date:20140103


On 1/2/2014 8:20 PM, Mark Lawrence wrote:

On 03/01/2014 00:57, Gary Herron wrote:

On 01/02/2014 01:44 PM, John Allsup wrote:

The point of my original post was that, whilst C's
  if( x = 2 ) { do something }
and
  if( x == 2 ) { do something }
are easy to confuse, and a source of bugs, having a construct like
follows:

if x == 2:
do something # what happens at present
if testFunc() as x:
do something with x

using the 'as' syntax that appears with 'with' and 'except', would allow
for the advantages of C style assignments in conditionals but without
the easy confusion, since here the syntax is significantly different
between assignment and equality testing (rather than a character apart
as happens with C).

This occurs further down in my original post (past the point where you
inserted your reply).

Another post suggested a workaround by defining a 'pocket' class, for
which I am grateful.

John


Sorry.  I shot off my answer before reading the whole post.  That's
never a good idea.


After reading to the end, I rather like your suggestion.  It works well
in your example, , nicely avoids the C/C++ trap, and has some
consistency with other parts of Python.

Gary Herron




I liked the look of this as well.  It ought to go to python ideas, or
has it been suggested there in the past?


Yes, and rejected (I am quite sure). Consistency would 'demand' at least 
while expr as target and possibly for i in iterable_expr as target.



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Debugging on the Mac question.

Team,


I am a Vision Impaired programmer on the Mac and Window platforms. I have 
started to learn Python. The biggest road block I have is the ability of 
debugging my simple scripts. The IDLE program does not work with the screen 
readers I use on the Mac or Windows. A screen reader is a program that grabs 
the text on the screen and converts it into speech output, at least this is the 
5 feet explanation.  I cannot see the screen at all.

I have looked at eclipse and it doesn't work with Voice-Over (the screen reader 
on the Mac). I have java issues on my windows machine preventing me running 
this app.

If I use $python -d script.py the debugger doesn't seem to trigger on the mac. 

So how I can perform a debug on a script so I can step through it, set up break 
points, watch variables, etc. 

It is really annoying me, since under Perl I just added the -d switch and had a 
full debugger that worked at the console level.

Sean 
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Re: Blog about python 3


On 1/2/2014 11:49 PM, Steven D'Aprano wrote:

Robin Becker wrote:


For fairly sensible reasons we changed the internal default to use unicode
rather than bytes. After doing all that and making the tests compatible
etc etc I have a version which runs in both and passes all its tests.
However, for whatever reason the python 3.3 version runs slower


For whatever reason is right, unfortunately there's no real way to tell
from the limited information you give what that might be.

Are you comparing a 2.7 wide or narrow build? Do your tests use any
so-called astral characters (characters in the Supplementary Multilingual
Planes, i.e. characters with ord()  0x)?

If I remember correctly, some early alpha(?) versions of Python 3.3
consistently ran Unicode operations a small but measurable amount slower
than 3.2 or 2.7. That especially effected Windows. But I understand that
this was sped up in the release version of 3.3.


There was more speedup in 3.3.2 and possibly even more in 3.3.3, so OP 
should run the latter.


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Re: Debugging on the Mac question.

2014-01-03 Thread Paul Rudin

Sean Murphy mhysnm1...@gmail.com writes:


 I am a Vision Impaired programmer on the Mac and Window platforms. I have
 started to learn Python. The biggest road block I have is the ability of
 debugging my simple scripts. The IDLE program does not work with the screen
 readers I use on the Mac or Windows. A screen reader is a program that grabs
 the text on the screen and converts it into speech output, at least this is 
 the
 5 feet explanation.  I cannot see the screen at all.

 I have looked at eclipse and it doesn't work with Voice-Over (the screen 
 reader
 on the Mac). I have java issues on my windows machine preventing me running
 this app.

 If I use $python -d script.py the debugger doesn't seem to trigger on the 
 mac. 

 So how I can perform a debug on a script so I can step through it, set up 
 break
 points, watch variables, etc.

 It is really annoying me, since under Perl I just added the -d switch and had 
 a
 full debugger that worked at the console level.

For command line debugging see
http://docs.python.org/3/library/pdb.html. 


More generally you might want to investigate
http://emacspeak.sourceforge.net/ (disclaimer - I have never used
this, but from what you say you might find it useful).
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Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Chris Seberino

I've heard it said, by no less a guru than Peter Norvig, that Python is a lot 
like Lisp without the parentheses at least for the basics of Python.

For pedagogical reasons, I'm wondering if it would be easy to implement a big 
subset of Python in Scheme.  

The basics of Scheme or Lisp are amazingly easy to implement.  Would 
implementing a subset of Python in a Scheme subset be a clever way to easily 
implement a lot of Python?

(This isn't for practical reasonsI'm just curious.)

Chris
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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Rustom Mody

On Fri, Jan 3, 2014 at 12:16 PM, Chris Seberino cseber...@gmail.com wrote:
 I've heard it said, by no less a guru than Peter Norvig, that Python is a lot 
 like Lisp without the parentheses at least for the basics of Python.

 For pedagogical reasons, I'm wondering if it would be easy to implement a big 
 subset of Python in Scheme.

 The basics of Scheme or Lisp are amazingly easy to implement.

Because parsing and unparsing (aka printing) are so trivial for s-expressions

 Would implementing a subset of Python in a Scheme subset be a clever way
 to easily implement a lot of Python?

At the innards of lisp and python are garbage collected data structures.
Building one with the other gets you that for free
[Doing it in a lower level language like C is what invokes the humorous:
Greenspuns tenth law]
So yes in that one respect what you say is true.
But then theres also (apart from parsing) all kinds of semantic differences eg:
- exceptions
- modules
- OOP milarky
- C interfacing in Baskin Robbins number of flavours
- carefully crafted portable veneer on top of intrinsically non portable OSes

All these have to be handled one way or other


 (This isn't for practical reasonsI'm just curious.)

A crucial difference between python and lisp is that python is
practical and lisp is utopian
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Re: Blog about python 3

2014-01-03 Thread wxjmfauth

It's time to understand the Character Encoding Models
and the math behind it.
Unicode does not differ from any other coding scheme.

How? With a sheet of paper and a pencil.

jmf
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Re: Blog about python 3

On Fri, Jan 3, 2014 at 9:10 PM,  wxjmfa...@gmail.com wrote:
 It's time to understand the Character Encoding Models
 and the math behind it.
 Unicode does not differ from any other coding scheme.

 How? With a sheet of paper and a pencil.


One plus one is two, therefore Python is better than Haskell.

Four times five is twelve, and four times six is thirteen, and four
times seven is enough to make Alice think she's Mabel, and London is
the capital of Paris, and the crocodile cheerfully grins. Therefore,
by obvious analogy, Unicode times new-style classes equals a 64-bit
process.

I worked that out with a sheet of paper and a pencil. The pencil was a
little help, but the paper was three sheets in the wind.

ChrisA
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Re: Blog about python 3


On 02/01/2014 18:25, David Hutto wrote:

Just because it's 3.3 doesn't matter...the main interest is in
compatibility. Secondly, you used just one piece of code, which could be a
fluke, try others, and check the PEP. You need to realize that evebn the
older versions are benig worked on, and they have to be refined. So if you
have a problem, use the older and import from the future would be my
suggestion


Suggesting that I use another piece of code to test python3 against python2 is a 
bit silly. I'm sure I can find stuff which runs faster under python3, but 
reportlab is the code I'm porting and that is going the wrong way.

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Re: On a scrollbar for tkinter

2014-01-03 Thread Vlastimil Brom

2014/1/3  eneskri...@gmail.com:
 @Rick
 I found some solutions for python 2.x, but still, as I am with the future, I 
 need a futuristic solution or 2, so if anyone else could help me, I'd be 
 grateful!
 --

Hi,
I usually don't use tkinter myself, hence others may have more
idiomatic suggestions,
but you can of course use ScrolledWindow  tix with python3; cf.:

from tkinter import tix

root = tix.Tk()
root.title(scrolled window)
root.geometry(50x500+50+50)
sw= tix.ScrolledWindow(root)
sw.pack(fill=tix.BOTH, expand=1)
for i in range(1,101):
cb = tix.Checkbutton(sw.window, text=str(i))
cb.pack(fill=tix.BOTH, expand=0)
root.mainloop()

hth,
  vbr
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Re: Blog about python 3


On 02/01/2014 18:37, Terry Reedy wrote:

On 1/2/2014 12:36 PM, Robin Becker wrote:


I just spent a large amount of effort porting reportlab to a version
which works with both python2.7 and python3.3. I have a large number of
functions etc which handle the conversions that differ between the two
pythons.


I am imagine that this was not fun.


indeed :)



For fairly sensible reasons we changed the internal default to use
unicode rather than bytes.


Do you mean 'from __future__ import unicode_literals'?


No, previously we had default of utf8 encoded strings in the lower levels of the 
code and we accepted either unicode or utf8 string literals as inputs to text 
functions. As part of the port process we made the decision to change from 
default utf8 str (bytes) to default unicode.



Am I correct in thinking that this change increases the capabilities of
reportlab? For instance, easily producing an article with abstracts in English,
Arabic, Russian, and Chinese?

It's made no real difference to what we are able to produce or accept since utf8 
or unicode can encode anything in the input and what can be produced depends on 
fonts mainly.



  After doing all that and making the tests

...

I know some of these tests are fairly variable, but even for simple
things like paragraph parsing 3.3 seems to be slower. Since both use
unicode internally it can't be that can it, or is python 2.7's unicode
faster?


The new unicode implementation in 3.3 is faster for some operations and slower
for others. It is definitely more space efficient, especially compared to a wide
build system. It is definitely less buggy, especially compared to a narrow build
system.

Do your tests use any astral (non-BMP) chars? If so, do they pass on narrow 2.7
builds (like on Windows)?


I'm not sure if we have any non-bmp characters in the tests. Simple CJK etc etc 
for the most part. I'm fairly certain we don't have any ability to handle 
composed glyphs (multi-codepoint) etc etc






For one thing, indexing and slicing just works on all machines for all unicode
strings. Code for 2.7 and 3.3 either a) does not index or slice, b) does not
work for all text on 2.7 narrow builds, or c) has extra conditional code only
for 2.7.



probably
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Re: Blog about python 3


On 02/01/2014 23:57, Antoine Pitrou wrote:



..


Running a test suite is a completely broken benchmarking methodology.
You should isolate workloads you are interested in and write a benchmark
simulating them.



I'm certain you're right, but individual bits of code like generating our 
reference manual also appear to be slower in 3.3.



Regards

Antoine.





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WebSocket for Python 2 and 3 on Twisted and asyncio

2014-01-03 Thread Tobias Oberstein

Hi,

Autobahn provides open-source implementations of

* The WebSocket Protocol
* The Web Application Messaging Protocol (WAMP)

https://github.com/tavendo/AutobahnPython
https://pypi.python.org/pypi/autobahn

Starting with the release 0.7.0, Autobahn now fully supports (with all 
features) both

* Twisted (on Python 2/3) and
* asyncio (on Python 3.3+)

as the underlying networking framework.

Here is a complete example of WebSocket server and client:

Twisted:
https://github.com/tavendo/AutobahnPython/tree/master/examples/twisted/websocket/echo

Asyncio:
https://github.com/tavendo/AutobahnPython/tree/master/examples/asyncio/websocket/echo

The application code is very similar or even identical.

Cheers,
/Tobias
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pip's wheel support requires setuptools = 0.8 for dist-info support

2014-01-03 Thread seaders

I have a Jenkins server running Ubuntu which has been running perfectly fine 
for as long as I've been using it, and in one of the jobs, it runs a few things 
under the shiningpanda plugin (a python virtual environment wrapper).

At some point today, or over the weekend, the job that uses it started failing, 
with the main error seemingly being the title, full error reported is

   pip install Jinja2
  Wheel installs require setuptools = 0.8 for dist-info support.
  pip's wheel support requires setuptools = 0.8 for dist-info support.

