Re: How to access elemenst in a list of lists?
On Tuesday 10 May 2011 11:25:59 Terry Reedy wrote: > On 5/9/2011 8:44 PM, Algis Kabaila wrote: > > The method of double indexing in the manner > > a[i][j] > > for the (i, j) -th element of multi-dimensional array is > > well known and widely used. But how to enable the > > "standard" matrix notation a[i, j] > > in Python 3.2 in the manner of numpy (and other matrix > > packages)? Is it subclassing of "special methods" > > > > __getitem__() # to get > > > > __setitem__() # to set > > Yes. > > class listwrap: > def __init__(self, lis): > self._list = lis > def __getitem__(self, dex): > i,j = dex > return self._list[i][j] > # __setitem__: exercise for reader > > l = listwrap([[1,2,3],['a','b','c']]) > print(l[0,2],l[1,0]) > # 3 a > > IMO, Hardly worth it for two dimensions. Terry, Thank you for your response. I have to confess that I do have the cludge of an answer to my own quesion, but it is a cludge; Your method looks much better, though I don't think it is complete - this subclassing of __getitem__ appears to stop simple list access, i.e. if li = [1, 2 ,3], it seems to me that print(li[2]) would raise an exception, no? However, the method that you have indicated is a neat way to solve the problem -- thank you for it! OldAl PS: just to confirm your method and the limitation of it "as is": It is NOT a criticism, just a mere observation, Good method, nice examle, great contribution! >>> 3 a Showing limitation of "as is" in this great method for access of list of lists Traceback (most recent call last): File "/dat/work/linalg/dim2.py", line 15, in print(ll[1]) File "/dat/work/linalg/dim2.py", line 6, in __getitem__ i,j = dex TypeError: 'int' object is not iterable >>> -- Algis http://akabaila.pcug.org.au/StructuralAnalysis.pdf -- http://mail.python.org/mailman/listinfo/python-list
Re: How to access elemenst in a list of lists?
On Tuesday 10 May 2011 17:22:42 Algis Kabaila wrote:
> On Tuesday 10 May 2011 11:25:59 Terry Reedy wrote:
> > On 5/9/2011 8:44 PM, Algis Kabaila wrote:
> > > The method of double indexing in the manner
> > > a[i][j]
> > > for the (i, j) -th element of multi-dimensional array is
> > > well known and widely used. But how to enable the
> > > "standard" matrix notation a[i, j]
> > > in Python 3.2 in the manner of numpy (and other matrix
> > > packages)? Is it subclassing of "special methods"
> > >
> > > __getitem__() # to get
> > >
> > > __setitem__() # to set
> >
> > Yes.
> >
> > class listwrap:
> > def __init__(self, lis):
> > self._list = lis
> >
> > def __getitem__(self, dex):
> > i,j = dex
> > return self._list[i][j]
> >
> > # __setitem__: exercise for reader
> >
> > l = listwrap([[1,2,3],['a','b','c']])
> > print(l[0,2],l[1,0])
> > # 3 a
> >
> > IMO, Hardly worth it for two dimensions.
>
> Terry,
>
> Thank you for your response. I have to confess that I do
> have the cludge of an answer to my own question, but it is a
> cludge; Your method looks much better, though I don't think
> it is complete - this subclassing of __getitem__ appears to
> stop simple list access, i.e. if li = [1, 2 ,3], it seems to
> me that print(li[2])
> would raise an exception, no?
> However, the method that you have indicated is a neat way to
> solve the problem -- thank you for it!
>
> OldAl
>
> PS: just to confirm your method and the limitation of it "as
> is": It is NOT a criticism, just a mere observation, Good
> method, nice example, great contribution!
>
>
> 3 a
> Showing limitation of "as is" in this
> great method for access of list of lists
> Traceback (most recent call last):
> File "/dat/work/linalg/dim2.py", line 15, in
> print(ll[1])
> File "/dat/work/linalg/dim2.py", line 6, in __getitem__
> i,j = dex
> TypeError: 'int' object is not iterable
Apologies for accidental mail sending before it was completed:
The original code and additional data is as follows
l = listwrap([[1,2,3],['a','b','c']])
print(l[0,2],l[1,0])
print('''Showing limitation of "as is" in this
great method for access of list of lists''')
ll = listwrap([1,2,3])
print(ll[1])
Above is the output.
Thank you again,
Al.
--
Algis
http://akabaila.pcug.org.au/StructuralAnalysis.pdf
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Re: How to access elemenst in a list of lists?
On 5/10/2011 3:22 AM, Algis Kabaila wrote: On Tuesday 10 May 2011 11:25:59 Terry Reedy wrote: > class listwrap: > def __init__(self, lis): > self._list = lis > def __getitem__(self, dex): > i,j = dex > return self._list[i][j] > # __setitem__: exercise for reader > l = listwrap([[1,2,3],['a','b','c']]) > print(l[0,2],l[1,0]) > # 3 a Thank you for your response. I have to confess that I do have the cludge of an answer to my own quesion, but it is a cludge; Your method looks much better, though I don't think it is complete - this subclassing of __getitem__ appears to stop simple list access, i.e. if li = [1, 2 ,3], it seems to me that print(li[2]) would raise an exception, no? Yes, there really should be a guard condition: if isinstance(x tuple) or try: len(x) == 2. A __getattr__ method could be added to forwar other list methods to the wrapped list. One could try subclassing instead of wrapping, but some special methods have a fast path access for builtins that bypasses subclass methods. I think __getitem__ may be one such. Wrapping is safe in that respect. -- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
Steven D'Aprano wrote:
All very good, but that's not what takes place at the level of Python
code. It's all implementation.
