Re: Python 3.0 automatic decoding of UTF16
Johannes Bauer [EMAIL PROTECTED] writes: Traceback (most recent call last): File ./modify.py, line 12, in module a = AddressBook(2008_11_05_Handy_Backup.txt) File ./modify.py, line 7, in __init__ line = f.readline() File /usr/local/lib/python3.0/io.py, line 1807, in readline while self._read_chunk(): File /usr/local/lib/python3.0/io.py, line 1556, in _read_chunk self._set_decoded_chars(self._decoder.decode(input_chunk, eof)) File /usr/local/lib/python3.0/io.py, line 1293, in decode output = self.decoder.decode(input, final=final) File /usr/local/lib/python3.0/codecs.py, line 300, in decode (result, consumed) = self._buffer_decode(data, self.errors, final) File /usr/local/lib/python3.0/encodings/utf_16.py, line 69, in _buffer_decode return self.decoder(input, self.errors, final) UnicodeDecodeError: 'utf16' codec can't decode bytes in position 74-75: illegal encoding It probably means what it says: that the input file contains characters it cannot read using the specified encoding. Are you generating the file from python using a file object with the same encoding? If not, then you might want to look at your input data and find a way to deal with the exception. -- http://mail.python.org/mailman/listinfo/python-list
Re: RELEASED Python 3.0 final
Barry Warsaw [EMAIL PROTECTED] writes: On behalf of the Python development team and the Python community, I am happy to announce the release of Python 3.0 final. Yay! Thanks for all the great work. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python equivalent of Common Lisp Macros?
dpapathanasiou [EMAIL PROTECTED] writes:
I'm using the feedparser library to extract data from rss feed items.
After I wrote this function, which returns a list of item titles, I
noticed that most item attributes would be retrieved the same way,
i.e., the function would look exactly the same, except for the single
data.append line inside the for loop.
In CL, I could simply write a macro, then replace the data.append line
depending on which attribute I wanted.
Is there anything similar in Python?
Here's the function:
def item_titles (feed_url):
Return a list of the item titles found in this feed url
data = []
feed = feedparser.parse(feed_url)
if feed:
if len(feed.version) 0:
for e in feed.entries:
data.append(e.title.encode('utf-8'))
return data
No macros -- need the whole code as data paradigm which doesn't exist
in python.
The pythonic way to create the sort of abstraction you're looking for
would be to use the *attr functions and either a map of attribute
identities or inspect the attributes from the objects.
Some UNTESTED code...
def extract_entry(e, attrs=['title', 'datetime', 'article']):
out = []
for attr in attrs:
assert hasattr(e, attr)
out.append(getattr(e, attr))
return out
Using the inspect module would give an even more generic function, but
with more complex code of course.
Then your code would look more like:
def items(feed_url):
feed = feedparser.feed(feed_url)
if feed and len(feed) 0:
return [extract_entry(entry) for entry in feed.entries]
Of course, I'm making liberal assumptions about what you're looking for
in your ouput here... but it's just an example, not a full
solution. YMMV. Hope it helps. :)
--
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Re: function parameter scope python 2.5.2
alex23 [EMAIL PROTECTED] writes: On Nov 21, 9:40 am, J Kenneth King [EMAIL PROTECTED] wrote: Of course, providing a shallow (or deep as necessary) copy makes it work, I'm curious as to why the value passed as a parameter to a function outside the class is passed a reference rather than a copy. You're passing neither a reference nor a copy, you're passing the object (in this case a list) directly: http://effbot.org/zone/call-by-object.htm Ah, thanks -- that's precisely what I was looking for. I knew it couldn't be a mistake; I just couldn't find the documentation on the behaviour since I didn't know what it was called in the python world. Cheers. -- http://mail.python.org/mailman/listinfo/python-list
Re: function parameter scope python 2.5.2
Steven D'Aprano [EMAIL PROTECTED] writes: On Thu, 20 Nov 2008 18:31:12 -0500, J Kenneth King wrote: Of course I expected that recursive_func() would receive a copy of weird_obj.words but it appears to happily modify the object. I am curious why you thought that. What made you think Python should/did make a copy of weird_obj.words when you pass it to a function? This is a serious question, I'm not trying to trap you into something :) Don't worry, I don't feel trapped in usenet. ;) It was more of an intuitive expectation than a suggestion that Python got something wrong. I was working on a program of some complexity recently and quickly caught the issue in my tests. I knew what was going on and fixed it expediently, but the behaviour confused me and I couldn't find any technical documentation on it so I figured I just didn't know what it was referred to in Python. Hence the post. :) I suppose I have some functional sensibilities and assumed that an object wouldn't let a non-member modify its properties even if they were mutable. Of course if there is any further reading on the subject, I'd appreciate some links. Cheers. -- http://mail.python.org/mailman/listinfo/python-list