I've googled for this error, or anything like it, but I haven't been able to 
find anything useful towards solving it.
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Re: Blog about python 3


On 03/01/2014 09:01, Terry Reedy wrote:

There was more speedup in 3.3.2 and possibly even more in 3.3.3, so OP
should run the latter.


python 3.3.3 is what I use on windows. As for astral / non-bmp etc etc that's 
almost irrelevant for the sort of tests we're doing which are mostly simple 
english text.

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Re: Debugging on the Mac question.

2014-01-03 Thread Robert Kern


On 2014-01-03 04:17, Sean Murphy wrote:

Team,


I am a Vision Impaired programmer on the Mac and Window platforms. I have 
started to learn Python. The biggest road block I have is the ability of 
debugging my simple scripts. The IDLE program does not work with the screen 
readers I use on the Mac or Windows. A screen reader is a program that grabs 
the text on the screen and converts it into speech output, at least this is the 
5 feet explanation.  I cannot see the screen at all.

I have looked at eclipse and it doesn't work with Voice-Over (the screen reader 
on the Mac). I have java issues on my windows machine preventing me running 
this app.

If I use $python -d script.py the debugger doesn't seem to trigger on the mac.

So how I can perform a debug on a script so I can step through it, set up break 
points, watch variables, etc.

It is really annoying me, since under Perl I just added the -d switch and had a 
full debugger that worked at the console level.


Python also has a console debugger. -d does not invoke it; -d is for something 
else.

  $ python -m pdb myscript.py

http://docs.python.org/3.3/library/pdb

--
Robert Kern

I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth.
  -- Umberto Eco

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Re: Blog about python 3

In article mailman.4850.1388752146.18130.python-l...@python.org,
 Robin Becker ro...@reportlab.com wrote:

 On 03/01/2014 09:01, Terry Reedy wrote:
  There was more speedup in 3.3.2 and possibly even more in 3.3.3, so OP
  should run the latter.
 
 python 3.3.3 is what I use on windows. As for astral / non-bmp etc etc that's 
 almost irrelevant for the sort of tests we're doing which are mostly simple 
 english text.

The sad part is, if you're accepting any text from external sources, you 
need to be able to deal with astral.

I was doing a project a while ago importing 20-something million records 
into a MySQL database.  Little did I know that FOUR of those records 
contained astral characters (which MySQL, at least the version I was 
using, couldn't handle).

My way of dealing with those records was to nuke them.  Longer term we 
ended up switching to Postgress.
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Creating a list with holes

I think I know the answer is no, but is there any package that allows
creating a list with holes in it? E.g. I'd want to do something like:

x[10] = 12
x[20] = 30

I'm thinking of something like defaultdict but for lists (I know
that's very different, but ... )

Thanks!
-larry
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Re: Creating a list with holes

2014-01-03 Thread eneskristo

On Friday, January 3, 2014 4:19:09 PM UTC+1, larry@gmail.com wrote:
 I think I know the answer is no, but is there any package that allows
 
 creating a list with holes in it? E.g. I'd want to do something like:
 
 
 
 x[10] = 12
 
 x[20] = 30
 
 
 
 I'm thinking of something like defaultdict but for lists (I know
 
 that's very different, but ... )
 
 
 
 Thanks!
 
 -larry

Hello Larry!

The thing is, where to put the holes? A costum function can be made if you want 
the hole to be placed for example:
1. In random
2. Every nth hole(Or with another sequence)
3. In the beginning or end.

Please tell me how do you want them, and I will try my best to help!
- Enes
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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 2:19 AM, Larry Martell larry.mart...@gmail.com wrote:
 I think I know the answer is no, but is there any package that allows
 creating a list with holes in it? E.g. I'd want to do something like:

 x[10] = 12
 x[20] = 30

 I'm thinking of something like defaultdict but for lists (I know
 that's very different, but ... )

Depending on what exactly you need, it's probably worth just using a
dict. In what ways do you need it to function as a list? You can
always iterate over sorted(some_dict.keys()) if you need to run
through them in order.

Alternatively, if you expect to fill in most of the elements, it's
possible you'd be happier working with a subclass of list that
auto-expands by filling in the spare space with a singleton meaning
no element here. The code probably exists somewhere, but if not, it
wouldn't be hard to write. Then it'd be a list, but you can start with
it empty and assign as you describe above.

What's the use case? I expect that one or the other of those options
would cover most cases, but maybe yours is different.

ChrisA
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Re: Creating a list with holes

In article mailman.4852.1388762356.18130.python-l...@python.org,
 Larry Martell larry.mart...@gmail.com wrote:

 I think I know the answer is no, but is there any package that allows
 creating a list with holes in it? E.g. I'd want to do something like:
 
 x[10] = 12
 x[20] = 30

Whenever you ask, What data structure do I want, you need to be able 
to answer, What operations do I want to perform?, and, What 
constraints do I have on memory use?

Why do you want holes?  Is the issue that you're storing sparse data and 
don't want to waste memory on unused keys?  If so, a dictionary should 
do you fine.

Do you need to be able to read the values back out in a specific order?  
You can still do that with a dictionary if you're willing to re-sort the 
keys; that's O(n log n) on the number of keys, but if n is small, it 
doesn't matter.
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Re: need to print seconds from the epoch including the millisecond

On Sat, Jan 4, 2014 at 2:33 AM, Grant Edwards invalid@invalid.invalid wrote:
 time.time() returns a Python float. A Python float will have 16 digits
 of precision. Perhaps the OS always sets some of those digits to 0 (or
 even random values), but they're still there.  Perhaps the accuracy or
 granularity of the values returned is problematic on some OSes, but
 the precision of the value doesn't change: there's no way he's only
 getting 2 decimal places from time.time() unless (as you mention
 below) he's printing them using a method that truncates/rounds.

If I print out the value float(1.01), I get just three digits. When
those trailing digits are all zeroes, they won't be displayed. That's
exactly what the OP was seeing.

ChrisA
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Re: Creating a list with holes

On Fri, Jan 3, 2014 at 10:30 AM,  eneskri...@gmail.com wrote:
 On Friday, January 3, 2014 4:19:09 PM UTC+1, larry@gmail.com wrote:
 I think I know the answer is no, but is there any package that allows

 creating a list with holes in it? E.g. I'd want to do something like:

 x[10] = 12
 x[20] = 30

 I'm thinking of something like defaultdict but for lists (I know

 that's very different, but ... )

 Hello Larry!

 The thing is, where to put the holes? A costum function can be made if you 
 want the hole to be placed for example:
 1. In random
 2. Every nth hole(Or with another sequence)
 3. In the beginning or end.

 Please tell me how do you want them, and I will try my best to help!

The holes would be between the items I put in. In my example above, if
I assigned to [10] and [20], then the other items ([0..9] and
[11..19]) would have None.
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Re: need to print seconds from the epoch including the millisecond

2014-01-03 Thread Grant Edwards

On 2014-01-03, Dave Angel da...@davea.name wrote:
 On Thu, 2 Jan 2014 16:23:22 + (UTC), Grant Edwards 
invalid@invalid.invalid wrote:
 AFAIK, that's irrelevent.  time.time() returns a float.  On all the
 CPython implementations I know of, that is a 64-bit IEEE format, 
 which provides 16 decimal digits of precision regardless of the 
 granularity of the system time value.  At this point in time, that
 means 10 digits left of the decimal point and 6 to the right.

 Correction: no more than about 6 to the right.  You can certainly get 
 less, from an os with a smaller resolution.

time.time() returns a Python float. A Python float will have 16 digits
of precision. Perhaps the OS always sets some of those digits to 0 (or
even random values), but they're still there.  Perhaps the accuracy or
granularity of the values returned is problematic on some OSes, but
the precision of the value doesn't change: there's no way he's only
getting 2 decimal places from time.time() unless (as you mention
below) he's printing them using a method that truncates/rounds.

 Or you can lose some of what you do get by printing in a sub-optimal
 way.

Yes, depending on how you print the value, you can hide some of the
digits.  But, there's no way for time.time() to return a value with
less than ~16 decimal digits of precicsion.

-- 
Grant Edwards   grant.b.edwardsYow! !  Everybody out of
  at   the GENETIC POOL!
  gmail.com
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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 2:38 AM, Roy Smith r...@panix.com wrote:
 Why do you want holes?  Is the issue that you're storing sparse data and
 don't want to waste memory on unused keys?  If so, a dictionary should
 do you fine.

 Do you need to be able to read the values back out in a specific order?
 You can still do that with a dictionary if you're willing to re-sort the
 keys; that's O(n log n) on the number of keys, but if n is small, it
 doesn't matter.

There's another factor, which is iteration time. Maybe you don't care
about the memory usage, but compare these:

foo = [None]*1000
foo[123] = 234
foo[543] = 432

for key,value in enumerate(foo):
if value: print(Slot %d is %d%(key,value))

# versus

foo = {}
foo[123] = 234
foo[543] = 432

for key in sorted(foo.keys()):
value = foo[key]
if value: print(Slot %d is %d%(key,value))

Which one's going to be faster? The dictionary, by far, in this
example. I'm not sure how populated the list would have to be to beat
it (as the dict will get slower on O(n log n) on keys, as you mention,
while the list will run at O(n) on the highest element, which may well
be a constant), but it's something to consider.

ChrisA
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Re: Blog about python 3

On Sat, Jan 4, 2014 at 1:57 AM, Roy Smith r...@panix.com wrote:
 I was doing a project a while ago importing 20-something million records
 into a MySQL database.  Little did I know that FOUR of those records
 contained astral characters (which MySQL, at least the version I was
 using, couldn't handle).

 My way of dealing with those records was to nuke them.  Longer term we
 ended up switching to Postgress.

Look! Postgres means you don't lose data!!

Seriously though, that's a much better long-term solution than
destroying data. But MySQL does support the full Unicode range - just
not in its UTF8 type. You have to specify UTF8MB4 - that is,
maximum bytes 4 rather than the default of 3. According to [1], the
UTF8MB4 encoding is stored as UTF-16, and UTF8 is stored as UCS-2. And
according to [2], it's even possible to explicitly choose the
mindblowing behaviour of UCS-2 for a data type that calls itself
UTF8, so that a vague theoretical subsequent version of MySQL might
be able to make UTF8 mean UTF-8, and people can choose to use the
other alias.

To my mind, this is a bug with backward-compatibility concerns. That
means it can't be fixed in a point release. Fine. But the behaviour
change is this used to throw an error, now it works. Surely that can
be fixed in the next release. Or surely a version or two of
deprecating UTF8 in favour of the two MB? types (and never ever
returning UTF8 from any query), followed by a reintroduction of
UTF8 as an alias for MB4, and the deprecation of MB3. Or am I
spoiled by the quality of Python (and other) version numbering, where
I can (largely) depend on functionality not changing in point
releases?

ChrisA

[1] http://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8mb4.html
[2] http://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8mb3.html
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Re: Creating a list with holes

On Fri, Jan 3, 2014 at 10:37 AM, Chris Angelico ros...@gmail.com wrote:
 On Sat, Jan 4, 2014 at 2:19 AM, Larry Martell larry.mart...@gmail.com wrote:
 I think I know the answer is no, but is there any package that allows
 creating a list with holes in it? E.g. I'd want to do something like:

 x[10] = 12
 x[20] = 30

 I'm thinking of something like defaultdict but for lists (I know
 that's very different, but ... )

 Depending on what exactly you need, it's probably worth just using a
 dict. In what ways do you need it to function as a list? You can
 always iterate over sorted(some_dict.keys()) if you need to run
 through them in order.

 Alternatively, if you expect to fill in most of the elements, it's
 possible you'd be happier working with a subclass of list that
 auto-expands by filling in the spare space with a singleton meaning
 no element here. The code probably exists somewhere, but if not, it
 wouldn't be hard to write. Then it'd be a list, but you can start with
 it empty and assign as you describe above.

 What's the use case? I expect that one or the other of those options
 would cover most cases, but maybe yours is different.

Yeah, googled and didn't find anything, then started writing it myself
last night, then this morning decided to ask if it already existed.