Actually, you're right. What I've presented is a paper-and-pencil
implementation of the Python data model. Together with a set of
rules for manipulating the diagram under the direction of Python
code, you have a complete implementation of Python that you can
execute in your head.
And you NEED such an implementation in order to reason correctly
about Python programs under all circumstances.
I find it very difficult to imagine *any* implementation of
Python, computer-based or otherwise, that doesn't have something
equivalent to references. Whether you call them that, or pointers,
or arrows, or object bindings, or something else, the concept
needs to be there in some form.
But surely, if a = 1234 creates a reference from a to the big
box 1234, then b = a should create a reference from b to the box a?
+-+
+---+ | |
a | --+>| |
+---+ | |
^ +-+
|
+-|-+
b | | |
+---+
You can't expect anyone to draw correct conclusions from the
diagram alone; you also need to explain the rules for manipulating
the diagram under control of Python code.
Here, the explanation goes something like this:
1. The right hand side of an assignment denotes a big box. The
literal 1234 in a program denotes a big box containing the integer
value 1234.
2. The left hand side of an assignment denotes a little box. The
effect of an assignment is to make the arrow from the left hand
side's little box point to the big box denoted by the right hand
side.
So the assignment a = 1234 results in
+-+
+---+ | |
a | --+>| 1234 |
+---+ | |
+-+
3. When a name is used on the right hand side, it denotes whichever
big box is pointed to by the arrow from its little box. So given
the above diagram, the assignment b = a results in
+-+
+---+ | |
a | --+>| 1234 |
+---+ | |
+-+
^
+---+|
b | --+-
+---+
Furthermore, from rule 2 alone it's evident that no assignment
can ever make an arrow lead from one little box to another
little box. Arrows can only lead from a little box to a big
box.
That's how it works in C and Pascal (well, at least with the appropriate
type declarations).
Um, no, it doesn't, really. There's no way 'b = a' can give
you that in C; you would have to write 'b = &a'. And you
couldn't do it at all in standard Pascal, because there is
no equivalent to the & operator there.
Your model is closer to what the CPython implementation
actually does,
I think it's close -- actually, I would say isomorphic --
to what *any conceivable* Python implementation would do in
some form.
n = len('hello world')
What about outside len? Where's the little box
pointing to 'hello world'?
So it seems your model fails to deal with sufficiently anonymous objects.
Anonymous objects are fine. You just draw a little box and
don't write any label beside it. Or you don't bother drawing
a little box at all and just draw a big box until such time
as some little box that you care about needs to point to it.
If that's a problem, then you have the same problem talking
about names bound to objects. An anonymous object obviously
doesn't have any name bound to it. So you have to admit that
objects can exist, at least temporarily, without being bound
to anything, or bound to some anonymous thing.
Both the call to len and the call to func push their results onto the
stack. There's no little box pointing to the result.
If you want to model things at that level of detail, then the
stack itself is an array of little boxes inside a frame object.
And the frame object is pointed to by a little box in its
calling frame object, etc. until you get to some global little
box, that doesn't have a name in Python, but exists somewhere
and keeps the chain of active stack frames alive.
But you don't have to draw any of that if you don't want to.
For practical reasons, there must be some sort of
indirection. But that's implementation and not the VM's model.
No, it's not just implementation. Indirection is needed for
*correct semantics*, not just practicality.
There is a problem with my model of free-floating objects in space: it
relies on objects being able to be in two places at once,
Yes, that's the point I'm trying to make. While it might be
possible to make such a model wor
Re: Overuse of try/except/else?
James Mills wrote: On Tue, May 10, 2011 at 10:40 AM, Kyle T. Jones wrote: It has been hard for me to determine what would constitute overuse. A rule of thumb I always follow and practice is: "Let the error lie where it occurred." or "Don't hide errors.". It's good practice to follow IHMO as it makes it easier to find the source of defects in your function(s). If you constantly do things like try/except/log then it makes finding the source harder and may make it harder to identify what caused it. You can reraise the exception without loosing the stack trace. try: ... except SomeException, exc: log(exc) print 'Hello world' raise # "raise exc" would loose the original stack trace JM PS : "code that crashes could use improvement, but incorrect code that doesn’t crash is a horrible nightmare." (I don't know the author) -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On Tue, May 10, 2011 at 12:29 AM, Steven D'Aprano wrote: > If objects can be in two places at once, why can't names? Just because. Because then you'd need some way to identify which object you wanted to refer to - something like name[0] and name[1]. A tuple is one effective way to do this (sort of - actually, the name points at the tuple and the tuple points at each of the objects). On Tue, May 10, 2011 at 12:47 PM, MRAB wrote: > I had heard something about the meaning of the word "gift", so I > checked in Google Translate. For Swedish "gift" it says: > > noun > 1. POISON > 2. VENOM > 3. TOXIN > 4. VIRUS Beware of Swedes bearing gifts! On Tue, May 10, 2011 at 5:41 PM, Gregory Ewing wrote: > Anonymous objects are fine. You just draw a little box and > don't write any label beside it. Or you don't bother drawing > a little box at all and just draw a big box until such time > as some little box that you care about needs to point to it. > > If that's a problem, then you have the same problem talking > about names bound to objects. An anonymous object obviously > doesn't have any name bound to it. So you have to admit that > objects can exist, at least temporarily, without being bound > to anything, or bound to some anonymous thing. There has to be a way to get from some mythical "home" location (which we know in Python as locals()+globals()+current expression - the "current namespace") to your object. That might involve several names, or none at all, but if there's no such path, the object is unreferenced and must be disposed of. IIRC that's not just an implementation detail (the garbage collector), but a language guarantee (that the __del__ method will be called). Names are immaterial to that. Chris Angelico -- http://mail.python.org/mailman/listinfo/python-list
Re: A suggestion for an easy logger
Vinay Sajip wrote:
> No, you can pass keyword arguments in any order - that's what makes
> them keyword, as opposed to positional, arguments.