Re: function parameter scope python 2.5.2
Peter Pearson [EMAIL PROTECTED] writes: On Fri, 21 Nov 2008 10:12:08 -0500, J Kenneth King wrote: Steven D'Aprano [EMAIL PROTECTED] writes: I am curious why you thought that. What made you think Python should/did make a copy of weird_obj.words when you pass it to a function? [snip] Of course if there is any further reading on the subject, I'd appreciate some links. As one relatively new Python fan to another, I recommend following this newsgroup. Many important aspects of Python that several books failed to drive through my skull are very clearly (and repeatedly) explained here. Hang around for a week, paying attention to posts with subjects like Error in Python subscripts (made-up example), and curse me if you don't find it greatly rewarding. I do lurk more often than I post and sometimes I help out people new to Python or new to programming in general. I know how helpful usenet can be and usually this group in particular is quite special. It's good advice to read before you post; quite often the question has been proposed and answered long before it came to your little head (not you in particular; just general you). In this case, I was simply lacking the terminology to find what I was looking for on the subject. In such cases turning to the community seems like a fairly reasonable way to find clarification. I've only been programming in Python specifically for two years or so now, so I hope I can be forgiven. Cheers. -- http://mail.python.org/mailman/listinfo/python-list
function parameter scope python 2.5.2
I recently encountered some interesting behaviour that looks like a bug to me, but I can't find the appropriate reference to any specifications to clarify whether it is a bug. Here's the example code to demonstrate the issue: class SomeObject(object): def __init__(self): self.words = ['one', 'two', 'three', 'four', 'five'] def main(self): recursive_func(self.words) print self.words def recursive_func(words): if len(words) 0: word = words.pop() print Popped: %s % word recursive_func(words) else: print Done if __name__ == '__main__': weird_obj = SomeObject() weird_obj.main() The output is: Popped: five Popped: four Popped: three Popped: two Popped: one Done [] Of course I expected that recursive_func() would receive a copy of weird_obj.words but it appears to happily modify the object. Of course a work around is to explicitly create a copy of the object property befor passing it to recursive_func, but if it's used more than once inside various parts of the class that could get messy. Any thoughts? Am I crazy and this is supposed to be the way python works? -- http://mail.python.org/mailman/listinfo/python-list
Re: function parameter scope python 2.5.2
J Kenneth King [EMAIL PROTECTED] writes: I recently encountered some interesting behaviour that looks like a bug to me, but I can't find the appropriate reference to any specifications to clarify whether it is a bug. Here's the example code to demonstrate the issue: class SomeObject(object): def __init__(self): self.words = ['one', 'two', 'three', 'four', 'five'] def main(self): recursive_func(self.words) print self.words def recursive_func(words): if len(words) 0: word = words.pop() print Popped: %s % word recursive_func(words) else: print Done if __name__ == '__main__': weird_obj = SomeObject() weird_obj.main() The output is: Popped: five Popped: four Popped: three Popped: two Popped: one Done [] Of course I expected that recursive_func() would receive a copy of weird_obj.words but it appears to happily modify the object. Of course a work around is to explicitly create a copy of the object property befor passing it to recursive_func, but if it's used more than once inside various parts of the class that could get messy. Any thoughts? Am I crazy and this is supposed to be the way python works? Of course, providing a shallow (or deep as necessary) copy makes it work, I'm curious as to why the value passed as a parameter to a function outside the class is passed a reference rather than a copy. -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiprocessing vs. [Pyro, RPyC]
Jeffrey Barish [EMAIL PROTECTED] writes: [EMAIL PROTECTED] wrote: Jeffrey With the release of multiprocessing in Python 2.6, is there any Jeffrey reason to use Pyro or RPyC? As far as I know the multiprocessing module only works on one machine (multi-cpu or multi-core), not across machines. So I thought at first, but then I saw this statement in the documentation: It is possible to run a manager server on one machine and have clients use it from other machines (assuming that the firewalls involved allow it). Depends. I don't know much about the multiprocessing module in 2.6, but I have built a distributed application on Pyro. Pyro has many advantages -- a query-able name server, GUI tools for monitoring your setup, and remote agents. It is also rather simple in comparison to other similar tools (*cough*twisted.pb*cough*). However, it is essentially an RPC style system, so some people might not be too comfortable with it. YMMV. -- http://mail.python.org/mailman/listinfo/python-list
Re: duck-type-checking?