The use case is that I'm parsing a XML file like this:

  Parameter Name=DefaultVersion
Values
  Value
DefaultTrue/Default
  /Value
/Values
Values
  Value
CurrentFalse/Current
  /Value
/Values
Values
  Value
DefaultTrue/Default
CurrentFalse/Current
  /Value
/Values
Values
  DefaultTrue/Default
/Values

This is an existing program that is putting the data into a dict. The
dict keys are ['DefaultVersion','Default'] and
['DefaultVersion','Current']. These contain lists that have the
True/False values. It's currently not correctly handling the missing
items so it ends up with:

['DefaultVersion','Default'][0] = True
['DefaultVersion','Default'][1] = True
['DefaultVersion','Current'][0] = False

When it should be:

['DefaultVersion','Default'][0] = True
['DefaultVersion','Default'][1] = None
['DefaultVersion','Current'][0] = None

And so on.

This dict/list is then processed by other existing code, so I don't
want to have to rewrite a ton of code - I just want to fix the list so
the items end up in their correct slots.
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Re: Ifs and assignments

2014-01-03 Thread Duncan Booth

Chris Angelico ros...@gmail.com wrote:

 Maybe a for loop isn't the best other example, but I
 frequently work with places where I want to call some function and
 keep iterating with the result of that until it returns false:
 
 while (var = func())
 {
 
 }
 
 In Python, that gets a lot clunkier. The most popular way is to turn
 it into an infinite loop:
 
 while True:
 var = func()
 if not var: break
 
 

My preferred way would be to write it as a `for` loop:

for var in iter(func, False):
   ...


Though you do have to be sure to get the sentinel value correct as it will 
only break for the expected terminal False, not for 0, , or None.

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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 2:51 AM, Roy Smith r...@panix.com wrote:
 In article mailman.4853.1388763434.18130.python-l...@python.org,
  Chris Angelico ros...@gmail.com wrote:

 Alternatively, if you expect to fill in most of the elements, it's
 possible you'd be happier working with a subclass of list that
 auto-expands by filling in the spare space with a singleton meaning
 no element here.

 And, if you know ahead of time the maximum number of elements you will
 ever have:

 x = [None] * max_count

 will preallocate them all with a minimum of fuss.

Yes, as I use in the trivial example in the subsequent post. But as a
general solution this is usually insufficient. (Whether or not None is
valid as a sentinel is, of course, quite orthogonal to the discussion.
I avoided assuming that it was, the OP's now shown that it does seem
to be.)

ChrisA
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Re: Creating a list with holes

In article mailman.4853.1388763434.18130.python-l...@python.org,
 Chris Angelico ros...@gmail.com wrote:

 Alternatively, if you expect to fill in most of the elements, it's
 possible you'd be happier working with a subclass of list that
 auto-expands by filling in the spare space with a singleton meaning
 no element here.

And, if you know ahead of time the maximum number of elements you will 
ever have:

x = [None] * max_count

will preallocate them all with a minimum of fuss.
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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 2:55 AM, Larry Martell larry.mart...@gmail.com wrote:
 The use case is that I'm parsing a XML file like this:

   Parameter Name=DefaultVersion
 Values
   Value
 DefaultTrue/Default
   /Value
 /Values
 Values
   Value
 CurrentFalse/Current
   /Value
 /Values
 Values
   Value
 DefaultTrue/Default
 CurrentFalse/Current
   /Value
 /Values
 Values
   DefaultTrue/Default
 /Values

 This is an existing program that is putting the data into a dict. The
 dict keys are ['DefaultVersion','Default'] and
 ['DefaultVersion','Current']. These contain lists that have the
 True/False values.

Are you assigning keys by value, or are you simply appending to the
lists? It looks to me like you could simply append another element to
both lists for each Value /Value unit, with the given Default and
Current if available, or with None for any that aren't set.
Alternatively, when you get up to the Value, append None to each
list, and then when you see a value, assign to [-1] and overwrite the
None.

ChrisA
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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Chris Seberino


Exceptions, modules, OOP, etc. would be tricky to implement in Scheme but at 
least the basics like for loops, while loops, assignment etc. would seem doable 
and very instructive for students.they would thereafter, for all time, have 
a mental image of what the Python interpreter is doing.


 But then theres also (apart from parsing) all kinds of semantic differences 
 eg:
 
 - exceptions
 
 - modules
 
 - OOP milarky
 
 - C interfacing in Baskin Robbins number of flavours
 
 - carefully crafted portable veneer on top of intrinsically non portable OSes
 

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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Devin Jeanpierre

On Thu, Jan 2, 2014 at 10:46 PM, Chris Seberino cseber...@gmail.com wrote:
 I've heard it said, by no less a guru than Peter Norvig, that Python is a lot 
 like Lisp without the parentheses at least for the basics of Python.

There are plenty of non-superficial differences. Python has lexical
scope, lisps usually have dynamic scope. Python has statements and
expressions, lisps have expressions and maybe only a few tiny extra
restrictions. Python has dynamic dispatch everywhere, lisps have it
usually almost nowhere. And the unifying thing that makes a lisp a
lisp is macros, which Python lacks.

 For pedagogical reasons, I'm wondering if it would be easy to implement a big 
 subset of Python in Scheme.

A lecturer of mine back in university did this (implemented a subset
of Python in Racket). My understanding is that this is primarily
interesting to show that Racket is not as crazily different as it
looks from the syntax.

When I TA'd for him, he had a really neat lecture where he gave the
following three snippets of code:

// C++
Foo x = y;
x.bar = 3;

// Java
Foo x = y;
x.bar = 3;

// Scheme
(define x y)
(foo-bar x 3)

The syntax of the first two is identical, so the uneducated would
assume they do the same thing. But actually, the latter two are the
ones with the identical behaviour. It is definitely true that the
syntax differences hide how similar Scheme and Python are. These two
languages are close enough together that any

 The basics of Scheme or Lisp are amazingly easy to implement.  Would 
 implementing a subset of Python in a Scheme subset be a clever way to easily 
 implement a lot of Python?

If it's easy to implement in terms of Scheme, which is itself easy to
implement, then it would be easy to implement directly, so this
doesn't seem like a useful question to ask. Anyway, most of the useful
bits of Python aren't present or have different semantics than how
they work in lisps.

-- Devin
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Re: Blog about python 3

2014-01-03 Thread Ethan Furman


On 01/03/2014 02:24 AM, Chris Angelico wrote:


I worked that out with a sheet of paper and a pencil. The pencil was a
little help, but the paper was three sheets in the wind.


Beautiful!

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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Chris Seberino

On Friday, January 3, 2014 11:10:07 AM UTC-6, Devin Jeanpierre wrote:

 A lecturer of mine back in university did this (implemented a subset
 
 of Python in Racket). My understanding is that this is primarily
 
 interesting to show that Racket is not as crazily different as it
 
 looks from the syntax.

Is that on the web anywhere?  That would be very interesting to look at.  I'm 
sure others would find it useful too.
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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

In article mailman.4862.1388769050.18130.python-l...@python.org,
 Devin Jeanpierre jeanpierr...@gmail.com wrote:

 // C++
 Foo x = y;
 x.bar = 3;
 
 // Java
 Foo x = y;
 x.bar = 3;
 
 // Scheme
 (define x y)
 (foo-bar x 3)
 
 The syntax of the first two is identical, so the uneducated would
 assume they do the same thing. 

This is one of the things that tripped me up when I first tried to learn 
JavaScript.  They syntax is superficially identical to C++, so I assumed 
it worked the same way.  Bad assumption.
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Re: Python 2.x and 3.x usage survey

2014-01-03 Thread emile


On 01/02/2014 08:55 AM, Grant Edwards wrote:

On 2013-12-31, Steven D'Aprano steve+comp.lang.pyt...@pearwood.info wrote:



You laugh, but there was at least one attendee at the last PyCon who was
still using 1.5 professionally. Software never quite dies so long as there
is hardware capable of running it.


ITYM: ... so long as there is hardware capable of running an emulator
that is capable of running it.



...or as long as there's business value in keeping it running.  As I 
recall it took the banking industry decades to move things forward.  I 
still maintain software for customers that I originally wrote 35 years 
ago.  Rule one is don't fix it if it ain't broke, so yes, I've got 
python projects deployed that run under everything from 1.5.2 on.


Fortunately, they all work without issue so maintenance isn't a problem.

Emile


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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Rustom Mody

On Fri, Jan 3, 2014 at 10:20 PM, Chris Seberino cseber...@gmail.com wrote:

 Exceptions, modules, OOP, etc. would be tricky to implement in Scheme but at 
 least the basics like for loops, while loops, assignment etc. would seem 
 doable and very instructive for students.they would thereafter, for all 
 time, have a mental image of what the Python interpreter is doing.

If thats the intent, sure, scheme is heaven for such
In particular, take a language, break it up into a dozen or so
'little-languages' eg
one for types, one for control structures, one for scoping/parameter
passing etc while 'stubbing out' the rest -- for such scheme is simply
unbeatable.
And this includes IDEAS of oop modules etc.

Its only when you then start demanding: Why cant this become
realistic? that things start creaking and groaning at the edges

A simple example:
One of the much touted features of modern functional languages like
Haskell (actually its the SML family) is pattern matching. I
implemented a macro -- destruct -- to do it in scheme -- all of 91
lines!

Now one gets greedy and says: Hey! Neat! Only small catch is that
haskell patterns looks so much neater than these home-cooked
Lots-of-Irritating-Single-Parenthesis (aka Lisp-y) patterns. And
Wham! The shit begins to hit the ceiling

To my mind, scheme is so powerful that even Abelson and Sussman dont
get how powerful.  I wrote a blog post on that but then diluted the
title :D
http://blog.languager.org/2013/08/applying-si-on-sicp.html

On the whole though, functional languages are distinctly weaker than
lisps but much easier for students.  Heres an old Wadler paper
explaining that:
http://www.cs.kent.ac.uk/people/staff/dat/miranda/wadler87.pdf
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Re: Creating a list with holes

2014-01-03 Thread Denis McMahon

On Fri, 03 Jan 2014 10:41:21 -0500, Larry Martell wrote:

 The holes would be between the items I put in. In my example above, if I
 assigned to [10] and [20], then the other items ([0..9] and [11..19])
 would have None.

 dic = { 10:6, 20:11}
 dic.get(10)
6
 dic.get(14)
 dic.get(27,oh god there's nothing here)
oh god there's nothing here
 dic.get(99,None)
 dic.get(168,False)
False
 dic.get(20,Boo Yah)
11


So a standard dictionary does this returning None (or any other default 
value you care to pass it) as long as you use the dict.get(key[,default]) 
method rather than dict[key] to return the value.

See also: 

http://stackoverflow.com/questions/6130768/return-none-if-dictionary-key-
is-not-available

-- 
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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Devin Jeanpierre

On Fri, Jan 3, 2014 at 9:26 AM, Chris Seberino cseber...@gmail.com wrote:
On Friday, January 3, 2014 11:10:07 AM UTC-6, Devin Jeanpierre wrote:
A lecturer of mine back in university did this (implemented a subset
of Python in Racket). My understanding is that this is primarily
interesting to show that Racket is not as crazily different as it
looks from the syntax.

Is that on the web anywhere? That would be very interesting to look at. I'm
sure others would find it useful too.

As far as I know, no. There was an early version of it that was part
of a course, but as I understand it he did something much more
thorough later on. Even that course content seems to be offline and
not very available by archive.org; the relevant bits aren't archived:
https://web.archive.org/web/2019221012/http://www.cs.toronto.edu/~gfb/csc324/2010F/content.shtml

Feel free to dig around and try to find something, but as I recall the
assignment on that page was to write some very minor interpreter
actions with a list generated from the AST of a python source file.
His later work was translating Python to Racket, with macros to
implement various Python operations. That wasn't an assignment or
course content, it was stuff he'd show to students during office hours
and such.

I believe the end goal was to turn it into a real tool for teaching
programming. The idea there was that Python is 90% irrelevant to
teaching students how to program, and the full generality of Python
makes it harder for students to learn due to weird behaviours or
unreasonable complexity. If you decide to only implement the 10% of
Python that you care to teach, then it's much easier to implement (in
fact, without that, the goal isn't even achievable for one person),
plus it serves your goals potentially better than Python does.