I getting puzzled :)
==code==
myself@laptop-~> python
Python 3.2 (r32:88445, Apr 15 2011, 11:09:05)
[GCC 4.5.2 20110127 (prerelease)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import logging, sys
>>> logging.basicConfig(level=logging.DEBUG, format='%(message)s')
>>> sh = logging.StreamHandler(sys.stdout)
>>> sh.terminator = ''
>>> logging.getLogger().addHandler(sh)
>>> logging.debug('here we are')
here we are
here we are>>> print(logging.__version__)
0.5.1.2
==code==
Terminator is removed, but as you stated it's doing double print-out
One more point is, if you'd have the time to look back to one of the first
posts, that the leading *"DEBUG:root:"* doesn't show :-/
It's reported herein the version of Python and logging module's version.
For my thinking I'd go to look into the code and docs as well, to understand
what I should do to have my 4 way of logging.
I repeat, I'm very new on using logging module, but I should go in that way,
it isn't necessary to re-invent the wheel :).
Also I'd like to say that's only for my own learning, which I do as hobby.
--
goto /dev/null
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Re: can't get urllib2 or httplib to work with tor & privoxy
On Tue, May 10, 2011 at 4:20 AM, Bob Fnord wrote: > Both methods give me a 503 error... As a networking geek, my first thought would be to fire up a tiny little "snoop server" and see what, exactly, the two methods are doing. (Ignore the HTTPS options as they're more complicated to snoop on; you're almost certainly going to see exactly the same on the HTTP.) A snoop server is simply an HTTP server that dumps its requests to stdout or a file, utterly raw. You can write one in Python fairly easily, or use another program; if I'm working on Windows, I'll generally use my own RosMud MUD client, but you'll be able to whip up a cross-platform one in half a page of code in any decent high level language. I recommend you work at the sockets level, rather than using an HTTP library, unless you have one that can emit the entire request, exactly as it came from the client. Once you've found the difference(s) between Lynx and your script, you can see what's causing the 503 (Service Unavailable) error; it may be that you need to authenticate with the proxy. Chris Angelico -- http://mail.python.org/mailman/listinfo/python-list
Re: How to access elemenst in a list of lists?
On Tuesday 10 May 2011 17:44:44 Terry Reedy wrote: > On 5/10/2011 3:22 AM, Algis Kabaila wrote: > > On Tuesday 10 May 2011 11:25:59 Terry Reedy wrote: > > > class listwrap: > > > def __init__(self, lis): > > > self._list = lis > > > > > > def __getitem__(self, dex): > > > i,j = dex > > > return self._list[i][j] > > > > > > # __setitem__: exercise for reader > > > > > > l = listwrap([[1,2,3],['a','b','c']]) > > > print(l[0,2],l[1,0]) > > > # 3 a > > > > Thank you for your response. I have to confess that I do > > have the cludge of an answer to my own quesion, but it is > > a cludge; Your method looks much better, though I don't > > think it is complete - this subclassing of __getitem__ > > appears to stop simple list access, i.e. if li = [1, 2 > > ,3], it seems to me that print(li[2]) would raise an > > exception, no? > > Yes, there really should be a guard condition: if > isinstance(x tuple) or try: len(x) == 2. A __getattr__ > method could be added to forwar other list methods to the > wrapped list. One could try subclassing instead of wrapping, > but some special methods have a fast path access for > builtins that bypasses subclass methods. I think __getitem__ > may be one such. Wrapping is safe in that respect. Actually, I am working on an array class that subclasses list. My interest is to have a module that deals with matrices with pure Python 3.2 or higher. The class would need to deal with many different arrays and matrix operations between them. In since Array subclasses list, any modifications of __getitem__ ir __setitem__ would naturally be in the array class and would in fact subclass the list special methods if implemented in the Array class. And, to my chagrin, I do manage to mess it up... Thanks for your bright suggestion, OldAl. -- Algis http://akabaila.pcug.org.au/StructuralAnalysis.pdf -- http://mail.python.org/mailman/listinfo/python-list
Re: Overuse of try/except/else?
