License systems like FlexLM can work here, to make it easier for them to ensure that they comply with the terms of the license. This is describing a want of the copyright holder, *not* the end user. I think your view is a little biased here. Forget about the people who'll crack your software. Ask yourself whether a license key scheme offers anything to the people who won't try to crack it. If it does, then actually implementing the scheme becomes trivial; if it doesn't, then leave it out, because it won't help against crackers. Very sound advice, I agree entirely. As do I. The sad thing is that the people most concerned about protection of intellectual property are often the ones whose IP is least likely to need protection. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
efrat wrote: 1. What exactly is a Python list? If one writes a[n], then is the complexity Theta(n)? If this is O(1), then why was the name list chosen? If this is indeed Theta(n), then what alternative should be used? (array does not seem suited for teaching purposes.) A Python list is an array of object references that has some empty slots (or one empty slot?) for growing quickly to the right. If you want to make a chained structure, then perhaps you know LISP? This is what the basic machinery of LISP looks like in Python: def cons(a,b) return [a,b] def car(structure) return structure[0] def cdr(structure) return structure[1] Python lists are more powerful than you would think! You don't need classes or OOP to create linked lists or tree structures in Python. Remember that O(1) is not neccesarily faster than O(N)! Unless your linked list is very big, you will get something called a 'cache miss' inside your CPU. Thus it is usually more efficient to work with dynamic arrays. Further, you can create hybrid array-list structures (e.g. Java's ArrayList) that outperform lists and arrays with respect to adding new elements. But they will have to be tuned to your particular hardware architecture. Growing a linked list node by node is an excercise for fools (and DSA students?) It may look good in DSA textbooks, but it is extremely inefficient on real world computers. Python's lists are implemented as dynamic arrays internally to be efficient on the kind of data we normally work with. Not only do small dynamic arrays grow faster than small lists, they also index much faster. Why are they called lists then? Because Guido want you to look at them conceptually as lists. That is what they are. If you want real 'fixed size' arrays like Fortran and Matlab, then you should add 'NumPy' to your Python (http://www.scipy.org). Your science and engineering students will find NumPy, SciPy and Matplotlib (http://matplotlib.sourceforge.net) valuable, so direct them to those sources. -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
On 2006-09-28, Georg Brandl [EMAIL PROTECTED] wrote: Antoon Pardon wrote: On 2006-09-27, George Sakkis [EMAIL PROTECTED] wrote: Antoon Pardon wrote: What bothers me a bit about the rejection of PEP 326 is that one of the reasons stated is: http://mail.python.org/pipermail/python-dev/2004-January/042306.html - it is easily implemented when you really need it Well I thought it would simplify some things for me, so I tried an implementation and then found that some of the things that I would want to do with it wont work. So the is easily implemented bit seems not to be correct. IIRC, the PEP proposed the Smallest and Largest singletons with the sole purpose of being used in comparisons. No numeric behavior was implied, i.e. Smallest and Largest are not negative and positive infinity in the math sense of the word. That is true. So I guess the easily implemented refers to this case alone. This doesn't follow. Take the example were I got stuck. lst = range(10) lst[:Top] FWIW, this works with 2.5 and the __index__ slot: class Top(object): ... def __index__(self): ... return sys.maxint ... a=range(5) a[:Top()] [0, 1, 2, 3, 4] It is something worth investigating, but I'm not sure it will suite my purpose. You see I have a table module, a table is like a list except the base index doesn't need to be 0. So I could have a table that is indexable from sys.maxint - 3 to sys.maxint + 7. I'm not sure tbl[:Top] would do what it is supposed to do in those circumstances. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Auto color selection PIL
Gabriel Genellina wrote: Try this. It first chooses 0, 1/2, then 1/4, 3/4, then */8... It's the best I could make if you don't know the number of colors beforehand. If you *do* know how many colors, your previous response is OK. Um, that's the same thing my second suggestion does: h = hues() h.next() 0.0 h.next() 0.5 h.next() 0.25 h.next() 0.75 h.next() 0.125 Your implementation is less terse than mine, though. And I suspect it runs faster, though I haven't checked that. -- http://mail.python.org/mailman/listinfo/python-list
Writing 2d array in an ascci file
Hi, I want to write an 2d array in an ascii file using numpy. There's the - tofile / fromfile - function but it doesn't work with nd array. Thanks, CH. -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
Antoon Pardon [EMAIL PROTECTED] writes: It is something worth investigating, but I'm not sure it will suite my purpose. You see I have a table module, a table is like a list except the base index doesn't need to be 0. So I could have a table that is indexable from sys.maxint - 3 to sys.maxint + 7. I'm not sure tbl[:Top] would do what it is supposed to do in those circumstances. Top = object() class Table(list): def __getitem__(self, n): get = super(Table, self).__getitem__ if n is Top: return get(-1) return get(n - self.baseindex) a=Table(range(9)) a.baseindex = 3 print a[5], a[Top] 2 8 -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
Some of your Lisp translations are subtly off... Date: 28 Sep 2006 02:49:50 -0700 From: sturlamolden [EMAIL PROTECTED] Subject: Re: Questions on Using Python to Teach Data Structures and Algorithms To: python-list@python.org If you want to make a chained structure, then perhaps you know LISP? This is what the basic machinery of LISP looks like in Python: def cons(a,b) return [a,b] should be: return [a].extend(b) def car(structure) return structure[0] def cdr(structure) return structure[1] should be: return structure[1:] B. -- Brendon Towle, Ph.D. [EMAIL PROTECTED] +1-412-362-1530 “Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.” – Brian W. Kernighan -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
Paul Rubin http://[EMAIL PROTECTED] writes: sys.maxint - 3 to sys.maxint + 7. I'm not sure tbl[:Top] would do what it is supposed to do in those circumstances. Top = object() class Table(list): ... Oh wait, I missed the : in your tbl[:Top] example. Yeah, you could hair up Table to account for slices, I'll leave the exercise to you. -- http://mail.python.org/mailman/listinfo/python-list
Re: Can string formatting be used to convert an integer to its binary form ?
Thus spoke Gabriel Genellina (on 2006-09-28 11:05):
At Thursday 28/9/2006 05:22, Mirco Wahab wrote:
But, can string formatting be used to convert an integer to its binary
form ?
a = 199
a_bin_str = pack('L', a)
Notice that the OP was looking for another thing, given the examples.
Perhaps a better wording would have been how to convert an integer
to its base-2 string representation.
Yes, you are right. The OP looks for a
'binary (bit) representation ...
I admit I didn't find out how to format
a value into a bit string in Python.
In Perl, this would be a no-brainer:
$var = 199;
$str = sprintf %0*b, 32, $var;
and str would contain 11000111
on a intel machine.
But where is the %b in Python?