Regardless of if it's a particularly good idea, this is what Python
must look like if you try to elegantly directly translate it to Scheme
(or any lisp), just because the semantics will be so different once
you get out of the basics and the trivial things. If the translation
is to be clean, the input language can't actually be Python. If the
input language is Python, the output will be a horrible mess that
isn't useful for the student, and also it will take a lot of work
until it is even correct. Scheme is far simpler and smaller than
Python is.

-- Devin
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The Economic System of Islam

2014-01-03 Thread BV BV

The Economic System of Islam

1-An introduction to the principles Islam has legislated to guide the economic 
system of society. Part 1: The sources from which the laws that guide 
economical activity are derived.
2-The Ideological Basis of Economic Activity and the general principles by 
which they are guided
 
Introduction
As a complete way of life, Islam has provided guidelines and rules for every 
sphere of life and society.  Naturally, a functioning economic system is vital 
for a healthy society, as the consumption of goods and services, and the 
facilitation of this by a common medium of exchange, play a major role in 
allowing people to realize their material and other goals in life.

Islam has set some standards, based on justice and practicality, for such 
economic systems to be established.  These standards aim to prevent the enmity 
that often occurs between different socioeconomic sections.  Of course, it is 
true that the gathering of money concerns almost every human being who 
participates in transactions with others.  Yet, while these standards recognize 
money as being among the most important elements in society, they do not lose 
sight of the fact that its position is secondary to the real purpose of human 
existence, which is the worship of God.

An Islamic economic system is not necessarily concerned with the precise amount 
of financial income and expenditure, imports and exports, and other economic 
statistics.  While such matters are no doubt important, Islam is more concerned 
with the spirit of the economic system.

A society that implements Islamic laws and promotes Islamic manners will find 
that it bring together all the systems – social, economic, and so forth – that 
it deals with.  Islam teaches that God has created provision for every person 
who He has brought to life.  Therefore, the competition for natural resources 
that is presumed to exist among the nations of the world is an illusion.  While 
the earth has sufficient bounty to satisfy the needs of mankind, the challenge 
for humans lies in discovering, extracting, processing, and distributing these 
resources to those who need them.

Islam consists of a set of beliefs which organizes the relationship between the 
individual and his Creator; between the person and other human beings; between 
the person and universe; and even the relationship of the person to himself.  
In that sense, Islam regulates human behavior, and one type of human behavior 
is economic behavior.  Economic behavior is dealt by Muslims as a means of 
production, distribution, and consumption of goods and services.  In Islam, 
human behavior -whether in the economic area or others - is not value free; nor 
is it value neutral.  It is connected with the ideological foundation of the 
faith.

The Sources of Islamic Economics
The fundamental sources of Islam - the Quran and the Sunnah of the Prophet[1] - 
provide guidelines for economic behavior and a blueprint of how the economic 
system of a society should be organized.  Therefore, the values and objectives 
of all “Islamic” economic systems must necessarily conform to, and comply with, 
the principles derived from these fundamental sources.  The purpose of these 
articles is to outline the most salient characteristics of an economic system 
based on the fundamental sources of Islam.  The focus here is on the principal 
features of the Islamic system.

The Islamic economic system is defined by a network of rules called the 
Shariah.  The rules which are contained in the Shariah are both constitutive 
and regulative, meaning that they either lay the rules for the creation of 
economic entities and systems, as well the rules which regulate existing one. 
As an integral part of the revelation, the Shariah is the guide for human 
action which encompasses every aspect of life – spiritual, individual, social, 
political, cultural, and economic.  It provides a scale by which all actions, 
whether on the part of the individual agents, society, and the state, are 
classified in regards to their legality.  Thus there are five types of actions 
recognized, namely: obligatory; recommended; permissible; discouraged; and 
forbidden.  This classification is also inclusive of economic behavior.

The basic source of the Shariah in Islam is the Quran and the Sunnah, which 
include all the necessary rules of the Shariah as guidance for mankind.  The 
Sunnah further explains these rules by the practical application of Prophet 
Muhammad, may the mercy and blessings of God be upon him.  The expansion of the 
regulative rules of the Shariah and their extensions to new situations in later 
times was accomplished with the aid of consensus of the scholars, analogical 
reasoning - which derived rules by discerning an analogy between new problems 
and those existing in the primary sources - and finally, through textual 
reasoning of scholars specialized in the Shariah.  These five sources - the 
Quran, the Sunnah, consensus

Re: About some problem

2014-01-03 Thread André Malo

* Steven D'Aprano wrote:

 Mark Lawrence wrote:
 
 raise Not Valid DB Type
 
 is perfectly valid in Python 2.
 
 Actually, no it isn't. It's only valid up to Python 2.4. In Python 2.5,
 string exceptions display a warning but continue to work, and in Python
 2.6 they generate a compile-time SyntaxError.

Oh? Doesn't look like it.

$ cat x.py
try:
raise foo
except:
print bar

$ python2.7 x.py
bar
$ python2.6 x.py
bar

A lone '''raise foo''' raises a TypeError, though.

nd
-- 
sub the($){+shift} sub answer (){ord q
[* It is always 42! *]   }
   print the answer
# André Malo # http://pub.perlig.de/ #
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Re: Is Python really Lisp without parentheses? So would it be easy to implement a lot of Python in Scheme/Lisp?

2014-01-03 Thread Steven D'Aprano

Chris Seberino wrote:

 The basics of Scheme or Lisp are amazingly easy to implement.  Would
 implementing a subset of Python in a Scheme subset be a clever way to
 easily implement a lot of Python?

I don't know how easy it was, but it was done:

http://common-lisp.net/project/clpython/



-- 
Steven

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Python 2.x vs 3.x survey

2014-01-03 Thread Dan Stromberg

The results of the survey are at:

https://wiki.python.org/moin/2.x-vs-3.x-survey
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Re: About some problem

2014-01-03 Thread Steven D'Aprano

André Malo wrote:

 * Steven D'Aprano wrote:
 
 Mark Lawrence wrote:
 
 raise Not Valid DB Type
 
 is perfectly valid in Python 2.
 
 Actually, no it isn't. It's only valid up to Python 2.4. In Python 2.5,
 string exceptions display a warning but continue to work, and in Python
 2.6 they generate a compile-time SyntaxError.
 
 Oh? Doesn't look like it.

Oh, it's a runtime TypeError, not SyntaxError. I learn something new
everyday, thanks for the correction.



-- 
Steven

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Re: Debugging on the Mac question.

PETER,

thanks Peter, I have already found the PDB module and have had a play with it. 
It will do for now.
On 03/01/2014, at 8:08 PM, Paul Rudin paul.nos...@rudin.co.uk wrote:

 Sean Murphy mhysnm1...@gmail.com writes:
 
 
 I am a Vision Impaired programmer on the Mac and Window platforms. I have
 started to learn Python. The biggest road block I have is the ability of
 debugging my simple scripts. The IDLE program does not work with the screen
 readers I use on the Mac or Windows. A screen reader is a program that grabs
 the text on the screen and converts it into speech output, at least this is 
 the
 5 feet explanation.  I cannot see the screen at all.
 
 I have looked at eclipse and it doesn't work with Voice-Over (the screen 
 reader
 on the Mac). I have java issues on my windows machine preventing me running
 this app.
 
 If I use $python -d script.py the debugger doesn't seem to trigger on the 
 mac. 
 
 So how I can perform a debug on a script so I can step through it, set up 
 break
 points, watch variables, etc.
 
 It is really annoying me, since under Perl I just added the -d switch and 
 had a
 full debugger that worked at the console level.
 
 For command line debugging see
 http://docs.python.org/3/library/pdb.html. 
 
 
 More generally you might want to investigate
 http://emacspeak.sourceforge.net/ (disclaimer - I have never used
 this, but from what you say you might find it useful).
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Re: About some problem

2014-01-03 Thread Ethan Furman


On 01/03/2014 12:55 PM, Steven D'Aprano wrote:

André Malo wrote:


* Steven D'Aprano wrote:


Mark Lawrence wrote:


raise Not Valid DB Type

is perfectly valid in Python 2.


Actually, no it isn't. It's only valid up to Python 2.4. In Python 2.5,
string exceptions display a warning but continue to work, and in Python
2.6 they generate a compile-time SyntaxError.


Oh? Doesn't look like it.


Oh, it's a runtime TypeError, not SyntaxError.


The main point being that in 2.6 and 2.7 string exceptions do /not/ work.

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Re: Blog about python 3


On 1/3/2014 7:28 AM, Robin Becker wrote:

On 03/01/2014 09:01, Terry Reedy wrote:

There was more speedup in 3.3.2 and possibly even more in 3.3.3, so OP
should run the latter.


python 3.3.3 is what I use on windows. As for astral / non-bmp etc etc
that's almost irrelevant for the sort of tests we're doing which are
mostly simple english text.


If you do not test the cases where 2.7 is buggy and requires nasty 
workarounds, then I can understand why you do not so much appreciate 3.3 
;-).


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[newbie] Recursive algorithm - review

2014-01-03 Thread Wiktor

Hi,
it's my first post on this newsgroup so welcome everyone. :)

I'm still learning Python (v3.3), and today I had idea to design (my first)
recursive function, that generates board to 'Towers' Puzzle:
http://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/towers.html
(so I could in future write algorithm to solve it ;-))

I'm pretty proud of myself - that it works, and that took me only 4 hours
to debug. ;-)
But on Project Euler site sometimes I'm also proud, that I solved some
problem in 30-line script, and then on forum there's one lined solution...

So maybe You might look at this script, and tell me if this can be more
pythonic. It's nothing urgent. I can wait - it works after all. ;-)


Idea is that function generate() 'finds' one number at a time (well,
besides first row), then checks if there are no repetitions in column
(because in row there cannot be by design - I pop out numbers from shuffled
list [1, 2, 3, ..., size] for every row.)
If no repetition - calls the same function to find next number, and so on.
If there is repetition at some point - recursion jumps back, and try
different number on previous position.



import random


def check(towers, x=None):
if x:
c = x % len(towers)   # check only column with
column = []   # value added on pos. x
for i in range(len(towers)):
column.append(towers[i][c])
column = [x for x in column if x != 0]
# print(column)   # debugging leftovers ;-)
return len(column) == len(set(column))
else:
for c in range(len(towers)):  # 'x' not provided,
column = []   # so check all columns
for i in range(len(towers)):
column.append(towers[i][c])
column = [x for x in column if x != 0]
# print(column)
if len(column) != len(set(column)):
return False
return True


def generate(size=4, towers=None, row=None, x=0):
if not towers: # executed only once.
row = [a for a in range(1, size+1)]# Then I'll pass towers list
random.shuffle(row)# at every recursion
towers = []
   # not so pretty way to generate
for i in range(size):  # matrix filled with 0's
towers.append([])  # I tried: towers = [[0]*size]*size
for j in range(size):  # but this doesn't work. ;-)
towers[i].append(0)# I don't know how to do this with
   # list comprehension (one inside
row_ = row[:]  # other?)
towers[0] = row_# after adding first row, columns will be
row = []# always unique, so I add entire row at once.
x = size - 1# Then I will be adding only one num at time.
# 'x' is pretty much position of last added el.
if not row:
row = [a for a in range(1, size+1)]
random.shuffle(row)

if x + 1  size**2:
repeat = True
attempt = 0
while repeat:
# print(towers, row, x)
x += 1
num = row.pop(0)   # take num from right, and
towers[x // size][x % size] = num  # if doesn't match - put
repeat = not check(towers, x)  # back (append) on left -
   # - to rotate
if repeat:   # I'll repeat 'matching' next
row.append(num)  # number as long as last
x -= 1   # changed column is unique
attempt += 1
 # after some attempts I give
if attempt  len(row) - 1:   # up and jump back from
return False # current recursion
else:
if not generate(size, towers, row, x):
repeat = True
row.append(num)  # after some failed attempts
x -= 1   # on this 'level' I give up
attempt += 1 # again...

if attempt  len(row) - 1:
return False# ...and jump back one
# more time...
return towers


def main():
towers6by6 = generate(6)
# print(check(towers6by6))
print(towers6by6)

if __name__ == __main__: main()



Footnote: English isn't my native language, so forgive me my bad grammar
and/or vocabulary. :-)  

-- 
Best regrds,  Wiktor Matuszewski
'py{}@wu{}em.pl'.format('wkm', 'ka')  # spam trap
-- 
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Re: Creating a list with holes

On Fri, Jan 3, 2014 at 1:07 PM, Denis McMahon denismfmcma...@gmail.com wrote:
 On Fri, 03 Jan 2014 10:41:21 -0500, Larry Martell wrote:

 The holes would be between the items I put in. In my example above, if I
 assigned to [10] and [20], then the other items ([0..9] and [11..19])
 would have None.

 dic = { 10:6, 20:11}
 dic.get(10)
 6
 dic.get(14)
 dic.get(27,oh god there's nothing here)
 oh god there's nothing here
 dic.get(99,None)
 dic.get(168,False)
 False
 dic.get(20,Boo Yah)
 11


 So a standard dictionary does this returning None (or any other default
 value you care to pass it) as long as you use the dict.get(key[,default])
 method rather than dict[key] to return the value.