On Mon, 2011-05-09 at 19:40 -0500, Kyle T. Jones wrote: > It has been hard for me to determine what would constitute overuse. The chronic problem is under use; so I wouldn't worry much about it. try/except should occur as often as is required for the application to either deal gracefully with the condition or report *meaningful* error messages to the user/administrator. -- http://mail.python.org/mailman/listinfo/python-list
Re: Testing tools classification
On May 10, 8:55 am, "Gabriel Genellina" wrote: > En Sat, 07 May 2011 02:21:02 -0300, rusi escribió: > > > There is this nice page of testing tools taxonomy: > >http://pycheesecake.org/wiki/PythonTestingToolsTaxonomy > > > But it does not list staf:http://staf.sourceforge.net/index.php. > > The good thing about wikis is, you can add it yourself. > > -- > Gabriel Genellina Could not figure out how to get edit rights. [Which is all for the good considering what a testing-ignoramus I am :-) ] -- http://mail.python.org/mailman/listinfo/python-list
Re: Overuse of try/except/else?
On Tue, 10 May 2011 07:36:42 -0400, Adam Tauno Williams wrote: : On Mon, 2011-05-09 at 19:40 -0500, Kyle T. Jones wrote: : > It has been hard for me to determine what would constitute overuse. : : The chronic problem is under use; so I wouldn't worry much about it. : : try/except should occur as often as is required for the application to : either deal gracefully with the condition or report *meaningful* error : messages to the user/administrator. So overuse is really when you cannot do anything meaningful about the exception. The two interesting questions are really 1. where and when to catch a given exception 2. at what stage of the development cycle catching a particular (class of) exception should become a priority There is a potential overuse of exceptions, where they are used for quite ordinary and frequent (i.e. not exceptional) conditions, and the information could be passed through the return value instead. Exceptions is a very flexible, but also rather expensive means of communications. You can, actually, write any program using raise instead of return. That would be overuse. -- :-- Hans Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On 2011-05-10, Gregory Ewing wrote: > Steven D'Aprano wrote: > >> It's just that the term "variable" is so useful and so familiar that it's >> easy to use it even for languages that don't have variables in the C/ >> Pascal/Fortran/etc sense. > > Who says it has to have the Pascal/Fortran/etc sense? Because it's easier to communicate if everybody agrees on what a word means. -- Grant Edwards grant.b.edwardsYow! The SAME WAVE keeps at coming in and COLLAPSING gmail.comlike a rayon MUU-MUU ... -- http://mail.python.org/mailman/listinfo/python-list
Re: string formatting
On Wed, May 11, 2011 at 12:15 AM, Web Dreamer wrote:
> I was unsure of the difference between deprecated and obsolete.
>
> So now, if I understand well, obsolete comes before deprecated, such that if
> a feature is obsolete it will be deprecated in an unknown future, after
> which it will be removed once it has been deprecated (a certain time after
> it was rendered obsolete)?
> (might need an aspirin to read that one :-) )
>
> So If I'm right, old string formatting "could" one day be deprecated but it
> is not yet?
I wouldn't say that obsolete features "will be" deprecated. That
expression makes little sense (I know, for I have seen it in eBay's
API documentation, and it did not fill me with joy). Deprecation is
(usually) a formal procedure that clearly states that a feature should
not be used. It may be accompanied by a strict cutoff ("will be
removed in version X"), or just left vague, but linting tools can
identify all use of deprecated features.
Obsolete, however, is simply a description. Sopwith Camels were
obsolete in the second world war, and VHS has been obsoleted by
optical disc media. However, if you wish to fly a Camel or play a VHS,
nothing's stopping you. The sky will still accept your Camel, and your
VHS player will still talk to your television. (The analogy breaks
down a bit in that your obsolete VHS player may be using a deprecated
cabling style, but it's coax that's deprecated, not VHS.) There's no
"projected end date" for them.
Generally, a feature is obsolete before it's deprecated, but
technically that's not a requirement, and API designers can sometimes
be quite arbitrary. On the other hand, obsolescence is quite informal,
and people can disagree about whether or not something is. (Hi Ken,
your continued use of inches is noted. Thank you.)
Chris Angelico
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Re: What other languages use the same data model as Python?