Regards Thanks
Mirco
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Re: Writing 2d array in an ascci file
[EMAIL PROTECTED] wrote:
I want to write an 2d array in an ascii file using numpy. There's the -
tofile / fromfile - function but it doesn't work with nd array.
Is this good enough?
x = numpy.zeros( (10, 10) )
f = open('out.txt', 'w')
print f, str(x).replace('[',' ').replace(']', ' ')
f.close()
Jeremy
--
Jeremy Sanders
http://www.jeremysanders.net/
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Re: Computer Language Popularity Trend
Xah Lee wrote: Computer Language Popularity Trend This page gives a visual report of computer languages's popularity, as indicated by their traffic level in newsgroups. This is not a comprehensive or fair survey, but does give some indications of popularity trends. http://xahlee.org/lang_traf/index.html Xah [EMAIL PROTECTED] ∑ http://xahlee.org/ And not a single deletable expletive in sight. Good stuff! regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
Brendon Towle wrote:
Some of your Lisp translations are subtly off...
Seems correct to me. Lisp lists are linked lists, not arrays.
Date: 28 Sep 2006 02:49:50 -0700
From: sturlamolden [EMAIL PROTECTED]
Subject: Re: Questions on Using Python to Teach Data Structures and
Algorithms
To: python-list@python.org
If you want to make a chained structure, then perhaps you know LISP?
This is what the basic machinery of LISP looks like in Python:
def cons(a,b)
return [a,b]
should be:
return [a].extend(b)
A Lisp cons is made of a reference to it's content and a reference to
the rest of the list, so cons = lambda a, b : [a, b] seems the most
straightforward translation.
def car(structure)
return structure[0]
def cdr(structure)
return structure[1]
should be:
return structure[1:]
idem.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Python and Win95B
I've just installed Python 2.5 under Win95B, and when run it says The PYTHON25.DLL file is linked to missing export KERNEL32.DLL.GetFileAttributesExA. Does Python 2.5 not run under Win95? If not, is there an earlier version of Python which does? Thanks, Ciarán Ó Duibhín. -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
efrat wrote: I'm planning to use Python in order to teach a DSA (data structures and algorithms) course in an academic institute. If you could help out with the following questions, I'd sure appreciate it: 1. What exactly is a Python list? It's almost exactly what the doc says (and exactly what the code implements). If one writes a[n], then is the complexity Theta(n)? No; as others have pointed out, it's O(1). If this is O(1), then why was the name list chosen? Because it *is* a list: an ordered collection in which an element might appear multiple times. It's also an extensible array, but that's so more verbose. If this is indeed Theta(n), then what alternative should be used? (array does not seem suited for teaching purposes.) It's not Theta(n), and the array classes are fine for teaching. 2. Suppose I have some file example.py, and I'd like to incorporate it **into** part of an HTML page with nice syntax highlighting and all the shebang. Is there an easy way to do so? Yes. In fact its probably easier, or at least no harder, than making sense of what you mean there. (Sorry, but any Google query involving Python and HTML (with any other additional terms) led to Python HTML processing libraries.) Don't be sorry about about getting the info you need (whether or not you realize it is the info you need). 3. Are there any useful links for Python/DSA education? Yes, many. Python is fine for teaching data structures and algorithms. Python's loosely-defined duck typing makes it pedagogically inappropriate for some topics, but as far as you have described your course, Python should work well. I found Data Structures and Algorithms with Object Oriented Design Patterns (http://www.brpreiss.com/books/opus7/html/book.html). It is a fine book, but it is unsuitable: my students are electrical-engineers, and barely know how to program; teaching them DSA, python, **and** stuff like the visitor pattern seems impossible. When I taught algorithms, I observed that my students arrived lacking much of the background knowledge I would expect, but they more than compensated by being so bright. The engineers did about as well as comp-sci students. We all got blown away by a couple scary-smart math majors. You don't need to teach, or know, the visitor pattern. Deal with the the fundamentals. There are two ways we describe specific computational problems: output as a function of input, and abstract data type. Python is great for both. -- --Bryan -- http://mail.python.org/mailman/listinfo/python-list
Re: does anybody earn a living programming in python?
Hendrik van Rooyen [EMAIL PROTECTED] wrote in news:[EMAIL PROTECTED]: [...] Oh dont be so pedantic - countless - without count - probably just means that nobody has bothered to count them... Without being particularly pedantic: no, it doesn't. It means too many to count. Though I would have taken Anthony's usage (there's countless other people I know...) less than literally. -- rzed -- http://mail.python.org/mailman/listinfo/python-list
Re: Starting Win32 Service
Tim Golden wrote: ... Yes, sorry about that, it's a well-known (to me) gotcha. Basically there's no way I can extract the params from the COM interface in a way which implies order, so I can't take them in positionally. (Corrections to this statement will be gratefully received). TJG InParameters.Properties_ can be accessed by name or index, so you should be able to map both *args and **kwargs. (although you'd have to check for overlap yourself) Roger == Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News== http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups = East and West-Coast Server Farms - Total Privacy via Encryption = -- http://mail.python.org/mailman/listinfo/python-list
RE: Starting Win32 Service
| Tim Golden wrote: | ... | Yes, sorry about that, it's a well-known (to me) gotcha. | Basically there's no way I can extract the params from | the COM interface in a way which implies order, so I | can't take them in positionally. (Corrections to this | statement will be gratefully received). | | TJG | | InParameters.Properties_ can be accessed by name or index, | so you should be able to map both *args and **kwargs. | (although you'd have to check for overlap yourself) | | Roger Thanks a lot, Roger. I thought I'd looked around this one before, but obviously not hard enough! I'll have another look. TJG This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk -- http://mail.python.org/mailman/listinfo/python-list
Writing python extensions for libburn libisofs
Hello, If there is anyone familiar with python C api, and would like to get involved with writing python extensions for above two libs (http://libburn.pykix.org) please contact me. Kind regards, Mario -- http://mail.python.org/mailman/listinfo/python-list
Continuing after error
Hi, Does anyone know if it is possible to resume the execution of a program after it stops at an error in the code and the error was corrected? Sincerely, Sheldon -- http://mail.python.org/mailman/listinfo/python-list
Re: Continuing after error
Sheldon wrote: Hi, Does anyone know if it is possible to resume the execution of a program after it stops at an error in the code and the error was corrected? try: do something except SomeException: correct the error do something else i.e. you handle the error in the except clause. If that's successful, your program will continue normally. Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: License / Registration key enabled software