 See also:

 http://stackoverflow.com/questions/6130768/return-none-if-dictionary-key-
 is-not-available

Thanks, but I know all that about dicts. I need to use a list for
compatibility with existing code.
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Re: Creating a list with holes

On Fri, Jan 3, 2014 at 11:07 AM, Chris Angelico ros...@gmail.com wrote:
 On Sat, Jan 4, 2014 at 2:55 AM, Larry Martell larry.mart...@gmail.com wrote:
 The use case is that I'm parsing a XML file like this:

   Parameter Name=DefaultVersion
 Values
   Value
 DefaultTrue/Default
   /Value
 /Values
 Values
   Value
 CurrentFalse/Current
   /Value
 /Values
 Values
   Value
 DefaultTrue/Default
 CurrentFalse/Current
   /Value
 /Values
 Values
   DefaultTrue/Default
 /Values

 This is an existing program that is putting the data into a dict. The
 dict keys are ['DefaultVersion','Default'] and
 ['DefaultVersion','Current']. These contain lists that have the
 True/False values.

 Are you assigning keys by value, or are you simply appending to the
 lists? It looks to me like you could simply append another element to
 both lists for each Value /Value unit, with the given Default and
 Current if available, or with None for any that aren't set.
 Alternatively, when you get up to the Value, append None to each
 list, and then when you see a value, assign to [-1] and overwrite the
 None.

Your last suggestion is what I ended up doing, but I had to key off
the Values /Values unit - I couldn't use Value because that
isn't present for ones that have no Current - that messed me up for
hours. But it's working now. Thanks all!
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[newbie] Recursive algorithm - review

2014-01-03 Thread Wiktor

Hi,
it's my first post on this newsgroup so welcome everyone. :)

I'm still learning Python (v3.3), and today I had idea to design (my first)
recursive function, that generates (filled out) board to 'Towers' Puzzle:

http://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/towers.html

(so I could in future write algorithm to solve it ;-))


I'm pretty proud of myself - that it works, and that took me only 4 hours
to debug. ;-)
But on Project Euler site sometimes I'm also proud, that I solved some
problem in 30-line script, and then on forum there's one lined solution...

So maybe You might look at this script, and tell me if this can be more
pythonic. It's nothing urgent. I can wait - it works after all. ;-)


Idea is that function generate() 'finds' one number at a time (well,
besides first row), then checks if there are no repetitions in column
(because in row there cannot be by design - I pop out numbers from shuffled
list [1, 2, 3, ..., size] for every row.)
If no repetition - calls the same function to find next number, and so on.
If there is repetition at some point - recursion jumps back, and try
different number on previous position.



import random


def check(towers, x=None):
if x:
c = x % len(towers)   # check only column with
column = []   # value added on pos. x
for i in range(len(towers)):
column.append(towers[i][c])
column = [x for x in column if x != 0]
# print(column)   # debugging leftovers ;-)
return len(column) == len(set(column))
else:
for c in range(len(towers)):  # 'x' not provided,
column = []   # so check all columns
for i in range(len(towers)):
column.append(towers[i][c])
column = [x for x in column if x != 0]
# print(column)
if len(column) != len(set(column)):
return False
return True


def generate(size=4, towers=None, row=None, x=0):
if not towers: # executed only once.
row = [a for a in range(1, size+1)]# Then I'll pass towers list
random.shuffle(row)# at every recursion
towers = []
   # not so pretty way to generate
for i in range(size):  # matrix filled with 0's
towers.append([])  # I tried: towers = [[0]*size]*size
for j in range(size):  # but this doesn't work. ;-)
towers[i].append(0)# I don't know how to do this with
   # list comprehension (one inside
row_ = row[:]  # other?)
towers[0] = row_# after adding first row, columns will be
row = []# always unique, so I add entire row at once.
x = size - 1# Then I will be adding only one num at time.
# 'x' is pretty much position of last added el.
if not row:
row = [a for a in range(1, size+1)]
random.shuffle(row)

if x + 1  size**2:
repeat = True
attempt = 0
while repeat:
# print(towers, row, x)
x += 1
num = row.pop(0)   # take num from right, and
towers[x // size][x % size] = num  # if doesn't match - put
repeat = not check(towers, x)  # back (append) on left -
   # - to rotate
if repeat:   # I'll repeat 'matching' next
row.append(num)  # number as long as last
x -= 1   # changed column is unique
attempt += 1
 # after some attempts I give
if attempt  len(row) - 1:   # up and jump back from
return False # current recursion
else:
if not generate(size, towers, row, x):
repeat = True
row.append(num)  # after some failed attempts
x -= 1   # on this 'level' I give up
attempt += 1 # again...

if attempt  len(row) - 1:
return False# ...and jump back one
# more time...
return towers


def main():
towers6by6 = generate(6)
# print(check(towers6by6))
print(towers6by6)

if __name__ == __main__: main()



Footnote: English isn't my native language, so forgive me my bad grammar
and/or vocabulary. :-)  

-- 
Best regrds,  Wiktor Matuszewski
'py{}@wu{}em.pl'.format('wkm', 'ka')  # spam trap
-- 
https://mail.python.org/mailman/listinfo/python-list

Re: Creating a list with holes

In article mailman.4871.1388794533.18130.python-l...@python.org,
 Larry Martell larry.mart...@gmail.com wrote:

 
 Thanks, but I know all that about dicts. I need to use a list for
 compatibility with existing code.

Generalizing what I think the situation is, A dict is the best data 
structure for the parsing phase, but I need a list later to hand off to 
legacy interfaces.

No problem.  Parse the data using a dict, then convert the dict to a 
list later.  I haven't been following all the details here, but just 
wanted to point out that using different data structures to hold the 
same data at different phases of a program is a perfectly reasonable 
approach.
-- 
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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 11:18 AM, Larry Martell larry.mart...@gmail.com wrote:
 Your last suggestion is what I ended up doing, but I had to key off
 the Values /Values unit - I couldn't use Value because that
 isn't present for ones that have no Current - that messed me up for
 hours. But it's working now. Thanks all!

Sure, you know your data better than I do after a quick glance. Sounds good!

Such a classic problem. I have this data, I need that structure. How
can I turn the one into the other? So many different answers.

ChrisA
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Re: [newbie] Recursive algorithm - review


On 1/3/2014 7:16 PM, Wiktor wrote:

Hi,
it's my first post on this newsgroup so welcome everyone. :)

I'm still learning Python (v3.3), and today I had idea to design (my first)
recursive function, that generates (filled out) board to 'Towers' Puzzle:

http://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/towers.html

(so I could in future write algorithm to solve it ;-))


I'm pretty proud of myself - that it works, and that took me only 4 hours
to debug. ;-)
But on Project Euler site sometimes I'm also proud, that I solved some
problem in 30-line script, and then on forum there's one lined solution...

So maybe You might look at this script, and tell me if this can be more
pythonic. It's nothing urgent. I can wait - it works after all. ;-)


Idea is that function generate() 'finds' one number at a time (well,
besides first row), then checks if there are no repetitions in column
(because in row there cannot be by design - I pop out numbers from shuffled
list [1, 2, 3, ..., size] for every row.)
If no repetition - calls the same function to find next number, and so on.
If there is repetition at some point - recursion jumps back, and try
different number on previous position.



import random


def check(towers, x=None):
 if x:
 c = x % len(towers)   # check only column with
 column = []   # value added on pos. x
 for i in range(len(towers)):
 column.append(towers[i][c])
 column = [x for x in column if x != 0]
 # print(column)   # debugging leftovers ;-)
 return len(column) == len(set(column))
 else:
 for c in range(len(towers)):  # 'x' not provided,
 column = []   # so check all columns
 for i in range(len(towers)):
 column.append(towers[i][c])
 column = [x for x in column if x != 0]
 # print(column)
 if len(column) != len(set(column)):
 return False
 return True


def generate(size=4, towers=None, row=None, x=0):
 if not towers: # executed only once.
 row = [a for a in range(1, size+1)]# Then I'll pass towers list
 random.shuffle(row)# at every recursion



 towers = []
# not so pretty way to generate
 for i in range(size):  # matrix filled with 0's
 towers.append([])  # I tried: towers = [[0]*size]*size
 for j in range(size):  # but this doesn't work. ;-)
 towers[i].append(0)# I don't know how to do this with
# list comprehension (one inside


[0]*size] is fine for one row

towers = [[0]*size] for i in range(size)]

should do what you want for a 2-d array instead of the above.

I cannot look at the rest right now.

--
Terry Jan Reedy

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Re: [newbie] Recursive algorithm - review

On Sat, Jan 4, 2014 at 11:13 AM, Wiktor look@signature.invalid wrote:
 Hi,
 it's my first post on this newsgroup so welcome everyone. :)

Hi! Welcome!

 I'm still learning Python (v3.3), and today I had idea to design (my first)
 recursive function, that generates board to 'Towers' Puzzle:
 http://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/towers.html
 (so I could in future write algorithm to solve it ;-))

Yep, that's the way to do things. When I wrote some code for a sort of
binary sudoku system (they're a lot of fun, btw), I went through
this sequence:

0) Figure out a data structure to hold a board state
1) Write code that will ascertain whether a given board state is valid
2) Write code that will deduce more information from a given board state
3) Write code that will completely solve a board
4) Write code that can solve an empty board, thus generating a puzzle.

 But on Project Euler site sometimes I'm also proud, that I solved some
 problem in 30-line script, and then on forum there's one lined solution...

That's not a problem in itself. In fact, in many situations the
30-liner is better. But mainly, once you get a
working-but-slightly-verbose script, it's fairly straight-forward to
simplify it a little bit at a time.

 def check(towers, x=None):
 column = []   # value added on pos. x
 for i in range(len(towers)):
 column.append(towers[i][c])
 column = [x for x in column if x != 0]

Any time you iterate over range(len(something)), you probably want to
iterate over the thing instead:

for t in towers:
column.append(t[c])

And any time you iterate over something and append to another list,
you probably want a list comprehension:

column = [t[c] for t in towers]

And two comprehensions can usually be combined into one:

column = [t[c] for t in towers if t[c] != 0]

That has a little bit of redundancy in there (mentioning t[c] twice),
but I think it's cleaner than having the separate pass. Finally, since
you're working here with integers, you can drop the != 0 check and
simply test the truthiness of t[c] itself:

column = [t[c] for t in towers if t[c]]

 for c in range(len(towers)):  # 'x' not provided,
 column = []   # so check all columns

I wouldn't normally wrap a comment onto an unrelated line; I'd put the
comment above the loop, since it's too long to be a part of the loop
header itself. It goes as much with the else as with the loop,
anyhow.