On Tue, 10 May 2011 14:05:34 + (UTC), Grant Edwards wrote: : Because it's easier to communicate if everybody agrees on what a word : means. Why should we agree on that particular word? Are there any other words we agree about? Other key words, such as class, object, or function don't have universal meanings. :-) -- :-- Hans Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On 2011-05-10, Hans Georg Schaathun wrote: > On Tue, 10 May 2011 14:05:34 + (UTC), Grant Edwards > wrote: >: Because it's easier to communicate if everybody agrees on what a word >: means. > > Why should we agree on that particular word? Are there any other words > we agree about? Other key words, such as class, object, or function don't > have universal meanings. And what do we mean by "agree"? What do we mean by "mean"? It's turtles all they down... -- Grant Edwards grant.b.edwardsYow! at gmail.com -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On Wed, May 11, 2011 at 1:16 AM, Grant Edwards wrote: > And what do we mean by "agree"? > > What do we mean by "mean"? > > It's turtles all they down... When I use a word, it means just what I choose it to mean - neither more nor less. -- Humpty Dumpty. Language is for communication. If we're not using the same meanings for words, we will have problems. Chris Angelico PS. By "mean", I mean average. Except when I mean mean. But now I'm just being mean. -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On Wed, 11 May 2011 01:27:36 +1000, Chris Angelico wrote: : Language is for communication. If we're not using the same meanings : for words, we will have problems. So if you adopt the word class to mean a type (or composite type), as in python, what word would you use for a class of types (as in haskell or ada)? I think there are too many meanings and too few words ... That's why some languages support overloading. I am afraid we just need to cope with it, overloading I mean. -- :-- Hans Georg -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On Wed, May 11, 2011 at 1:40 AM, Hans Georg Schaathun wrote: > On Wed, 11 May 2011 01:27:36 +1000, Chris Angelico > wrote: > : Language is for communication. If we're not using the same meanings > : for words, we will have problems. > > So if you adopt the word class to mean a type (or composite type), > as in python, what word would you use for a class of types (as in > haskell or ada)? > > I think there are too many meanings and too few words ... > > That's why some languages support overloading. Of course. Nobody ever said that one name had to point to one value... oh wait. Yes, Virginia, there is overloading. Chris Angelico -- http://mail.python.org/mailman/listinfo/python-list
Re: scipy
On Sun, 8 May 2011 03:44:06 -0700 (PDT), pb wrote: : I', having trouble with scipy. I have followed the instructions at : scipy website and have installed the following on my mac osx 10.6.6 : (...) : I'm assuming I have the wrong version of something, would that be : right? : Does anyone know how I can fix this? I had the same problem, but assumed that it was more likely to be a bug in the unit tests than a bug anywhere else. But then I mainly use linux boxen to run the stuff, so a bug on the mac installation does not bother me much. Installing software on a mac is just painful. -- :-- Hans Georg -- http://mail.python.org/mailman/listinfo/python-list
Non Programming in python
Sorry for a silly subject change: A better one will be welcome -- cant
think of a name myself.
There is this whole area of python that may be called the non-
programming side of programming:
Is there some central site where all such is put up?
What if any should such a bundle of things be called?
-
| Area | Tool(s)|
|--+|
| packaging| distutils, setuptools, |
| | distutils2, distribute |
| | Native tools (eg apt) |
| versioning | hg, git, bzr |
| multiple pythons | virtualenv |
| ?? | tox|
| testing | unittest, nose, pytest |
| build| scons, make... |
| deployment | fabric |
--
* Primary Development tools/aids
1. Help
2. Completion ('intellisense')
3. Tags (Jumping)
4. Refactoring
5. Integration with 'non-programming' above (eg VCSes, packagers
etc)
* Other Development Tools
- Debugger
- Profiler
- Heap Profiler
- Coverage
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Python-URL! - weekly Python news and links (May 10)
[This content provided by Gabriel Genellina, despite what the "From:" line says.] QOTW: "Often, the cleverness of people is inversely proportional to the amount of CPU power and RAM that they have in their computer. Unfortunately, the difficulty in debugging and maintaining code is often directly proportional to the cleverness exhibited by the original programmer." - Irmen de Jong and Grant Edwards http://groups.google.com/group/comp.lang.python/t/58559ead6dc82448 Looking for "The Coolest Python Recipe of All Times": http://groups.google.com/group/comp.lang.python/t/141fdde77caab932 A nice and clever probabilistic data structure: http://groups.google.com/group/comp.lang.python/t/58559ead6dc82448 Development tools and best practices (continued from previous week): http://groups.google.com/group/comp.lang.python/t/836537e6c25cf027 Things to be aware of when using dictionary views: http://groups.google.com/group/comp.lang.python/t/b9c6ded7522e7425 Python3 and absolute/relative imports: http://groups.google.com/group/comp.lang.python/t/9470dbdacc138709 Another gotcha when using import with packages: http://groups.google.com/group/comp.lang.python/t/961a90219a61e19d Fibonacci, recursion, and the 'P' conspiracy theory: http://groups.google.com/group/comp.lang.python/t/b713b14e3e0d9872 The preferred way for string formatting: http://groups.google.com/group/comp.lang.python/t/f0cd2717ffe13560 Checking if a list is empty - and how to think "the Python way": http://groups.google.com/group/comp.lang.python/t/d36dcd2e2e175d1e Classics never die: What other languages use the same data model as Python? http://groups.google.com/group/comp.lang.python/t/4b8b0e06a2d5cfcc Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html Just beginning with Python? This page is a great place to start: http://wiki.python.org/moin/BeginnersGuide/Programmers Planet Python: you want to visit there: http://planet.python.org But don't confuse it with Planet SciPy: http://planet.scipy.org And don't confuse *that* with SciPyTip, a high-quality daily (!) tip for the numerically-inclined: http://twitter.com/SciPyTip Python Insider is the official blog of the Python core development team: http://pyfound.blogspot.com/2011/03/python-dev-launches-python-insider-blog.html The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donations/ Keep up with the PSF at "Python Software Foundation News": http://pyfound.blogspot.com The Python Papers aims to publish "the efforts of Python enthusiasts": http://pythonpapers.org/ Doug Hellman's "Module of the week" is essential reading: http://www.doughellmann.com/PyMOTW/ comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/group/comp.lang.python.announce/topics Python411 indexes "podcasts ... to help people learn Python ..." Updates appear more-than-weekly: http://www.awaretek.com/python/index.html The Python Package Index catalogues packages. http://www.python.org/pypi/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Summary of Python Tracker Issues is an automatically generated report summarizing new bugs, closed ones, and patch submissions. http://search.gmane.org/?author=status%40bugs.python.org&group=gmane.comp.python.devel&sort=date nullege is an interesting search Web application, with the intelligence to distinguish between Python code and comments. It provides what appear to be relevant results, and demands neither Java nor CSS be enabled: http://www.nullege.com Although unmaintained since 2002, the Cetus collection of Python hyperlinks retains a few gems. http://www.cetus-links.org/oo_python.html Python FAQTS http://python.faqts.com/ The Cookbook is a collaborative effort to capture useful and interesting recipes: http://code.activestate.com/recipes/langs/python/
Re: Dictionary Views -- good examples? [was Re: Python 3 dict question]
Ian Kelly wrote: On Fri, May 6, 2011 at 4:49 PM, Ethan Furman wrote: Anybody care to chime in with their usage of this construct? You should start with PEP 3106. The main idea is that dict.keys() and dict.items() can be treated as frozensets, while still being more lightweight than lists. That lets you do nifty things like "a.keys() == b.keys()" which, if a and b are Python 3 dicts, will tell you whether they contain the same keys. Cool, thanks. ~Ethan~ -- http://mail.python.org/mailman/listinfo/python-list
Re: string formatting
> Which is the preferred way of string formatting?