Joe Strout [EMAIL PROTECTED] writes: Let me preface this by saying that I think I get the concept of duck- typing. However, I still want to sprinkle my code with assertions that, for example, my parameters are what they're supposed to be -- too often I mistakenly pass in something I didn't intend, and when that happens, I want the code to fail as early as possible, so I have the shortest possible path to track down the real bug. Also, a sufficiently clever IDE could use my assertions to know the type of my identifiers, and so support me better with autocompletion and method tips. So I need functions to assert that a given identifier quacks like a string, or a number, or a sequence, or a mutable sequence, or a certain class, or so on. (On the class check: I know about isinstance, but that's contrary to duck-typing -- what I would want that check to do instead is verify that whatever object I have, it has the same public (non-underscore) methods as the class I'm claiming.) Are there any standard methods or idioms for doing that? Thanks, - Joe I generally use the 'assert' keyword when I'm in a rush otherwise unit tests generally catch this kind of thing. -- http://mail.python.org/mailman/listinfo/python-list
Re: best python unit testing framwork
Brendan Miller [EMAIL PROTECTED] writes: What would heavy python unit testers say is the best framework? I've seen a few mentions that maybe the built in unittest framework isn't that great. I've heard a couple of good things about py.test and nose. Are there other options? Is there any kind of concensus about the best, or at least how they stack up to each other? Brendan I find nose to be the best. It's simple, easy, and doesn't sacrifice power. All good things if you value your time. :) -- http://mail.python.org/mailman/listinfo/python-list
Re: Daemon and logging - the best approach?
Lech Karol Pawłaszek [EMAIL PROTECTED] writes: Hello. I'm trying to make a daemon and I want to log to a file its activity. I'm using logging module with a configuration file for it (loaded via fileConfig()). And now I want to read logging config file before daemonize the program because the file might not be accessible after daemonization. OTOH while daemonizing I am closing all opened file descriptors - including those opened for logging. What is the best approach to handle such situation? Should I close all FD before daemonizing or just forget it? Any other hints? Kind regards, Depends. For *NIX systems, it's a good idea to use the syslog daemon for logging where it's available. I believe the logging module can be configured to log to the local syslog daemon. Cheers. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python suitable for Midi ?