This is one case where you probably _do_ want to iterate up to
range(len(towers)), though, which is why I said probably above. :)

 for i in range(len(towers)):
 column.append(towers[i][c])
 column = [x for x in column if x != 0]

This is the same code you had above, so it can benefit from the same
translation. But maybe it'd be even cleaner to simply call yourself?

if not check(towers, i): return False

 # print(column)
 if len(column) != len(set(column)):
 return False
 return True

And in fact, you might want to turn this whole branch into something
that harks to a more functional programming style:

return all((check(towers, i) for i in range(len(towers)))

But that's a stylistic choice.

 def generate(size=4, towers=None, row=None, x=0):
 if not towers: # executed only once.
 row = [a for a in range(1, size+1)]# Then I'll pass towers list

row = list(range(1, size+1))

 random.shuffle(row)# at every recursion

Again, I wouldn't wrap comments onto unrelated lines. You see how
confusing this looks, now that I take this line out of context? Same
will happen if it throws an exception.

 towers = []
# not so pretty way to generate
 for i in range(size):  # matrix filled with 0's
 towers.append([])  # I tried: towers = [[0]*size]*size
 for j in range(size):  # but this doesn't work. ;-)
 towers[i].append(0)# I don't know how to do this with
# list comprehension (one inside
 row_ = row[:]  # other?)
 towers[0] = row_# after adding first row, columns will be
 row = []# always unique, so I add entire row at once.
 x = size - 1# Then I will be adding only one num at time.
 # 'x' is pretty much position of last added el.

When you multiply a list of lists, you get references to the same
list, yes. But you could use multiplication for one level:

towers = [[0]*size for _ in range(size)]

That'll give you independent lists. I'm not wholly sure what the rest
of your code is trying to do here, so I can't comment on it.

 if not row:
 row = [a for a in range(1, size+1)]
 random.shuffle(row)

This is the same

Re: Creating a list with holes

2014-01-03 Thread Denis McMahon

On Fri, 03 Jan 2014 20:18:06 -0500, Roy Smith wrote:

 In article mailman.4871.1388794533.18130.python-l...@python.org,
  Larry Martell larry.mart...@gmail.com wrote:
 
 
 Thanks, but I know all that about dicts. I need to use a list for
 compatibility with existing code.
 
 Generalizing what I think the situation is, A dict is the best data
 structure for the parsing phase, but I need a list later to hand off to
 legacy interfaces.
 
 No problem.  Parse the data using a dict, then convert the dict to a
 list later.  I haven't been following all the details here, but just
 wanted to point out that using different data structures to hold the
 same data at different phases of a program is a perfectly reasonable
 approach.

Indeed, assuming the requirement is to have a list of some length n units 
representing integer keys into a range of values from start to end, and 
he creates a dict initially:

list = [ dict.get(x,None) for x in range(start,end + 1) ]

Examples:

 dic = {1:fred, 9:jim, 15:susan, 25:albert }
 l = [ dic.get(x,None) for x in range(1,20) ]
 l
['fred', None, None, None, None, None, None, None, 'jim', None, None, 
None, None, None, 'susan', None, None, None, None]
 l = [ dic.get(x,None) for x in range(-10,50) ]
 l
[None, None, None, None, None, None, None, None, None, None, None, 'fred', 
None, None, None, None, None, None, None, 'jim', None, None, None, None, 
None, 'susan', None, None, None, None, None, None, None, None, None, 
'albert', None, None, None, None, None, None, None, None, None, None, 
None, None, None, None, None, None, None, None, None, None, None, None, 
None, None]
 len(l)
60

then the value of l[offset] will either be None or some string depending 
on the offset into the list

-- 
Denis McMahon, denismfmcma...@gmail.com
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How to make a tkinter GUI work on top of a CUI program?

2014-01-03 Thread Beinan Li

I know how to make a GUI program work on top of a console program like
ls, which exits immediately.

But some console programs have their own shell or ncurse-like CUI, such as
cscope.
So I figured that I need to first subprocess.popen a bidirectional pipe and
send command through stdin and get results from stdout and stderr.

But in such a case I found that communicate('cmd') will freeze.

Am I in the right direction?

Here is my code, in which the application connects to cscope through pipe,
the GUI has only one button that tries to invoke a cscope search command
and get the result, the Enter key is represented as \n in the stdin
argument of communicate():

import sys, os, os.path, subprocess, shlex
if sys.version_info.major  3:
import Tkinter as Tk
else:
import tkinter as Tk
class MyGUI(object):
'''
Frontend of the main command-line module.
'''
def __init__(self):
self.subProc = None
 self.root = Tk.Tk()
self.frame = Tk.Frame(self.root)
 self.btn = Tk.Button(self.frame, text='My Command')
self.btn.pack()
self.btn.bind('Button-1', self.OnClickBtn)
 def MainLoop(self):
os.chdir('path/to/myfolder')
cmd = shlex.split('/usr/local/bin/cscope -d')
self.subProc = subprocess.Popen(cmd, shell=False, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, bufsize=0)
self.root.mainloop()
 def OnClickBtn(self, event):
print('OnClickBtn')
(stdOut, stdErr) = self.subProc.communicate('symbolName\n')
print(stdOut)
if __name__ == '__main__':
gui = MyGUI()
gui.MainLoop()
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Re: How to make a tkinter GUI work on top of a CUI program?

On Sat, Jan 4, 2014 at 1:44 PM, Beinan Li li.bei...@gmail.com wrote:
 But some console programs have their own shell or ncurse-like CUI, such as
 cscope.
 So I figured that I need to first subprocess.popen a bidirectional pipe and
 send command through stdin and get results from stdout and stderr.

 But in such a case I found that communicate('cmd') will freeze.

You can't use communicate(), as it'll wait for the process to end. But
there are several quite different types of console UI, some of which
you'll be able to use and some you won't:

1) There's the simple, straight-forward writing to stdout/stderr.
Maybe it's a long-running 'make' or the burning of a DVD, but whatever
it does, it takes no input and writes to the standard streams. Easy to
work with - just read and handle incoming text.

2) There are interactive shell-type systems. You'll need to send them
more than just lines of text, probably, as you might need to send
command keys and such. But still fairly workable.

3) Then there's stuff that doesn't actually use the standard streams
at all, or uses them and uses something else as well. You can pipe
something into 'less', but it'll still look for actual keyboard input
for its control. You'll have a lot more trouble manipulating those
programs.

Something that uses ncurses is most likely to land in box 3.

ChrisA
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Re: Creating a list with holes

2014-01-03 Thread Dan Stromberg

On Fri, Jan 3, 2014 at 7:37 AM, Chris Angelico ros...@gmail.com wrote:
 Depending on what exactly you need, it's probably worth just using a
 dict. In what ways do you need it to function as a list? You can
 always iterate over sorted(some_dict.keys()) if you need to run
 through them in order.

FWIW, sorting inside a loop is rarely a good idea, unless your lists
are pretty small.

For that, there are many tree datastructures available.
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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 1:58 PM, Dan Stromberg drsali...@gmail.com wrote:
 On Fri, Jan 3, 2014 at 7:37 AM, Chris Angelico ros...@gmail.com wrote:
 Depending on what exactly you need, it's probably worth just using a
 dict. In what ways do you need it to function as a list? You can
 always iterate over sorted(some_dict.keys()) if you need to run
 through them in order.

 FWIW, sorting inside a loop is rarely a good idea, unless your lists
 are pretty small.

What do you mean by sorting inside a loop? I was thinking of this:

for key in sorted(some_dict.keys()):
# blah blah

which will sort once and then iterate over it.

ChrisA
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Re: Creating a list with holes

2014-01-03 Thread Dan Stromberg

On Fri, Jan 3, 2014 at 7:00 PM, Chris Angelico ros...@gmail.com wrote:
 On Sat, Jan 4, 2014 at 1:58 PM, Dan Stromberg drsali...@gmail.com wrote:
 On Fri, Jan 3, 2014 at 7:37 AM, Chris Angelico ros...@gmail.com wrote:
 Depending on what exactly you need, it's probably worth just using a
 dict. In what ways do you need it to function as a list? You can
 always iterate over sorted(some_dict.keys()) if you need to run
 through them in order.

 FWIW, sorting inside a loop is rarely a good idea, unless your lists
 are pretty small.

 What do you mean by sorting inside a loop? I was thinking of this:

 for key in sorted(some_dict.keys()):
 # blah blah

 which will sort once and then iterate over it.

That is fine, sorting once at then end of a script is a good use of
sorted(some_dict.keys()).  However, it probably should be pointed out
that this, while similar, is not so good:

for thing in range(n):
   for key in sorted(some_dict.keys()):
  do_something(thing, key)

...because it's sorting n times.
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Re: Creating a list with holes

On Sat, Jan 4, 2014 at 2:32 PM, Dan Stromberg drsali...@gmail.com wrote:
 That is fine, sorting once at then end of a script is a good use of
 sorted(some_dict.keys()).  However, it probably should be pointed out
 that this, while similar, is not so good:

 for thing in range(n):
for key in sorted(some_dict.keys()):
   do_something(thing, key)

 ...because it's sorting n times.

Oh! Yeah. Yeah, that would be inefficient.

ChrisA
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Re: Blog about python 3

2014-01-03 Thread Mark Lawrence


On 03/01/2014 22:00, Terry Reedy wrote:

On 1/3/2014 7:28 AM, Robin Becker wrote:

On 03/01/2014 09:01, Terry Reedy wrote:

There was more speedup in 3.3.2 and possibly even more in 3.3.3, so OP
should run the latter.


python 3.3.3 is what I use on windows. As for astral / non-bmp etc etc
that's almost irrelevant for the sort of tests we're doing which are
mostly simple english text.


If you do not test the cases where 2.7 is buggy and requires nasty
workarounds, then I can understand why you do not so much appreciate 3.3
;-).



Are you crazy?  Surely everybody prefers fast but incorrect code in 
preference to something that is correct but slow? Except that Python 
3.3.3 is often faster.  And always (to my knowledge) correct.  Upper 
Class Twit of the Year anybody? :)


--
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.


Mark Lawrence

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Re: Suggest an open-source log analyser?

2014-01-03 Thread Alec Taylor

Web interface (and/or SQL-like query interface); is useful for
drilling down and rolling up multiparametric analyses.

Currently looking at logstash, kibana, graylog2 and a few others.
Might end up writing my own to escape the Java dependency.

Would welcome further suggestions.

On Fri, Jan 3, 2014 at 1:13 AM, William Ray Wing w...@mac.com wrote:
 On Jan 2, 2014, at 12:40 AM, Alec Taylor alec.tayl...@gmail.com wrote:

 I use the Python logger class; with the example syntax of:
Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')

 Can of course easily use e.g.: a JSON syntax here instead.

 Are there any open-source log viewers (e.g.: with a web-interface)
 that you'd recommend; for drilling down into my logs?

 Thanks for your suggestions,

 Alec Taylor
 --
 https://mail.python.org/mailman/listinfo/python-list

 Why web interface?  That's a ton of overhead just to look at a text file.
 If you are on UNIX or Linux, I'd just use my favorite editor (or possibly 
 View, which is vi in read-only mode, or More or Less).
 If you give them the extension .log you can use whatever app you use to look 
 at console logs.

 -Bill
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Highest performance HTTP REST microframework?

2014-01-03 Thread Alec Taylor

What is the highest performance REST microframework?

Happy if it's mostly written in C or C++; as long as it provides a
simple routes interface in Python.

Currently using bottle and utilising its application, @route and
app.merge(app2) extra features.
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Strange behaviour with a for loop.

Hello all.

This is a newly question. But I wish to understand why the below code is 
providing different results.

import os, sys


if len(sys.argv)  2:
  filenames = sys.argv[1:]
else
  print (no parameters provided\n)
  sys.edit()

for filename in filenames:
  print (filename is: %s\n %filename)

The above code will return results like:

filename is test.txt

If I modify the above script slightly as shown below, I get a completely 
different result. 

if len(sys.argv)  2:
  filenames = sys.argv[1]
else
  print (no parameters provided\n)
  sys.exit()

for filename in filenames:
  print (filename is:  %s\n % filename)

The result is the filename is spelled out a character at a time. The bit I am 
missing is something to do with splicing or referencing in Python.

Why am I getting different results? In other languages I would have got the 
whole content of the element when using the index of the array (list).


Sean 
filename is: t
filename 

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Re: Strange behaviour with a for loop.

On Fri, Jan 3, 2014 at 11:03 PM, Sean Murphy mhysnq1...@icloud.com wrote:
 Hello all.