>
> (1) "the %s is %s" % ('sky', 'blue')
>
> (2) "the {0} is {1}".format('sky', 'blue')
>
> (3) "the {} is {}".format('sky', 'blue')
>
> As I know (1) is old style. (2) and (3) are new but (3) is only
> supported from Python 2.7+.
>
> Which one should be used?
Sometimes, I use both ;-)
That can save you from ugly escapes such as %%s or {{0}}.
Here's an example from the standard library:
http://hg.python.org/cpython/file/7254c03b7180/Lib/collections.py#l235
Note the template has both {typename} formatting for the first pass
and %r style formatting in the generated code.
Raymond
follow my tips and recipes on twitter: @raymondh
--
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Re: Python 3 dict question
On May 6, 12:40 pm, dmitrey wrote: > hi all, > suppose I have Python dict myDict and I know it's not empty. > I have to get any (key, value) pair from the dict (no matter which > one) and perform some operation. > In Python 2 I used mere > key, val = myDict.items()[0] > but in Python 3 myDict.items() return iterator. > Of course, I could use > for key, val in myDict.items(): > do_something > break > but maybe there is any better way? If your use case allows the item to be removed, then use: key, val = myDict.popitem() Otherwise, use: key, val = next(iter(MyDict.items())) The latter is nice because next() allows you to supply a default argument in case the dictionary is emtpy: key, val = next(iter(MyDict.items()), (None, None)) Raymond - follow my tips and recipes on twitter: @raymondh -- http://mail.python.org/mailman/listinfo/python-list
Re: vertical ordering of functions
On Tue, 3 May 2011 18:08:27 -0400, Jabba Laci wrote: : I'm just reading Robert M. Martin's book entitled "Clean Code". In Ch. : 5 he says that a function that is called should be below a function : that does the calling. This creates a nice flow down from top to : bottom. My advice would be to order it in the same way as you would if you were presenting the algorithm in a paper. >From such a viewpoint, it depends on whether you consider the called names to be terms which need definitions, or operations with an intutive purpose, merely requiring an explanation (implentation) of how it is done. In a paper that means that definitions must come before the theorems and lemmata very often between the theorem and its proof. If you don't write papers, that may not be particularly useful :-) In programming, it means that names which have self-explanatory name may very well be called first and defined later. The caller will give a high-level view of what is going on. The callees are building blocks whose purpose can be understood immediately, and whose inner workings can be sought further down the file. Fundamental definitions which may be as easy to implement as explain may often come first. The question here, is didactics and not programming per se. A simple rule does not make complex code significantly easier to read, but a thought structure of the code (with comments and choice of names) over-all does. And let's not forget that calls may be circular or otherwise convolved in a way that does not allow consistent sorting of caller before/after callee. -- :-- Hans Georg -- http://mail.python.org/mailman/listinfo/python-list
This it is the code of tmb_import.py (to matter of .tmb to blender) I need tmb_exporter.py (to export of blender to .tmb) Thanks.
I need help. Hello. The attached file is script of blender fact in python that .tmb serves to concern archives (secondly attached file), unloadings to blender and uses script and concerns the second file that you shipment you see so that it. Everything can be published and, but it is not possible to be exported again to .tmb To unload in this Link: http://www.blender.org/ script: http://www.mediafire.com/?clmdgkymsfooddd secondly attached file: http://www.mediafire.com/?lbmj594ru6r4b67 PD: I need script to export in extension .tmb Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
On 5/10/2011 3:41 AM, Gregory Ewing wrote: Actually, you're right. What I've presented is a paper-and-pencil implementation of the Python data model. Together with a set of rules for manipulating the diagram under the direction of Python code, you have a complete implementation of Python that you can execute in your head. I think that it would be both fun and useful to have an animated graphical tutorial that used and box and arrow model. Names should be in ovals (instead of the little boxes used here due to text limitations) to differentiate them from objects. Immutable objects could have solid boundaries and mutables a broken line boundary. Collection objects would have dotted lines to separate slots. Ovals could also use different lines for builtins, globals, and locals. And you NEED such an implementation in order to reason correctly about Python programs under all circumstances. I find it very difficult to imagine *any* implementation of Python, computer-based or otherwise, that doesn't have something equivalent to references. Whether you call them that, or pointers, or arrows, or object bindings, or something else, the concept needs to be there in some form. Since namespaces link names in a namespace with objects not in the namespace, any practical implementation needs a third entity to link or associated each name with an object. This is pretty much needed to explain multiple links without objects being in multiple locations. It is also needed to explain how an object can link to itself. -- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Non Programming in python
On 5/10/2011 12:41 PM, rusi wrote:
Sorry for a silly subject change: A better one will be welcome -- cant
think of a name myself.