On Thu, 28 Sep 2006 10:19:37 +1000, Ben Finney wrote: For instance a customer might want to buy a license to use your software on up to 5 machines at once, but still have the software installed on every machine in the company. This need is adequately served by not imposing usage restrictions. Any effective imposition of usage restrictions is hostile to the wants of the user. Who is the user? The person who uses the software isn't always the same as the person who paid for it, or the person who'll be in trouble if the license terms aren't adhered to. Imagine you're an IT manager for a medium-to-large company who wants to use some expensive piece of software. You talk to the vendor and buy a licence to use the software on up to 5 machines at once, but you don't know who in the company will want to use it, so for convenience you want to install it on every PC in the building. Having installed it all over the shop, how can you be sure that only 5 people are using it at any one time? Do you expect your users to walk round the building asking everyone else if they're using the software, or are they more likely to just start it up and start working? Of course this argument really applies only to large, expensive commercial packages. I'd certainly agree that licence keys are often used inappropriately in a way which doesn't really benefit anyone, but this doesn't mean they don't have a place somewhere in the grand scheme of things. Mike -- http://mail.python.org/mailman/listinfo/python-list
Resuming a program's execution after correcting error
Hi. Does anyone know if one can resume a python script at the error point after the error is corrected? I have a large program that take forever if I have to restart from scratch everytime. The error was the data writing a file so it seemed such a waste if all the data was lost and must be recalculated again. Sincerely, Sheldon -- http://mail.python.org/mailman/listinfo/python-list
Re: License / Registration key enabled software
On Wed, 27 Sep 2006 12:21:08 -0500, Robert Kern wrote: Mike Playle wrote: For instance a customer might want to buy a license to use your software on up to 5 machines at once, but still have the software installed on every machine in the company. License systems like FlexLM can work here, to make it easier for them to ensure that they comply with the terms of the license. But then you must weigh that against the inconvenience that you impose upon your customers. Although you may make it easier for them to comply with your license, you are also making it harder for them to *use* your software. This is certainly true. As with any other software feature it's vital to weigh up the advantages against the disadvantages, and not blindly add features which don't provide a clear overall benefit. I do not know a single person who has used FlexLM-licensed software and does not hate FlexLM with a burning passion. Yup, I can agree with that. From the POV of the guy who just wants to get some work done, it's usually a real pain. His boss may have a different view of the matter, though. I've met people who've _bought_ FlexLM-licensed software who think it's the best thing since sliced bread. Mike -- http://mail.python.org/mailman/listinfo/python-list
Re: a query on sorting
Paul Rubin wrote: Gabriel Genellina [EMAIL PROTECTED] writes: sorted((x[1], x[0]) for x in enumerate(a)) [(1, 7), (2, 4), (2, 8), (3, 2), (4, 1), (5, 3), (6, 5), (7, 6), (9, 0)] Why forcing to use enumerate if it doesn't fit? And a generator won't help here since you have to access all the items. sorted([(a[i],i) for i in range(len(a))]) I think sorted((x,i) for i,x in enumerate(a)) looks nicer than the above. Indeed it does: an excellent refinement of my rather crappily-expressed original idea. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
On 28 Sep 2006, at 8:05 AM, [EMAIL PROTECTED] wrote: From: Bruno Desthuilliers [EMAIL PROTECTED] Subject: Re: Questions on Using Python to Teach Data Structures and Algorithms To: python-list@python.org Brendon Towle wrote: Some of your Lisp translations are subtly off... Seems correct to me. Lisp lists are linked lists, not arrays. Date: 28 Sep 2006 02:49:50 -0700 From: sturlamolden [EMAIL PROTECTED] Subject: Re: Questions on Using Python to Teach Data Structures and Algorithms To: python-list@python.org If you want to make a chained structure, then perhaps you know LISP? This is what the basic machinery of LISP looks like in Python: def cons(a,b) return [a,b] should be: return [a].extend(b) A Lisp cons is made of a reference to it's content and a reference to the rest of the list, so cons = lambda a, b : [a, b] seems the most straightforward translation. Yes, a lisp cons is a pair of references as you describe. However, the following lisp call: ? (cons item list) returns a single level list, with item as its new first item, and the original contents of list as the remainder of the list. The OP's code doesn't do that; it returns a list of two items, with list as the second item. To put it another way, the following code is always true in Lisp: ? (= (length (cons item list)) (1+ (length list))) But the OP's code only allows that to be true when list is of length 1. I suppose, of course, that you could claim that the following Lisp list: (1 2 3 4) should translate into the following Python list: [1, [2, [3, [4 But, I think that's a bit silly. def car(structure) return structure[0] def cdr(structure) return structure[1] should be: return structure[1:] idem. I should have pointed out, of course, that the original definition of CDR was correct given the original (incorrect) definition of cons. B. -- Brendon Towle, PhD Cognitive Scientist +1-412-690-2442x127 Carnegie Learning, Inc. The Cognitive Tutor Company ® Helping over 375,000 students in 1000 school districts succeed in math. -- http://mail.python.org/mailman/listinfo/python-list
Re: Top and Bottom Values [PEP: 326]
On 2006-09-28, Paul Rubin http wrote: Paul Rubin http://[EMAIL PROTECTED] writes: sys.maxint - 3 to sys.maxint + 7. I'm not sure tbl[:Top] would do what it is supposed to do in those circumstances. Top = object() class Table(list): ... Oh wait, I missed the : in your tbl[:Top] example. Yeah, you could hair up Table to account for slices, I'll leave the exercise to you. Yes, I could hair up Table, but that is missing the point somewhat. The idea for provinding extreme values is that you don't have to hair up the code. In any case it seems I have my answer. I have some suggestions I can try out, but writing up once own module for extreme values isn't as easy as is suggested in the rejection of the PEP and there is probably very little chance to get the PEP reopened. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Extra Newby question - Trying to create md5 File Listing
Gabriel and Dennis, than you for all your help. I ended up talking to
a friend a work about it and here's what we cam up with. It's very
similar to your suggestions so again, thanks. I just need to add a
machine name so I can get a md5 log from multiple machines and put it
in a database for version control monitoring.
Blessings, Jim.
#!/usr/bin/python
# Filename: md5makr.py
import sys
import os, os.path
import glob
import md5
import ConfigParser
config = ConfigParser.ConfigParser()
config.read('md5makr.ini')
outputfilname = config.get('general', 'outputfile')
f = file(outputfilname,'wt')
fileconfig = config.get('general', 'inputfiles')
# print 'fileconfig is ', fileconfig
fl = file(fileconfig,'r')
pathlist = [fli.strip() for fli in fl.readlines()]
# print 'fileData is ', fileData # so far so good
for p in pathlist:
filelist = glob.glob(p)
for fn in filelist:
data = file(fn,'rb').read()
hexstring = md5.md5(data).hexdigest()
f.write(fn + '\t' + hexstring + '\n')
f.close()
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Re: Resuming a program's execution after correcting error
Sheldon wrote: Hi. Does anyone know if one can resume a python script at the error point after the error is corrected? I have a large program that take forever if I have to restart from scratch everytime. The error was the data writing a file so it seemed such a waste if all the data was lost and must be recalculated again. As I said before, this can be done by finding out where the error is raised, what the cause is and by inserting an appropriate try-except-statement in the code. There's no way to do that without modifying the code, if the program itself doesn't offer such an option. Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: XSLT speed comparisons
Damian wrote:
Hi, I'm from an ASP.NET background an am considering making the switch
to Python. I decided to develop my next project in tandem to test the
waters and everything is working well, loving the language, etc.