 This is a newly question. But I wish to understand why the below code is 
 providing different results.

 import os, sys


 if len(sys.argv)  2:
   filenames = sys.argv[1:]
 else
   print (no parameters provided\n)
   sys.edit()

 for filename in filenames:
   print (filename is: %s\n %filename)

 The above code will return results like:

 filename is test.txt

 If I modify the above script slightly as shown below, I get a completely 
 different result.

 if len(sys.argv)  2:
   filenames = sys.argv[1]
 else
   print (no parameters provided\n)
   sys.exit()

 for filename in filenames:
   print (filename is:  %s\n % filename)

 The result is the filename is spelled out a character at a time. The bit I am 
 missing is something to do with splicing or referencing in Python.

 Why am I getting different results? In other languages I would have got the 
 whole content of the element when using the index of the array (list).


 Sean
 filename is: t
 filename

argv[1] gives just the second item in the list
argv[1:] gives a list containing the items in the list, from the
second to the end

 x = ['foo', 'bar', 'baz']
 print x[1]
bar
 print x[1:]
['bar', 'baz']
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Re: Strange behaviour with a for loop.

On Sat, Jan 4, 2014 at 3:03 PM, Sean Murphy mhysnq1...@icloud.com wrote:
   filenames = sys.argv[1:]

 for filename in filenames:
   print (filename is: %s\n %filename)

versus

   filenames = sys.argv[1]

 for filename in filenames:
   print (filename is:  %s\n % filename)

The first one is slicing sys.argv, so it returns another list. For
instance, sys.argv might be:

['foo.py', 'test', 'zxcv']

in which case sys.argv[1:] would be:

['test', 'zxcv']

which is still a list. But sys.argv[1] is a single string:

'test'

Now, when you use that in a for loop, you iterate over it. Iterating
over a list yields its items, as you'd expect. Iterating over a string
yields its characters. That's why you see it spelled out. Instead of
iterating over a list of file names, you're iterating over a single
file name, which isn't (in this case) all that useful.

Does that explain what you're seeing?

ChrisA
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Re: Highest performance HTTP REST microframework?

On Sat, Jan 4, 2014 at 3:26 PM, Alec Taylor alec.tayl...@gmail.com wrote:
 What is the highest performance REST microframework?

 Happy if it's mostly written in C or C++; as long as it provides a
 simple routes interface in Python.

 Currently using bottle and utilising its application, @route and
 app.merge(app2) extra features.

What do you mean by performance? Most of the time is going to be spent
waiting for the network. Are you looking for maximum concurrent
requests handled? Minimum latency/overhead? Something else?

ChrisA
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Re: Strange behaviour with a for loop.

2014-01-03 Thread Mark Lawrence


On 04/01/2014 04:03, Sean Murphy wrote:

Hello all.

This is a newly question. But I wish to understand why the below code is 
providing different results.

import os, sys


if len(sys.argv)  2:
   filenames = sys.argv[1:]
else
   print (no parameters provided\n)
   sys.edit()

for filename in filenames:
   print (filename is: %s\n %filename)

The above code will return results like:

filename is test.txt

If I modify the above script slightly as shown below, I get a completely 
different result.

if len(sys.argv)  2:
   filenames = sys.argv[1]
else
   print (no parameters provided\n)
   sys.exit()

for filename in filenames:
   print (filename is:  %s\n % filename)

The result is the filename is spelled out a character at a time. The bit I am 
missing is something to do with splicing or referencing in Python.

Why am I getting different results? In other languages I would have got the 
whole content of the element when using the index of the array (list).


Sean
filename is: t
filename



As you've already had answers I'd like to point out that your test for 
len(sys.argv) is wrong, else is missing a colon and sys.edit() is very 
unlikely to work :)


--
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.


Mark Lawrence

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Re: How to make a tkinter GUI work on top of a CUI program?

2014-01-03 Thread Jerry Hill

On Fri, Jan 3, 2014 at 9:44 PM, Beinan Li li.bei...@gmail.com wrote:
 But some console programs have their own shell or ncurse-like CUI, such as
 cscope.
 So I figured that I need to first subprocess.popen a bidirectional pipe and
 send command through stdin and get results from stdout and stderr.

 But in such a case I found that communicate('cmd') will freeze.

Right.  communicate() waits for the subprocess to end, and the
subprocess is still waiting for you to do something.  Instead, you'll
need to read() and write() to the subprocess' stdin and stdout
attributes, probably something like this (untested):

def OnClickBtn(self, event):
print('OnClickBtn')
self.subProc.stdin.write('symbolName\n')
print(self.subProc.stdout.read())

It looks like cscope has both a screen-oriented mode and a line-based
mode.  When you're working with a subprocess like this, you're going
to want to be in the line-based mode, so you'll probably want to add
-l or -L to your command line.

-- 
Jerry
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Re: Suggest an open-source log analyser?

2014-01-03 Thread Walter Hurry

On Thu, 02 Jan 2014 16:40:19 +1100, Alec Taylor wrote:

 I use the Python logger class; with the example syntax of:
 Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
 
 Can of course easily use e.g.: a JSON syntax here instead.
 
 Are there any open-source log viewers (e.g.: with a web-interface)
 that you'd recommend; for drilling down into my logs?
 
If you want to do in-depth analysis, why not just stick it into an SQL 
database; e.g. SQLite or Postgres?

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Re: Creating a list with holes

2014-01-03 Thread Frank Millman


Larry Martell larry.mart...@gmail.com wrote in message 
news:CACwCsY5P47-dB1NLQTUTQ=0aF6B+-M3y4hCxcUGmcVmHM8=-x...@mail.gmail.com...
I think I know the answer is no, but is there any package that allows
 creating a list with holes in it? E.g. I'd want to do something like:

 x[10] = 12
 x[20] = 30

 I'm thinking of something like defaultdict but for lists (I know
 that's very different, but ... )

 Thanks!
 -larry

Just out of interest, I asked the same question on this list many years ago, 
and someone actually gave me an answer. It was something like the 
following -

 class MyList(list):
... def __getitem__(self, pos):
... try:
... return list.__getitem__(self, pos)
... except IndexError:
... return None
... def __setitem__(self, pos, value):
... try:
... list.__setitem__(self, pos, value)
... except IndexError:
... diff = pos - list.__len__(self)
... self.extend([None] * diff)
... self.append(value)
...
 ml = MyList()
 ml[3]
 ml[3] = 'a'
 ml
[None, None, None, 'a']


I wanted it because I was familiar with it from a previous language I had 
used. As is turns out, I never actually used it, but I was impressed!

Frank Millman



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Re: Blog about python 3

2014-01-03 Thread Mark Lawrence


On 02/01/2014 17:36, Robin Becker wrote:

On 31/12/2013 15:41, Roy Smith wrote:

I'm using 2.7 in production.  I realize that at some point we'll need to
upgrade to 3.x.  We'll keep putting that off as long as the effort +
dependencies + risk metric exceeds the perceived added value metric.


We too are using python 2.4 - 2.7 in production. Different clients
migrate at different speeds.



To be honest, the perceived added value in 3.x is pretty low for us.
What we're running now works.  Switching to 3.x isn't going to increase
our monthly average users, or our retention rate, or decrease our COGS,
or increase our revenue.  There's no killer features we need.  In
summary, the decision to migrate will be driven more by risk aversion,
when the risk of staying on an obsolete, unsupported platform, exceeds
the risk of moving to a new one.  Or, there will be some third-party
module that we must have which is no longer supported on 2.x.



+1


If I were starting a new project today, I would probably start it in 3.x.

+1

I just spent a large amount of effort porting reportlab to a version
which works with both python2.7 and python3.3. I have a large number of
functions etc which handle the conversions that differ between the two
pythons.

For fairly sensible reasons we changed the internal default to use
unicode rather than bytes. After doing all that and making the tests
compatible etc etc I have a version which runs in both and passes all
its tests. However, for whatever reason the python 3.3 version runs slower

2.7 Ran 223 tests in 66.578s

3.3 Ran 223 tests in 75.703s

I know some of these tests are fairly variable, but even for simple
things like paragraph parsing 3.3 seems to be slower. Since both use
unicode internally it can't be that can it, or is python 2.7's unicode
faster?

So far the superiority of 3.3 escapes me, but I'm tasked with enjoying
this process so I'm sure there must be some new 'feature' that will
help. Perhaps 'yield from' or 'raise from None' or ...

In any case I think we will be maintaining python 2.x code for at least
another 5 years; the version gap is then a real hindrance.


Of interest 
https://mail.python.org/pipermail/python-dev/2012-October/121919.html ?


--
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.


Mark Lawrence

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Re: Strange behaviour with a for loop.

Thanks everyone.

Mark thanks for the correction on the ':'. Since I didn't cut and copy, rather 
typed it out. Errors crept in. :-)

another question in relation to slicing strings. If you want to get a single 
character, just using the index position will get it. If I use the following, 
shouldn't it also work? when I use Python 3.3, it didn't provide anything.

a = test.txt
print a[3]

result is:

't


print a[3:1]

Nothing is printed. 

print a[3:2]


Nothing is printed.

print a[3:-1]

t.tx is printed.


Why doesn't the positive number of characters to be splice return anything 
while the negative value does?

sorry about these basic questions. I do like the splice feature within Python. 
Also what is the best method of testing for a blank string?

end of paragraph line 1 


new paragraph of line 1.


The above example text is what I want to test for. I am planning to either load 
the whole file in as a single chunk of memory using fp.read() or store it into 
an array by using fp.readlines(). The first option I see being useful because 
you can create a regular expression to test for multiple '\n'. While in an 
array (list) I would have to test for a blank line which I assume would be .

Any suggestions on this would be welcomed.

Sean 



print a[

On 04/01/2014, at 4:38 PM, Mark Lawrence breamore...@yahoo.co.uk wrote:

 On 04/01/2014 04:03, Sean Murphy wrote:
 Hello all.
 
 This is a newly question. But I wish to understand why the below code is 
 providing different results.
 
 import os, sys
 
 
 if len(sys.argv)  2:
   filenames = sys.argv[1:]
 else
   print (no parameters provided\n)
   sys.edit()
 
 for filename in filenames:
   print (filename is: %s\n %filename)
 
 The above code will return results like:
 
 filename is test.txt
 
 If I modify the above script slightly as shown below, I get a completely 
 different result.
 
 if len(sys.argv)  2:
   filenames = sys.argv[1]
 else
   print (no parameters provided\n)
   sys.exit()
 
 for filename in filenames:
   print (filename is:  %s\n % filename)
 
 The result is the filename is spelled out a character at a time. The bit I 
 am missing is something to do with splicing or referencing in Python.
 
 Why am I getting different results? In other languages I would have got the 
 whole content of the element when using the index of the array (list).
 
 
 Sean
 filename is: t
 filename
 
 
 As you've already had answers I'd like to point out that your test for 
 len(sys.argv) is wrong, else is missing a colon and sys.edit() is very 
 unlikely to work :)
 
 -- 
 My fellow Pythonistas, ask not what our language can do for you, ask what you 
 can do for our language.
 
 Mark Lawrence
 
 -- 
 https://mail.python.org/mailman/listinfo/python-list

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Re: Strange behaviour with a for loop.

Hi everyone.

Worked out what I was doing wrong with the string splicing. The offset number 
was lower then the index number, so it was failing. E.G:




On 04/01/2014, at 4:54 PM, Sean Murphy mhysnm1...@gmail.com wrote:

 Thanks everyone.
 
 Mark thanks for the correction on the ':'. Since I didn't cut and copy, 
 rather typed it out. Errors crept in. :-)
 
 another question in relation to slicing strings. If you want to get a single 
 character, just using the index position will get it. If I use the following, 
 shouldn't it also work? when I use Python 3.3, it didn't provide anything.
 
 a = test.txt
 print a[3]
 
print a[4:1] --- index is 4 and offset is one. This is invalid.

So I suspect the offset number still starts at the beginning of the string and 
counts forward or another way to look at it you are slicing from element x to 
element y. If element y is less then element x, return nothing. Does this make 
sense?

I should have used:

print a[4:6])

to get:

t.t 

The 2nd part of my original question still stands. I will expand upon this a 
bit more to give more context. I want to print from the beginning of the 
paragraph to the end. Each paragraph ends with \n\n\n. 