Associated tools. I might separate them into development tools (up to
the production of python.exe) and usage tools (everything thereafter).
On Windows, this is a pretty clean separation. On Linux, less so since
users sometimes build their own binaries and therefore use some of the
development tools.
Assuming that there is not one already, this could be the beginning of a
useful overview wiki page with links to existing pages on the specific
topics ('areas') listed below.
There is this whole area of python that may be called the non-
programming side of programming:
Is there some central site where all such is put up?
What if any should such a bundle of things be called?
-
| Area | Tool(s)|
|--+|
| packaging| distutils, setuptools, |
| | distutils2, distribute |
| | Native tools (eg apt) |
| versioning | hg, git, bzr |
| multiple pythons | virtualenv |
| ?? | tox|
| testing | unittest, nose, pytest |
| build| scons, make... |
| deployment | fabric |
--
I would reorder this list in the typical order used, starting with editors.
* Primary Development tools/aids
1. Help
2. Completion ('intellisense')
3. Tags (Jumping)
4. Refactoring
5. Integration with 'non-programming' above (eg VCSes, packagers
etc)
* Other Development Tools
- Debugger
- Profiler
- Heap Profiler
- Coverage
--
Terry Jan Reedy
--
http://mail.python.org/mailman/listinfo/python-list
Re: What other languages use the same data model as Python?
Chris Angelico wrote: There has to be a way to get from some mythical "home" location (which we know in Python as locals()+globals()+current expression - the "current namespace") to your object. That might involve several names, or none at all, but if there's no such path, the object is unreferenced and must be disposed of. Yes, that's what I mean by "bound to some anonymous thing". Somewhere in the implementation there must be one or more "root" references, but they don't necessarily have any names that you can refer to from Python. When I say "not bound to any name", I just mean that it's okay to leave some bindings out of your diagram if they're not pertinent to what you're trying to illustrate. For example, you can draw a box representing a string object and trust that something will keep it alive long enough for you to draw an arrow to it from the name you're assigning it to. -- Greg -- http://mail.python.org/mailman/listinfo/python-list
Re: Non Programming in python
On Tue, 10 May 2011 09:41:19 -0700, rusi wrote: > Sorry for a silly subject change: A better one will be welcome -- cant > think of a name myself. > > There is this whole area of python that may be called the non- > programming side of programming: > > Is there some central site where all such is put up? What if any should > such a bundle of things be called? Documentation. Check the Python wiki. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Python backup programs?
What are your favorite backup programs written, in whole or in part, in Python? What do you like about them? Dislike about them? Are there any features you wish your backup program had, whether in Python or not? Thanks! -- http://mail.python.org/mailman/listinfo/python-list
Re: Python backup programs?
On Wed, May 11, 2011 at 9:00 AM, Dan Stromberg wrote: > > What are your favorite backup programs written, in whole or in part, in > Python? > > What do you like about them? Dislike about them? > > Are there any features you wish your backup program had, whether in Python > or not? Recently I wrote a simple backup system for a client using a mixture of Python and Bash using rsync, ssh and pptp. (Not packaged well enough to show source though) It works very well and does the job. cheers James -- -- James Mills -- -- "Problems are solved by method" -- http://mail.python.org/mailman/listinfo/python-list
Re: This it is the code of tmb_import.py (to matter of .tmb to blender) I need tmb_exporter.py (to export of blender to .tmb) Thanks.
En Tue, 10 May 2011 15:51:03 -0300, Jean Carlos Páez Ramírez escribió: The attached file is script of blender fact in python that .tmb serves to concern archives (secondly attached file), unloadings to blender and uses Por lo que pude entender, tu problema es bastante específico de Blender, así que tal vez te convenga preguntar en un foro como: http://www.g-blender.org/ (específicamente dedicado a Blender 3D en español) También está la comunidad de Python Argentina: http://python.org.ar/pyar/ (busca la lista de correo) Suerte! -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Overuse of try/except/else?
On 05/09/2011 07:40 PM, Kyle T. Jones wrote: It has been hard for me to determine what would constitute overuse. Cheers. Well, for me the power of exceptions is that it lets me write much more concise code. For example, suppose I call a routine I wrote over and over, and I have to check for errors on each call. Then you have a long block of code like: if err == 0: x1,err=somefunction(1) if err == o: x2,err=somefunction(2) ... ... but if somefunction just raises an exception on error, then you do try: x1=somefunction(1) x2=somefunction(2) ... ... except: blah blah So for my uses, its handy to let things raise exceptions willy nilly in the lower level functions, and do the catching in the higher level function. Paul Probert -- http://mail.python.org/mailman/listinfo/python-list
Re: Overuse of try/except/else?