What I've got is:
two websites, one in ASP.NET v2 and one in Python 2.5 (using 4suite for
XML/XSLT)
both on the same box (Windows Server 2003)
both using the same XML, XSLT, CSS
The problem is, the Python version is (at a guess) about three times
slower than the ASP one. I'm very new to the language and it's likely
that I'm doing something wrong here:
from os import environ
from Ft.Lib.Uri import OsPathToUri
from Ft.Xml import InputSource
from Ft.Xml.Xslt import Processor
def buildPage():
try:
xsluri = OsPathToUri('xsl/plainpage.xsl')
xmluri = OsPathToUri('website.xml')
xsl = InputSource.DefaultFactory.fromUri(xsluri)
xml = InputSource.DefaultFactory.fromUri(xmluri)
proc = Processor.Processor()
proc.appendStylesheet(xsl)
params = {url:environ['QUERY_STRING'].split(=)[1]}
for i, v in enumerate(environ['QUERY_STRING'].split(/)[1:]):
params[selected_section%s % (i + 1)] = / + v
return proc.run(xml, topLevelParams=params)
except:
return Error blah blah
print Content-Type: text/html\n\n
print buildPage()
You can compare the development sites here:
asp: http://consultum.pointy.co.nz/about/team
python: http://python.pointy.co.nz/about/team
Cheers!
For max speed you might want to try pyrxp:
http://www.reportlab.org/pyrxp.html
-Larry
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Re: windev vs python SOS
stéphane bard wrote: hello, my boss ask me to prefer windev to python. I have to argue - python work on multiple platform (linux, mac, windows) A good point but it didn't interest him. Because we want to choose a language for prototyping. So multi platform is not enough. - python and windev are fast to develop - windev as a good IDE, python? boa-constructor is ok with wxpython - python is open source (that's not an argument for my boss, sorry it's a boss ...) any idea for a strong argument ? You might argue that Python allows much better integration with other Windows functionality: see Robinson Hammond's Python Programming on Win32, and mention IronPython. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: OT: productivity and long computing delays
Paul Rubin wrote: [EMAIL PROTECTED] writes: Paul Anyway, I did the same build on a 2 ghz Athlon 64 and was Paul surprised that the speedup was only 35% or so. I'd have to get a Paul multiprocessor box to obtain really substantial gains. Maybe your build process is i/o bound. If you're using GNU make and have the make dependencies set up properly, the -jN flag (for N = 2 or 3) may speed things up. It's almost all CPU-bound on both the Pentium M and the Athlon. But I wasn't as much asking for technical approaches to speeding up calculation, as for general strategy about dealing with this downtime productively (I figured it was ok to ask this, given the other thread about RSI). My workday is getting chopped up in a manner sort of like memory fragmentation in a program, where you end up with a lot of disjoint free regions that are individually too small to use. As for the technical part, the underlying problem has to do with the build system. I should be able to edit a source file, type make and recompile just that file and maybe a few related ones. But the results of doing that are often incorrect, and to make sure the right thing happens I have to rebuild. I'm not in a position right now to start a side project to figure out what's wrong with the build system and fix it. Well why not study it while the build system is running? Needn't be a full-blown project, but it sounds like you might save yourself a lot of pain for relatively little effort. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: sqlite3 error
John Machin wrote: John Salerno wrote: CREATE TABLE Researchers ( researcherID varchar(9) PRIMARY KEY NOT NULL, birthYear int(4) DEFAULT NULL, birthMonth int(2) DEFAULT NULL, birthDay int(2) DEFAULT NULL, birthCountry varchar(50) DEFAULT NULL, birthState char(2) DEFAULT NULL, birthCity varchar(50) DEFAULT NULL, nameFirst varchar(50) NOT NULL, nameLast varchar(50) NOT NULL, nameGiven varchar(255) DEFAULT NULL, A bit OT, but one answer to the can you make a living with just Python question is Yup, tool of choice for rummaging in and fixing data that's been mangled by users cramming it into dodgy data models :-) (1) Consider that some countries have states/provinces with 3-letter abbreviations (e.g. Australia) or no abbreviation than I'm aware of in a Latin alphabet (e.g. China). Good point. I guess since this program is for my own use, I just figured I could stick with the American style abbreviation. But it's not as if I actually considered that this wouldn't always work, so it's good to be aware of the issue. (2) It's not apparent how you would use the first, last, and given names columns, especially with two of them being not null. Consider how you would store e.g.: J Edgar Hoover DJ Delorie Sukarno 35 Maggie Cheung Man-Yuk Molnar Janos Fatimah binte Rahman Zhang Manyu Not sure I follow you on some of these examples. In the case of J Edgar Hoover, I would just put the full name for his first name, or if J is entered, then just that, I suppose. Given name will be first name + middle name(s). (I took most of this schema from a baseball database, so maybe it's just something that worked better there.) -- http://mail.python.org/mailman/listinfo/python-list
Re: sqlite3 error
Dennis Lee Bieber wrote: On Wed, 27 Sep 2006 18:41:54 GMT, John Salerno [EMAIL PROTECTED] declaimed the following in comp.lang.python: You're right! I think that must have been leftover from when it wasn't the last line in the query. Thanks! You also, based upon the cutpaste, have a stray ) (or something similar in the last line) I don't see this. The code works now, though. Maybe it was something carried over by pasting. -- http://mail.python.org/mailman/listinfo/python-list
startswith() and endswith() for re's would be more intuitive
I just finished answering a question in #python because someone tried
to match using ... well.. match()
but did not realize that match() is actually startswith() for regexps.
I suggest:
re.compile('blah').atstartof(string)
re.compile('blah').atendof(string)
But it will never happen.
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remove the last character or the newline character?
Hello all: I have the following snippet: In [1]: fileName = 'Perfect Setup.txt\n' In [2]: fileName = fileName[0:len(fileName)-1)] # remove the '\n' character In [3]: fileName Out[3]: 'Perfect Setup.txt' Question one: Does python provide any function that can remove the last character of a string? I don't know whether or not the method I used is efficient Question two: Does python provide any function that can remove the newline character from a string if it exists? Thank very much! -Daniel -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
[EMAIL PROTECTED] wrote: efrat: [...] then why was the name list chosen? I'd too love to know why the wrong list name was chosen for them, instead of array. (Maybe because list is shorter, or because ABC called them lists...) I suspect it's because of their intrinsic one-dimensional nature. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: remove the last character or the newline character?