If I use \n\n\n in lines this does return true for the string. But I don't 
have a starting position and ending position. The list method which I mention 
before can be sliced by going back one element.

Any suggestion on this would be welcomed. I want to achieve this using standard 
core python objects/methods.

Sean 
 result is:
 
 't
 
 
 print a[3:1]
 
 Nothing is printed. 
 
 print a[3:2]
 
 
 Nothing is printed.
 
 print a[3:-1]
 
 t.tx is printed.
 
 
 Why doesn't the positive number of characters to be splice return anything 
 while the negative value does?
 
 sorry about these basic questions. I do like the splice feature within 
 Python. Also what is the best method of testing for a blank string?
 
 end of paragraph line 1 
 
 
 new paragraph of line 1.
 
 
 The above example text is what I want to test for. I am planning to either 
 load the whole file in as a single chunk of memory using fp.read() or store 
 it into an array by using fp.readlines(). The first option I see being useful 
 because you can create a regular expression to test for multiple '\n'. While 
 in an array (list) I would have to test for a blank line which I assume would 
 be .
 
 Any suggestions on this would be welcomed.
 
 Sean 
 
 
 
 print a[
 
 On 04/01/2014, at 4:38 PM, Mark Lawrence breamore...@yahoo.co.uk wrote:
 
 On 04/01/2014 04:03, Sean Murphy wrote:
 Hello all.
 
 This is a newly question. But I wish to understand why the below code is 
 providing different results.
 
 import os, sys
 
 
 if len(sys.argv)  2:
  filenames = sys.argv[1:]
 else
  print (no parameters provided\n)
  sys.edit()
 
 for filename in filenames:
  print (filename is: %s\n %filename)
 
 The above code will return results like:
 
 filename is test.txt
 
 If I modify the above script slightly as shown below, I get a completely 
 different result.
 
 if len(sys.argv)  2:
  filenames = sys.argv[1]
 else
  print (no parameters provided\n)
  sys.exit()
 
 for filename in filenames:
  print (filename is:  %s\n % filename)
 
 The result is the filename is spelled out a character at a time. The bit I 
 am missing is something to do with splicing or referencing in Python.
 
 Why am I getting different results? In other languages I would have got the 
 whole content of the element when using the index of the array (list).
 
 
 Sean
 filename is: t
 filename
 
 
 As you've already had answers I'd like to point out that your test for 
 len(sys.argv) is wrong, else is missing a colon and sys.edit() is very 
 unlikely to work :)
 
 -- 
 My fellow Pythonistas, ask not what our language can do for you, ask what 
 you can do for our language.
 
 Mark Lawrence
 
 -- 
 https://mail.python.org/mailman/listinfo/python-list
 

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Re: Strange behaviour with a for loop.

On Sat, Jan 4, 2014 at 5:32 PM, Sean Murphy mhysnm1...@gmail.com wrote:
 So I suspect the offset number still starts at the beginning of the string 
 and counts forward or another way to look at it you are slicing from element 
 x to element y. If element y is less then element x, return nothing. Does 
 this make sense?

 I should have used:

 print a[4:6])

 to get:

 t.t

Yep, it's start and end indices, not start and length. When you use a
negative number, it counts from the back:

 asdf[-1]
'f'
 asdf[-2]
'd'

 The 2nd part of my original question still stands. I will expand upon this a 
 bit more to give more context. I want to print from the beginning of the 
 paragraph to the end. Each paragraph ends with \n\n\n.

 If I use \n\n\n in lines this does return true for the string. But I don't 
 have a starting position and ending position. The list method which I mention 
 before can be sliced by going back one element.

The in operator just tells you whether it's there or not; strings
have a .index() method that tells you where something can be found.
That might be what you want here!

ChrisA
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Re: Strange behaviour with a for loop.

2014-01-03 Thread Cameron Simpson

On 04Jan2014 16:54, Sean Murphy mhysnm1...@gmail.com wrote:
 Thanks everyone.
 
 Mark thanks for the correction on the ':'. Since I didn't cut and copy, 
 rather typed it out. Errors crept in. :-)
 
 another question in relation to slicing strings. If you want to get a single 
 character, just using the index position will get it. If I use the following, 
 shouldn't it also work? when I use Python 3.3, it didn't provide anything.
 
 a = test.txt
 print a[3]
 result is:
 
 't

As expected, yes?

 print a[3:1]
 Nothing is printed. 
 
 print a[3:2]
 Nothing is printed.

These are not requests for 1 and 2 character strings. They are
requests for the character in the span from, respectively, 3 to 1
and from 3 to 2. Important: counting FORWARDS. So: zero length
strings.

 print a[3:-1]
 t.tx is printed.
 
 Why doesn't the positive number of characters to be splice return anything 
 while the negative value does?

-1 is shorthand for len(a)-1
It is often convenient to refer to a position from the end of the
array instead of the start.

So this means: [3:7], so positions 3,4,5,6.

 sorry about these basic questions. I do like the splice feature within 
 Python. Also what is the best method of testing for a blank string?

Well, and empty string: a == '' or len(a) == 0.
And, because an if tests the nonzeroness of a single argument and
an empty string has length zero, you can also go:

  if a:
print long string, a
  else:
print empty string

OTOH, if you mean a blank string to mean containing only
whitespace, you can use the string method isspace, which tests
that all characters are whitespace and that the string is not empty.
The doco for isspace() actually says:

  Return true if there are only whitespace characters in the string
  and there is at least one character, false otherwise.

So you might write:

  if not a or a.isspace():
print blank string:, repr(a)

Really you'd want to put that it a (trivial) function:

  def isblank(s):
''' Test that the string `s` is entirely blank.
'''
return not s or s.isspace()

That way you can write isblank() all through your program and control the
precise meaning by modifying the function.

Cheers,
-- 

The perl5 internals are a complete mess. It's like Jenga - to get the perl5
tower taller and do something new you select a block somewhere in the middle,
with trepidation pull it out slowly, and then carefully balance it somewhere
new, hoping the whole edifice won't collapse as a result.
- Nicholas Clark, restating an insight of Simon Cozens
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[issue19944] Make importlib.find_spec load packages as needed


Eric Snow added the comment:

find_spec() is at package level because find_module() is and for no other good 
reason I'm aware of.  I'd be just fine with moving it to util.  I don't expect 
it to be used enough to warrant that top-level placement.

Regarding builtins.__import__(), I'm using it in the event that someone 
installed their own __import__() which gives a different result than 
import_module().  Thus the parent used by find_spec() will be the expected one. 
 I agree that comment about this would be good.

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[issue19713] Deprecate various things in importlib thanks to PEP 451


Eric Snow added the comment:

Here's a patch that updates a couple files to not use find_module/load_module.  
These are the only changes like this (of consequence) outside pydoc, pkgutil, 
and importlib, which are covered by other tickets.

--
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[issue19708] Check pkgutil for anything missing for PEP 451


New submission from Eric Snow:

Here's a patch that does the minimum of updating pkgutil and its tests to move 
away from find_module/load_module.  I'm not sure there is much more to do than 
this.

--
keywords: +patch
Added file: http://bugs.python.org/file33301/issue19708-use-new-api.diff

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[issue19703] Update pydoc to PEP 451


Eric Snow added the comment:

Here's a patch that updates pydoc to move away from find_module/load_module.

These 4 don't need to change for PEP 451:

safeimport()
HTMLDoc.docmodule()
HTMLDoc.index()
TextDoc.docmodule()

--
keywords: +patch
Added file: http://bugs.python.org/file33302/issue19703-use-new-api.diff

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[issue19699] Update zipimport for PEP 451


Eric Snow added the comment:

Could this wait for 3.5?

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[issue16039] imaplib: unlimited readline() from connection


STINNER Victor added the comment:

Why is this issue still open? The issue was fixed in Python 2.6.9. Why is the 
issue a release blocker? The issue was also fixed in the future Python 3.4 (in 
default).

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[issue19699] Update zipimport for PEP 451

2014-01-03 Thread Nick Coghlan


Nick Coghlan added the comment:

I don't see any problem with postponing the zipimport updates until 3.5 (we 
won't be updating the extension module handling until then anyway, since that 
requires C API additions).

--

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[issue20113] os.readv() and os.writev() don't raise an OSError on readv()/writev() failure


New submission from STINNER Victor:

Example:

$ python3
Python 3.3.2 (default, Nov  8 2013, 13:38:57) 
[GCC 4.8.2 20131017 (Red Hat 4.8.2-1)] on linux
Type help, copyright, credits or license for more information.
 import os
 os.fstat(19)
Traceback (most recent call last):
  File stdin, line 1, in module
OSError: [Errno 9] Bad file descriptor
 buf=bytearray(10)
 os.readv(19, [buf])
-1

I would expect an OSError on os.readv() instead of -1.

Moreover, empty list of buffers are not handled correctly:

$ python3
Python 3.3.2 (default, Nov  8 2013, 13:38:57) 
[GCC 4.8.2 20131017 (Red Hat 4.8.2-1)] on linux
Type help, copyright, credits or license for more information.
 import os
 os.readv(0, [])
Traceback (most recent call last):
  File stdin, line 1, in module
SystemError: error return without exception set

Attached patch should fix both issues.

--
messages: 207220
nosy: haypo
priority: normal
severity: normal
status: open
title: os.readv() and os.writev() don't raise an OSError on readv()/writev() 
failure
versions: Python 3.3, Python 3.4

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[issue20113] os.readv() and os.writev() don't raise an OSError on readv()/writev() failure


STINNER Victor added the comment:

os.readv() and os.writev() were added in Python 3.3 with the issue #10812.

--
keywords: +patch
nosy: +serhiy.storchaka
Added file: http://bugs.python.org/file33303/readv_writev.patch

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[issue18294] zlib module is not completly 64-bit safe

2014-01-03 Thread Roundup Robot


Roundup Robot added the comment:

New changeset 0cca6c5513d2 by Victor Stinner in branch 'default':
Issue #18294: Fix uint_converter() in zlibmodule.c, fix the  UINT_MAX check
http://hg.python.org/cpython/rev/0cca6c5513d2

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[issue20114] Sporadic failure of test_semaphore_tracker() of test_multiprocessing_forkserver on FreeBSD 9 buildbot


New submission from STINNER Victor:

http://buildbot.python.org/all/builders/AMD64%20FreeBSD%209.0%203.x/builds/6085/steps/test/logs/stdio

==
FAIL: test_semaphore_tracker 
(test.test_multiprocessing_forkserver.TestSemaphoreTracker)
--
Traceback (most recent call last):
  File 
/usr/home/buildbot/buildarea/3.x.krah-freebsd/build/Lib/test/_test_multiprocessing.py,
 line 3661, in test_semaphore_tracker
_multiprocessing.sem_unlink(name2)
AssertionError: OSError not raised

--
keywords: buildbot
messages: 207223
nosy: haypo, sbt
priority: normal
severity: normal
status: open
title: Sporadic failure of test_semaphore_tracker() of 
test_multiprocessing_forkserver on FreeBSD 9 buildbot
versions: Python 3.4

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[issue16039] imaplib: unlimited readline() from connection

2014-01-03 Thread R. David Murray


R. David Murray added the comment:

Presumably because it has not been fixed in 2.7.

--
nosy: +r.david.murray

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[issue16113] SHA-3 (Keccak) support may need to be removed before 3.4

2014-01-03 Thread Roundup Robot


Roundup Robot added the comment:

New changeset 52350d325b41 by Martin v. Löwis in branch 'default':
* Issue #16113: Remove sha3 module again.
http://hg.python.org/cpython/rev/52350d325b41

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[issue16113] SHA-3 (Keccak) support may need to be removed before 3.4

2014-01-03 Thread Martin v . Löwis


Martin v. Löwis added the comment:

I have now removed the aha code.

--
resolution:  - fixed
status: open - closed

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[issue20113] os.readv() and os.writev() don't raise an OSError on readv()/writev() failure

2014-01-03 Thread Antoine Pitrou


Changes by Antoine Pitrou pit...@free.fr:


--
nosy: +rosslagerwall

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[issue16039] imaplib: unlimited readline() from connection