Derek Martin [EMAIL PROTECTED] writes: On Tue, Oct 28, 2008 at 06:54:57PM +0200, Chuckk Hubbard wrote: The problem I've run into is that I can't set the audio to a higher priority than the GUI (Tkinter). If I move the mouse over the app, no matter what, I get audio dropouts. AFAICT this is the same for all Python, regardless of what modules one uses: you can't assign system priorities to different threads. If you're planning to pipe MIDI to another app for playback, maybe it won't be an issue for you. FWIW... You could take your own advice, and devide your application in two: one process manages the GUI, and the second is a back-end process that plays the MIDI. Your GUI can even launch the back end, which will inherit the priority of the GUI, after which the GUI can reduce its own priority (the priority of the back end will not be affected by the change)... -- Derek D. Martin http://www.pizzashack.org/ GPG Key ID: 0x81CFE75D One also has access to nice-levels on unix systems. -- http://mail.python.org/mailman/listinfo/python-list
Re: python extensions: including project local headers
Philip Semanchuk [EMAIL PROTECTED] writes: On Oct 23, 2008, at 3:18 PM, J Kenneth King wrote: Philip Semanchuk [EMAIL PROTECTED] writes: On Oct 23, 2008, at 11:36 AM, J Kenneth King wrote: Hey everyone, I'm working on a python extension wrapper around Rob Hess' implementation of a SIFT feature detector. I'm working on a computer-vision based project that requires interfacing with Python at the higher layers, so I figured the best way to handle this would be in C (since my initial implementation in python was ungodly and slow). I can get distutils to compile the extension and install it in the python path, but when I go to import it I get the wonderful exception: ImportError: /usr/lib/python2.5/site-packages/pysift.so: undefined symbol: _sift_features Kenneth, You're close but not interpreting the error quite correctly. This isn't an error from the compiler or preprocessor, it's a library error. Assuming this is dynamically linked, your OS is reporting that, at runtime, it can't find the library that contains _sift_features. Make sure that it's somewhere where your OS can find it. This is basically what I was looking for help with. So far the project directory is: /pysift /sift .. /include .. sift.h /src .. sift.c /src pysift.c setup.py I thought I could just #include sift.h in pysift.c as long as distutils passed the right -I path to gcc. That's true, and it sounds like you've got that part working. Maybe I should compile the sift code as a shared object and link it to my extension? How would I get distutils to build the makefile and tell gcc how to link it? Thanks for the reply. Python has spoiled me and my C is rather rusty. :) I don't know how to get setup.py to build a shared object separately. I am in the same Python/C situation as you. I'm scrubbing the rust off of my C skills and I'm also a n00b at developing extensions. I've learned a lot from looking at other people's setup code, so maybe I can help you there. My posix_ipc module links to the realtime lib rt and here's the relevant snippets of setup.py: -- import distutils.core as duc libraries = [ ] libraries.append(rt) source_files = [posix_ipc_module.c] ext_modules = [ duc.Extension(posix_ipc, source_files, define_macros=define_macros, libraries=libraries ) ] duc.setup(name=posix_ipc, version=VERSION, ext_modules=ext_modules) -- You can download the whole thing here if you want to examine all the code: http://semanchuk.com/philip/posix_ipc/ HTH Philip I'll take a look, thanks! :) -- http://mail.python.org/mailman/listinfo/python-list
python extensions: including project local headers
Hey everyone,
I'm working on a python extension wrapper around Rob Hess'
implementation of a SIFT feature detector. I'm working on a
computer-vision based project that requires interfacing with Python at
the higher layers, so I figured the best way to handle this would be in
C (since my initial implementation in python was ungodly and slow).
I can get distutils to compile the extension and install it in the
python path, but when I go to import it I get the wonderful exception:
ImportError: /usr/lib/python2.5/site-packages/pysift.so: undefined
symbol: _sift_features
Of course, _sift_features is a function defined in his header that I'm
#including in my extension.
His sources are sitting in my project root under sift/ while my source
is under src/ -- My setup.py is as follows:
[code]
from distutils.core import setup, Extension
pysift = Extension('pysift',
include_dirs = ['sift/include'],
sources = ['src/pysift.c'],
extra_link_args = ['-lm', '-lcv', '-lcxcore',
'-lhighgui', '-lcvaux'])
setup(name = 'pysift',
version = '0.0',
description = 'A SIFT feature detection package',
author = 'James Kenneth King',
author_email = [EMAIL PROTECTED],
url = http://agentultra.com/;,
long_description =
A python extension package for detecting SIFT
features using Rob Hess' C implementation.
http://web.engr.oregonstate.edu/~hess/
Original SIFT feature descriptors by David Lowe
and patented by the University of British Columbia.
,
ext_modules = [pysift])
[/code]
And the include to Rob's header file is on the second line of pysift.c:
#include sift.h
The weird thing (to me in my somewhat hackish knowledge of C) is that I
can use all the #defines from sift.h with no complaints from the
preprocessor (in fact, there are no complaints at all from the compiler
when compiling the extension module).
Once I get this bugger working, I'll be setting up a project page to
share sources and will also be releasing extension wrappers to the
OpenCV libraries.
I've never released any code before so any help getting this right and
proper for the community would be greatly appreciated.
Cheers.