Daniel Mark wrote: Question one: Does python provide any function that can remove the last character of a string? I don't know whether or not the method I used is efficient Doing fileName[-1] lets you access the last character, but I'm not sure about removing it since strings are immutable. It would still probably be something like you did. Question two: Does python provide any function that can remove the newline character from a string if it exists? fileName = 'Perfect Setup.txt\n' fileName.strip() 'Perfect Setup.txt' Or you can use lstrip() or rstrip() to remove just the left or right side. -- http://mail.python.org/mailman/listinfo/python-list
Re: remove the last character or the newline character?
Daniel Mark wrote: Hello all: I have the following snippet: In [1]: fileName = 'Perfect Setup.txt\n' In [2]: fileName = fileName[0:len(fileName)-1)] # remove the '\n' character In [3]: fileName Out[3]: 'Perfect Setup.txt' Question one: Does python provide any function that can remove the last character of a string? I don't know whether or not the method I used is efficient fileName = fileName[:-1] Question two: Does python provide any function that can remove the newline character from a string if it exists? fileName = fileName.rstrip(\n) though this will remove more than one newline if present. If you only want to remove one newline, use if fileName[-1:] == '\n': fileName = fileName[:-1] Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: remove the last character or the newline character?
In [1]: fileName = 'Perfect Setup.txt\n'
In [2]: fileName = fileName[0:len(fileName)-1)] # remove the '\n'
character
In [3]: fileName
Out[3]: 'Perfect Setup.txt'
Question one:
Does python provide any function that can remove the last character of
a string?
I don't know whether or not the method I used is efficient
You're close...
fileName = fileName[0:-1]
which is the same as
fileName = fileName[:-1]
which will lop off the last character. Much nicer than most
other languages I've used where you have to use the len() trick
you're using. Also, it's a common python idiom you'll see
frequently.
Question two:
Does python provide any function that can remove the newline character
from a string if it exists?
In a discussion on this very matter a while back, I think the
final verdict was something like
fileName = fileName.rstrip('\n')
which will strip off *all* the trailing newlines. In most cases
(such as for line in file('foo.txt'): code), there's only one
to be stripped, so this works fine.
If you're ornary and want *only* the last '\n' lopped off, you'd
have to test for it:
if fileName[-1] == '\n': fileName = fileName[:-1]
There were caveats regarding \n vs. \r\n line endings, but if
the file comes in in ascii mode (rather than binary mode), Python
more or less smart enough to do the translation for you, leaving
the above code to work in the majority of cases.
-tkc
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Re: remove the last character or the newline character?
Daniel Mark wrote:
Hello all:
I have the following snippet:
In [1]: fileName = 'Perfect Setup.txt\n'
In [2]: fileName = fileName[0:len(fileName)-1)] # remove the '\n'
fileName = fileName.rstrip('\n')
or just a plain:
fileName = fileName.strip()
character
In [3]: fileName
Out[3]: 'Perfect Setup.txt'
Question one:
Does python provide any function that can remove the last character of
a string?
Not directly, since Python strings are immutable objects. If you want a
copy of the string without the last char *whatever it is*, you can just use
somestr = somestr[0:-1]
But in your situation, it's usually safer to use [lr]?strip()
Question two:
Does python provide any function that can remove the newline character
from a string if it exists?
Here again, you cannot *remove* anything from a string - you can just
have a modified copy copy of the string. (NB : answer is just above :
use str.strip())
HTH
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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best way to get data into a new instance?
Let's pretend I'm creating an Employee class, which I will later subclass for more specific jobs. Each instance will have stuff like a name, title, degrees held, etc. etc. So I'm wondering, is the best way to get all this information into the object to just have a really long __init__ method that takes each argument? Does a question like this depend on how the class will be used? I'm trying to construct it in a way that is independent of, say, the GUI interface that will be used, but I can't help but think that if all the data is entered into a GUI, then passed programmatically to the class, then it's no big deal because it happens behind the scenes. But if, for instance, someone manually created a new instance, they would have a ton of arguments to type in each time. Granted, even with the GUI they are basically typing in arguments, but in the manual case you'd have to type in the call to the class, the parentheses, commas, quotes around the strings, etc. (But still, I'm trying not to let a specific interface influence the construction of what should probably be a completely independent class implementation.) Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: startswith() and endswith() for re's would be more intuitive
metaperl wrote:
I just finished answering a question in #python because someone tried
to match using ... well.. match()
but did not realize that match() is actually startswith() for regexps.
Yet someone else that failed to read the Fine Manual(tm).
I suggest:
re.compile('blah').atstartof(string)
re.compile('blah').atendof(string)
What's wrong with:
re.search(r'^blah', somestring)
re.search(r'blah$', somestring)
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
--
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Re: remove the last character or the newline character?
Daniel Mark [EMAIL PROTECTED] wrote:
In [2]: fileName = fileName[0:len(fileName)-1)] # remove the '\n'
To chop the last character regardless of what it is:
fileName = fileName[:-1]
You don't need the 0 since thats the default, and you can use a negative
index instead of subtracting from len(x).
Question two:
Does python provide any function that can remove the newline character
from a string if it exists?
To remove all trailing whitespace:
fileName = fileName.rstrip()
to just remove a newline:
fileName = fileName.rstrip('\n')
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Re: remove the last character or the newline character?
Does python provide any function that can remove the newline character
from a string if it exists?
fileName = 'Perfect Setup.txt\n'
fileName.strip()
'Perfect Setup.txt'
Or you can use lstrip() or rstrip() to remove just the left or right side.
Just a caveat with the non-qualified strip/rstrip/lstrip...it
will remove *all* whitespace, so if, for some reason, it's
significant, and you only want to remove newlines, you have to
specify it:
s = ' some text \t\n'
s.strip()
'some text'
s.rstrip()
' some text'
s.rstrip('\n')
' some text \t'
As the OP was talking about file-names, the use of
initial/terminal spaces is allowable (albeit imprudent),
depending on your platform, so one may or may not want to strip
them off.
Fortunately, as in many other areas, Python offers the
flexibility in an easy-to-use way, and comes with sensible defaults.
-tkc
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Re: startswith() and endswith() for re's would be more intuitive
Bruno Desthuilliers wrote:
metaperl wrote:
I just finished answering a question in #python because someone tried
to match using ... well.. match()
but did not realize that match() is actually startswith() for regexps.
Yet someone else that failed to read the Fine Manual(tm).
I suggest:
re.compile('blah').atstartof(string)
re.compile('blah').atendof(string)
What's wrong with:
re.search(r'^blah', somestring)
re.search(r'blah$', somestring)
I think, since he even said himself that match() is actually
startswith() for regexps, that he isn't complaining about the lack of
this feature, just that he wants a name change. Otherwise I'm not sure
what he wants.