On Tue, May 10, 2011 at 7:34 PM, Jean-Michel Pichavant wrote: > You can reraise the exception without loosing the stack trace. > > try: > ... > except SomeException, exc: > log(exc) > print 'Hello world' > raise # "raise exc" would loose the original stack trace Valid point :) However I was referring to real experience where I've seen code that "catches all any any exception" and simply logs it. cheers James -- -- James Mills -- -- "Problems are solved by method" -- http://mail.python.org/mailman/listinfo/python-list
Re: Non Programming in python
On May 11, 12:28 am, Terry Reedy wrote:
> On 5/10/2011 12:41 PM, rusi wrote:
>
> > Sorry for a silly subject change: A better one will be welcome -- cant
> > think of a name myself.
>
> Associated tools. I might separate them into development tools (up to
> the production of python.exe) and usage tools (everything thereafter).
> On Windows, this is a pretty clean separation. On Linux, less so since
> users sometimes build their own binaries and therefore use some of the
> development tools.
Can you elaborate? I dont understand
>
> Assuming that there is not one already, this could be the beginning of a
> useful overview wiki page with links to existing pages on the specific
> topics ('areas') listed below.
>
>
>
> > There is this whole area of python that may be called the non-
> > programming side of programming:
>
> > Is there some central site where all such is put up?
> > What if any should such a bundle of things be called?
>
> > -
>
> > | Area | Tool(s) |
> > |--+|
> > | packaging | distutils, setuptools, |
> > | | distutils2, distribute |
> > | | Native tools (eg apt) |
> > | versioning | hg, git, bzr |
> > | multiple pythons | virtualenv |
> > | ?? | tox |
> > | testing | unittest, nose, pytest |
> > | build | scons, make... |
> > | deployment | fabric |
>
> > --
>
> I would reorder this list in the typical order used, starting with editors.
>
> > * Primary Development tools/aids
>
> > 1. Help
> > 2. Completion ('intellisense')
> > 3. Tags (Jumping)
> > 4. Refactoring
> > 5. Integration with 'non-programming' above (eg VCSes, packagers
> > etc)
>
> > * Other Development Tools
> > - Debugger
> > - Profiler
> > - Heap Profiler
> > - Coverage
Some more 'areas':
1. Which python 'form' does one use?
At the least python vs pythonw on windows.
But more generally scripting vs REPL. In REPL python vs ipython
Note 1. I am often unnerved by how even experienced python programmers
think that the only way to 'do' python is like C -- write a main, not
appreciating the luxury of an unstructured, exploratory mode that an
REPL makes possible.
Note 2. ruby makes this distinction more obvious by distinguishing the
scripting engine -- ruby -- form the interactive interpreter (REPL) --
irb.
2. Literate Programming: When the primary purpose of the program is
not the program but (some form of) discussion around it
3. Program namespace lookup and structuring: sys.path is the interior
program view but there is also the 'exterior' view -- PYTHONPATH, .pth
files etc.
Finally some thoughts on how to name this list of areas:
a. Software Engineering? : Inasmuch as real program development is
programming + 'something-else' and SE is that 'something else'
b. Python Development Environment? Similar to above
[Cannot say I like these names too much but at least its more specific
than Steven's vanilla 'documentation' :-) ]
--
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Merge multiple source directories into one package with distutils?
Is there a straightforward way to tell distutils to merge .py files from more than one source directory into a single package when installing? PyGUI consists of some generic modules and some platform specific ones, that conceptually all live at the same level within a single package. In the source, there is a subdirectory for each platform containing the platform-dependent files. When run from the source, __path__ manipulation is done to make the appropriate platform subdirectory appear to be part of the main package. However, when installing, I would like to just copy the generic files plus the relevant platform ones directly into the destination package directory, so that __path__ fiddling is not needed. This is so that bundling tools such as py2app and py2exe can find all the relevant modules without requiring any hacking. But distutils doesn't appear to support this. Unless I'm missing something, you only get to specify one source directory for each package. Anyone have any ideas for getting around this? -- Greg -- http://mail.python.org/mailman/listinfo/python-list
Re: Python backup programs?
Le 11/05/2011 01:57, James Mills a écrit : > On Wed, May 11, 2011 at 9:00 AM, Dan Stromberg wrote: >> >> What are your favorite backup programs written, in whole or in part, in >> Python? My favorite one is the one I wrote myself for myself ;) The point I like : 1. the backup is a simple copy. I can retrieve it without any specific programs. 2. if a file changed, before to be copied, the backup file is moved to a specific repertory whose name is the date and hour. So if I destroy a file and backup the destroyed one, the old non-destroyed one is still available. 3. Since the program is anyway performing a long os.walk operation, in the same time, it performs `git commit` in the directories that need it. 4. My program is command-line only. Works fine in tty Points that are of no importance (very personal and adapted to my specific case !) : 1. time. One backup takes between 10 minutes and one hour. I don't really care. 2. space. Since my backup is a copy (and copy of copies), my backup directory takes ~150Go while my home is about 25 Go. Hope it answer your question. Have a nice day Laurent -- http://mail.python.org/mailman/listinfo/python-list