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Re: XSLT speed comparisons
Microsoft has put a lot of effort into their XML libraries as they are (or will be) the foundation of most of their software suites. I think you'll be hard pressed to find a library that exceeds it in both breadth of functionality and performance. Istvan -- http://mail.python.org/mailman/listinfo/python-list
Re: XSLT speed comparisons
Larry Bates wrote: Damian wrote: [...] What I've got is: two websites, one in ASP.NET v2 and one in Python 2.5 (using 4suite for XML/XSLT) both on the same box (Windows Server 2003) both using the same XML, XSLT, CSS The problem is, the Python version is (at a guess) about three times slower than the ASP one. I'm very new to the language and it's likely that I'm doing something wrong here: [...] For max speed you might want to try pyrxp: http://www.reportlab.org/pyrxp.html Except that pyrxp, to the best of my knowledge, is an XML parser and doesn't support XSLT, which is a requirement for Damian. Regards, Jan -- http://mail.python.org/mailman/listinfo/python-list
Re: best way to get data into a new instance?
John Salerno schrieb: Let's pretend I'm creating an Employee class, which I will later subclass for more specific jobs. Each instance will have stuff like a name, title, degrees held, etc. etc. So I'm wondering, is the best way to get all this information into the object to just have a really long __init__ method that takes each argument? Does a question like this depend on how the class will be used? I'm trying to construct it in a way that is independent of, say, the GUI interface that will be used, but I can't help but think that if all the data is entered into a GUI, then passed programmatically to the class, then it's no big deal because it happens behind the scenes. But if, for instance, someone manually created a new instance, they would have a ton of arguments to type in each time. Granted, even with the GUI they are basically typing in arguments, but in the manual case you'd have to type in the call to the class, the parentheses, commas, quotes around the strings, etc. (But still, I'm trying not to let a specific interface influence the construction of what should probably be a completely independent class implementation.) Who is typing? The programmer is responsible for the construction of new instances (or at least the code which will do that), and a constructor should contain parameters for at least the values you absolutely expect to be there - for example name and age or something like that in your example. You can of course always add attributes later. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Win95B
Ciarán Ó Duibhín wrote: I've just installed Python 2.5 under Win95B, and when run it says The PYTHON25.DLL file is linked to missing export KERNEL32.DLL.GetFileAttributesExA. Does Python 2.5 not run under Win95? If not, is there an earlier version of Python which does? Windows 95 was end-of-lifed by Microsoft five years ago: http://www.microsoft.com/windows/lifecycle/default.mspx I'm not sure that the last version that was officially tested with Windows 95 was, but Python 2.3 might work. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Can string formatting be used to convert an integer to its binary form ?
Mirco Wahab: But where is the %b in Python? Python doesn't have that. You can convert the number to a hex, and then map the hex digitds to binary strings using a dictionary, like this: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440528 Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list
Re: How to update my web automatically by python?
If you are in a dynamic web environment, then please post the components of that environment. If you only want to update your static web pages, look at ftplib, or scripting scp commands. [EMAIL PROTECTED] wrote: How to update my web automatically by python? I have one twiki web page https://twiki.cern.ch/twiki/bin/view/Atlas/CSC11DQ2ReplicateToCERNCAF In this page,the dates often need to be updated.Every time after I produce the dates ,I plaster the date to the web manual.The dates is produced by a python program.I want to write a python program to update my web automatically.I hope someone could help me.Tkanks!! -- Posted via a free Usenet account from http://www.teranews.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Finding the file referred to in a Python traceback
[EMAIL PROTECTED] wrote:
In this traceback, the path to 3 different SQL Alchemy source files is
a relative directory. However, no such directory is below my current
working directory.
Traceback (most recent call last):
File stdin, line 1, in ?
File conf/__init__.py, line 34, in __init__
self.table = tables(self.metadata)
File conf/__init__.py, line 38, in __init__
self.users = Table('Users', metadata, autoload=True)
File build/bdist.darwin-8.7.1-i386/egg/sqlalchemy/schema.py, line
138, in __call__
[etc]
print sys.path
['', '/sw/lib/python2.4/site-packages/Dabo-0.6.5s-py2.4.egg',
'/sw/lib/python2.4/site-packages/SQLAlchemy-0.2.8dev_r1898-py2.4.egg',
[etc]
Paths of files contained in eggs aren't always helpful (as was pointed
out to me recently). If you unzip the SQLAlchemy egg (eggs are just
zip files) (to somewhere other than site-packages if you want to avoid
confusion) you'll probably find schema.py etc. in there.
--
\S -- [EMAIL PROTECTED] -- http://www.chaos.org.uk/~sion/
___ | Frankly I have no feelings towards penguins one way or the other
\X/ |-- Arthur C. Clarke
her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump
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Re: best way to get data into a new instance?
So I'm wondering, is the best way to get all this information into the object to just have a really long __init__ method that takes each argument? As was pointed out, you might ask that absolutely essential information be passed to the constructor such as employee id#, but other then that, I think that it is more usual to do: class Employee: __init__(self, id): self.id = id e = Employee(32445) ... later e.firstname = 'foo' e.lastname = 'bar' ... more as the information comes about. -- Posted via a free Usenet account from http://www.teranews.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Battlefield Weapon Popularity Trend
In article [EMAIL PROTECTED], Mirco Wahab wrote: Thus spoke Chris Mattern (on 2006-09-27 19:09): In article [EMAIL PROTECTED], Mirco Wahab wrote: When the Samurai of medieval Japan were confronted with new 'battlefield language', e.g. early Shotguns, early Shotguns :D. Your mastery of the history of firearms overwhelms me. You want a fight? With a muzzle-loaded gun? Three shots for everybody -- 5 minutes time? BTW: (http://en.wikipedia.org/wiki/Musket) The date of the origin of muskets remains unknown, but they are mentioned as early as the late 15th century, and they were primarily designed for use by infantry. Muskets became obsolete by the middle of the 19th century, as rifles superseded them. Muskets are not shotguns. -- Christopher Mattern Which one you figure tracked us? The ugly one, sir. ...Could you be more specific? -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
Going back to the original question, a related question: does anybody know why there are so few books on data structures and algorithms that use Python? I remember that, at least ~ 12 years ago there were many (and very good) books that used Pascal for this topic. So when I did my own search for one in Python (just for my own consumption and enlightnment) and could only find the same one as the original poster of this thread [1], I was very surprised. No publishers have felt the need to fill this gap? Best, R. [1] http://thread.gmane.org/gmane.comp.python.general/486698/focus=486698 Data Structures and Algorithms with Object Oriented Design Patterns (http://www.brpreiss.com/books/opus7/html/book.html) and was surprised. -- Ramon Diaz-Uriarte Bioinformatics Unit Spanish National Cancer Centre (CNIO) http://ligarto.org/rdiaz -- http://mail.python.org/mailman/listinfo/python-list
Re: Whither binary search?
John Machin [EMAIL PROTECTED] wrote: Fredrik Lundh wrote: well, people tend to use dictionaries when they need to look things up quickly... ... like those paper dictionaries with the words in alphabetical order :-) ... where you'll notice that the really big ones are divided up into buckets (which just happen to be keyed on initial letter). Truth is that humans are lot better than computers at general insertion sort, and its lookup equivalent, whereas computers are much better at calculating hashes. So we each use a dictionary implementation that plays to our strengths. -- \S -- [EMAIL PROTECTED] -- http://www.chaos.org.uk/~sion/ ___ | Frankly I have no feelings towards penguins one way or the other \X/ |-- Arthur C. Clarke her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
Brendon Towle wrote:
On 28 Sep 2006, at 8:05 AM, [EMAIL PROTECTED] wrote:
From: Bruno Desthuilliers [EMAIL PROTECTED]
Brendon Towle wrote:
Some of your Lisp translations are subtly off...
Seems correct to me. Lisp lists are linked lists, not arrays.
From: sturlamolden [EMAIL PROTECTED]
If you want to make a chained structure, then perhaps you know LISP?
This is what the basic machinery of LISP looks like in Python:
def cons(a,b)
return [a,b]
should be:
return [a].extend(b)
A Lisp cons is made of a reference to it's content and a reference to
the rest of the list, so cons = lambda a, b : [a, b] seems the most
straightforward translation.
Yes, a lisp cons is a pair of references as you describe. However, the
following lisp call:
? (cons item list)
returns a single level list,
returns a single level *Lisp* list - ie, a linked list.
with item as its new first item, and the
original contents of list as the remainder of the list. The OP's code
doesn't do that; it returns a list of two items, with list as the
second item.
It returns a structure made of a reference to the new item and a
reference to the original list. Which is exactly what Lisp's cons does
AFAIK.
To put it another way, the following code is always true in Lisp:
? (= (length (cons item list)) (1+ (length list)))
But the OP's code only allows that to be true when list is of length 1.
Not if you're writing the appropriate length function:
def length(linkedlist):
return cdr(linkedlist) and 1 + length(cdr(linkedlist)) or 1
You obviously can't use the Python builtin len() here.
I suppose, of course, that you could claim that the following Lisp list:
(1 2 3 4)
should translate into the following Python list:
[1, [2, [3, [4
Should actually be
[1, [2, [3, [4, []
The internal representation of a Lisp list is really (1 (2 (3 (4 (),
not (1 2 3 4).
If it's the fact the proposed translation uses Python lists internally
that bother you, you could also implement it with a more heavyweight
solution:
class cons(object):
def __init__(self, car, cdr=None):
self.car = car
self.cdr = cdr
def __repr__(self):
return cons %s %s % (self.car, self.cdr)
def llist(*args):
alist = None
for item in reversed(args):
alist = cons(item, alist)
print alist
return alist
def cdr(acons):
return acons.cdr
def car(acons):
return acons.car
def length(llist):
if cdr(llist) is None:
return 1
return 1 + length(cdr(llist))
But, I think that's a bit silly.
It's *of course* a bit silly[1] - Python is not Lisp. But it's a clear
illustration of the difference between Python lists and Lisp lists !-)
[1] OTHO, using this with tuples may be (or may have been) a more
efficient implementation for stacks than plain Python lists, cf Mark
Lutz, Programming Python, 2nd edition.
def car(structure)
return structure[0]
def cdr(structure)
return structure[1]
should be:
return structure[1:]
idem.
I should have pointed out, of course, that the original definition of
CDR was correct given the original (incorrect) definition of cons.
The original definition of cons() was by no mean incorrect.
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: best way to get data into a new instance?
John Salerno wrote: So I'm wondering, is the best way to get all this information into the object to just have a really long __init__ method that takes each argument? really long __init__ argument lists only work if most argument have reasonable defaults, and you're prepared to use keyword arguments when creating the objects. and don't mind writing the field names over and over and over and over again. really long positional argument lists are really bad; it's way too easy to mess up the order, and end up stuffing the wrong thing in the wrong field. there's no need to use this if you're using the class as a record; just set the relevant attributes and be done with it. (see the simulate UI part of my code example for how to do that). /F -- http://mail.python.org/mailman/listinfo/python-list
Re: XML parser that sorts elements?
Paul McGuire wrote: doc.childNodes[0].childNodes = sorted( ... [n for n in doc.childNodes[0].childNodes ... if n.nodeType==doc.ELEMENT_NODE], ... key=lambda n:n.nodeName) print doc.toprettyxml() ?xml version=1.0 ? booga bar=2 foo=1 blah goodbye /blah well hello /well /booga My requirements changed a bit, so now I'm sorting second level elements by their values of a specific attribute (where the specific attribute can be chosen). But the solution is still mainly what you posted here. It was just a matter of supplying a different function for 'key'. It's up and running live now and all is well. Thanks again! (A bonus side effect of this is that it let me sneak sorted() into our test infrastructure, which gave me reason to get our IT guys to upgrade a mismash of surprisingly old Python versions up to Python 2.5 everywhere.) --JMike -- http://mail.python.org/mailman/listinfo/python-list
Re: best way to get data into a new instance?
John Salerno wrote:
Let's pretend I'm creating an Employee class, which I will later
subclass for more specific jobs.
Let's pretend it might be a good design... g
Each instance will have stuff like a
name, title, degrees held, etc. etc.
So I'm wondering, is the best way to get all this information into the
object to just have a really long __init__ method that takes each argument?
what about optional arguments ?
class Employee(object):
def __init__(self, id, name, **kw):
self.id = id
self.name = name
self.titles = kw.get('titles', [])
self.birthdate = kw.get(birthdate, None)
# etc
Does a question like this depend on how the class will be used?
I don't think it would make sens to design anything without any hint
about how it's supposed to be used.
My 2 cents
--
bruno desthuilliers
python -c print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])
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Re: for: else: - any practical uses for the else clause?
Ben Sizer [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Yeah, I use it from time to time: for foo in bar: if foo matches some condition: print sail to tahiti! break else: print abandon ship! As a C++ programmer (which I'm sure undermines my argument before you've even read it...), this feels 'backwards' to me. Although I am no purist, the 'else' typically implies failure of a previous explicit condition, yet in this case, it's executed by default, when the previous clause was successfully executed. It would seem more natural if the else clause was triggered by 'bar' being empty, [ ... ] It does: for foo in []: ... print foo ... else: ... print 'else' ... else I think it's clearer to see by comparing while with if: if False: do nothing else: do something while False: do nothing else: do something and getting to the for behaviour from while is trivial. That said, I've not had much call for it and was kind of surprised to find myself writing a genuine for ... else the other week. But it was the obvious way to do the task at hand, and I was happy it was there. -- \S -- [EMAIL PROTECTED] -- http://www.chaos.org.uk/~sion/ ___ | Frankly I have no feelings towards penguins one way or the other \X/ |-- Arthur C. Clarke her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
Ramon Diaz-Uriarte wrote: Going back to the original question, a related question: does anybody know why there are so few books on data structures and algorithms that use Python? Probably because Python has better than textbook implementations of core structures, and better than textbook implementations of many core algorithms, so lots of things can be done more efficiently by combining existing structures and algorithms than by using textbook algorithms. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: License / Registration key enabled software
Steve Holden enlightened us with: Otherwise you might as well say that any costs associated with using a piece of software (including purchase pricing) are hostile to the wants of the user. It's true. People pay because they have to, but they'd rather not. Sybren -- Sybren Stüvel Stüvel IT - http://www.stuvel.eu/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions on Using Python to Teach Data Structures and Algorithms
Brendon Towle wrote: Some of your Lisp translations are subtly off... Date: 28 Sep 2006 02:49:50 -0700 From: sturlamolden [EMAIL PROTECTED] Subject: Re: Questions on Using Python to Teach Data Structures and Algorithms To: python-list@python.org If you want to make a chained structure, then perhaps you know LISP? This is what the basic machinery of LISP looks like in Python: def cons(a,b) return [a,b] should be: return [a].extend(b) But surely this will return None? regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: License / Registration key enabled software
Mike Playle enlightened us with: Imagine you're an IT manager for a medium-to-large company who wants to use some expensive piece of software. You talk to the vendor and buy a licence to use the software on up to 5 machines at once, but you don't know who in the company will want to use it, so for convenience you want to install it on every PC in the building. Having installed it all over the shop, how can you be sure that only 5 people are using it at any one time? Write the software in such a way that it needs a certificate on a smartcard, then supply the company with five smartcards. Sybren -- Sybren Stüvel Stüvel IT - http://www.stuvel.eu/ -- http://mail.python.org/mailman/listinfo/python-list
Re: best way to get data into a new instance?
John Salerno wrote: Let's pretend I'm creating an Employee class, which I will later subclass for more specific jobs. Each instance will have stuff like a name, title, degrees held, etc. etc. So I'm wondering, is the best way to get all this information into the object to just have a really long __init__ method that takes each argument? Does a question like this depend on how the class will be used? I'm trying to construct it in a way that is independent of, say, the GUI interface that will be used, but I can't help but think that if all the data is entered into a GUI, then passed programmatically to the class, then it's no big deal because it happens behind the scenes. But if, for instance, someone manually created a new instance, they would have a ton of arguments to type in each time. Granted, even with the GUI they are basically typing in arguments, but in the manual case you'd have to type in the call to the class, the parentheses, commas, quotes around the strings, etc. (But still, I'm trying not to let a specific interface influence the construction of what should probably be a completely independent class implementation.) Thanks. Thanks again guys! I guess I'm letting all these little getting started questions hang me up too much. I should just start coding like Fredrik suggested ages ago and find out the bad design ideas for myself. :) Right now I started messing around with designing the GUI that will be used to input the data. It's much easier, I guess because it's just a matter of *doing* and not really figuring things out, but that's also why it gets tedious rather quickly! -- http://mail.python.org/mailman/listinfo/python-list
Re: Whither binary search?
On 2006-09-28, Sion Arrowsmith [EMAIL PROTECTED] wrote: John Machin [EMAIL PROTECTED] wrote: Fredrik Lundh wrote: well, people tend to use dictionaries when they need to look things up quickly... ... like those paper dictionaries with the words in alphabetical order :-) ... where you'll notice that the really big ones are divided up into buckets (which just happen to be keyed on initial letter). Truth is that humans are lot better than computers at general insertion sort, and its lookup equivalent, whereas computers are much better at calculating hashes. So we each use a dictionary implementation that plays to our strengths. Thanks all, for the help. In the end, perhaps prophetically, it turned out my data wasn't really fully sorted after all. I put together a short function to translate my raw data into a dictionary, and that was the end of my problem. -- Neil Cerutti -- http://mail.python.org/mailman/listinfo/python-list
Re: License / Registration key enabled software
Sybren Stuvel wrote: Mike Playle enlightened us with: Imagine you're an IT manager for a medium-to-large company who wants to use some expensive piece of software. You talk to the vendor and buy a licence to use the software on up to 5 machines at once, but you don't know who in the company will want to use it, so for convenience you want to install it on every PC in the building. Having installed it all over the shop, how can you be sure that only 5 people are using it at any one time? Write the software in such a way that it needs a certificate on a smartcard, then supply the company with five smartcards. And you guarantee that the contents of the smartcard is only used by one user at a time by building a licensing system for the smartcards? regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden -- http://mail.python.org/mailman/listinfo/python-list
Re: windev vs python SOS
stéphane bard wrote: hello, my boss ask me to prefer windev to python. I have to argue - python work on multiple platform (linux, mac, windows) A good point but it didn't interest him. Because we want to choose a language for prototyping. So multi platform is not enough. - python and windev are fast to develop - windev as a good IDE, python? boa-constructor is ok with wxpython - python is open source (that's not an argument for my boss, sorry it's a boss ...) any idea for a strong argument ? Python is widely known and tested, windev is not. Stuff not widely used (and thus not well verified by Real World(tm)) is a Big Business Risk(tm). Things looking pretty on marketing presentations might show its ugly head in Real Life(tm) where Real Money(tm) is at stake (and in fact they do in vast majority of cases). Python is widely known and has Good Track Record(tm). Windev has not. Python is known to integrate well into Windows. Is your boss really sure that windev is good there? How about various corner cases? Does your boss know about .net? Tell him about IronPython (If Microsoft thinks its good, why your boss should not?). If your boss thinks .net is crap and Java rules, tell him about Jython. It's relatively easy to find (hire) Python programmers. It's not true in case of windev programmers. If your boss needs more people or some people leave (and thus must be replaced), it's a Real Cost(tm) to train new people new windev tricks. Is your boss willing to take the risk that new people will need 1-2 months to get fluent with windev (as he may well forget about hiring trained windev developer in a reasonable amount of time, while hiring trained python developer is possible). rgds -- Sebastian Kaliszewski -- http://mail.python.org/mailman/listinfo/python-list
Re: XSLT speed comparisons
Jan Dries wrote: Larry Bates wrote: Damian wrote: [...] What I've got is: two websites, one in ASP.NET v2 and one in Python 2.5 (using 4suite for XML/XSLT) both on the same box (Windows Server 2003) both using the same XML, XSLT, CSS The problem is, the Python version is (at a guess) about three times slower than the ASP one. I'm very new to the language and it's likely that I'm doing something wrong here: [...] For max speed you might want to try pyrxp: http://www.reportlab.org/pyrxp.html Except that pyrxp, to the best of my knowledge, is an XML parser and doesn't support XSLT, which is a requirement for Damian. Regards, Jan Oops, I should have read the OPs post closer. -Larry -- http://mail.python.org/mailman/listinfo/python-list