--
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Re: python extensions: including project local headers
Robert Kern [EMAIL PROTECTED] writes:
Philip Semanchuk wrote:
On Oct 23, 2008, at 11:36 AM, J Kenneth King wrote:
Hey everyone,
I'm working on a python extension wrapper around Rob Hess'
implementation of a SIFT feature detector. I'm working on a
computer-vision based project that requires interfacing with Python at
the higher layers, so I figured the best way to handle this would be in
C (since my initial implementation in python was ungodly and slow).
I can get distutils to compile the extension and install it in the
python path, but when I go to import it I get the wonderful exception:
ImportError: /usr/lib/python2.5/site-packages/pysift.so: undefined
symbol: _sift_features
Kenneth,
You're close but not interpreting the error quite correctly. This
isn't an error from the compiler or preprocessor, it's a library
error. Assuming this is dynamically linked, your OS is reporting
that, at runtime, it can't find the library that contains
_sift_features. Make sure that it's somewhere where your OS can find
it.
It looks like the library implementing it was not linked into the
extension. sift_features() is not part of OpenCV.
James, are you including the source of Rob Hess's implementation with
your extension, or are you trying to link against an already installed
version of the library? If the former, you need to add the C sources
to the pysift Extension(). If the latter, you need to add the name of
the library to the list of libraries.
I'm including Rob Hess' sources with the extension.
Would that mean I should add library_dirs to Extension() to point to the
sources in the project's path?
Also, you don't want to pass the list of libraries with
extra_link_args. Instead, use libraries=.
pysift = Extension('pysift',
include_dirs = ['sift/include'],
sources = ['src/pysift.c'],
libraries = ['feat', 'cv', 'cxcore', 'highgui',
'cvaux', 'm'])
Thanks for taking a moment to help me out. :)
--
http://mail.python.org/mailman/listinfo/python-list
Re: python extensions: including project local headers
Philip Semanchuk [EMAIL PROTECTED] writes: On Oct 23, 2008, at 11:36 AM, J Kenneth King wrote: Hey everyone, I'm working on a python extension wrapper around Rob Hess' implementation of a SIFT feature detector. I'm working on a computer-vision based project that requires interfacing with Python at the higher layers, so I figured the best way to handle this would be in C (since my initial implementation in python was ungodly and slow). I can get distutils to compile the extension and install it in the python path, but when I go to import it I get the wonderful exception: ImportError: /usr/lib/python2.5/site-packages/pysift.so: undefined symbol: _sift_features Kenneth, You're close but not interpreting the error quite correctly. This isn't an error from the compiler or preprocessor, it's a library error. Assuming this is dynamically linked, your OS is reporting that, at runtime, it can't find the library that contains _sift_features. Make sure that it's somewhere where your OS can find it. This is basically what I was looking for help with. So far the project directory is: /pysift /sift .. /include .. sift.h /src .. sift.c /src pysift.c setup.py I thought I could just #include sift.h in pysift.c as long as distutils passed the right -I path to gcc. Maybe I should compile the sift code as a shared object and link it to my extension? How would I get distutils to build the makefile and tell gcc how to link it? Thanks for the reply. Python has spoiled me and my C is rather rusty. :) -- http://mail.python.org/mailman/listinfo/python-list
Re: PYTHON WORKING WITH PERL ??
Pat [EMAIL PROTECTED] writes: Sean DiZazzo wrote: On Sep 29, 12:44 pm, Blubaugh, David A. [EMAIL PROTECTED] wrote: Sir, You are absolutely correct. I was praying to G_d I did not have to slaughter my project's source code in this manner. However, like life itself, I was given legacy source code (i.e. someone else errors to fix) in Perl. However, I have just found out that there is a way to import the Perl interpreter within Python!!! I now believe I can utilize python as the main platform to develop the project upon !! Thanks, David -Original Message- From: D'Arcy J.M. Cain [mailto:[EMAIL PROTECTED] Sent: Monday, September 29, 2008 1:32 PM To: Blubaugh, David A. Cc: [EMAIL PROTECTED] Subject: Re: PYTHON WORKING WITH PERL ?? On Mon, 29 Sep 2008 13:16:14 -0400 Blubaugh, David A. [EMAIL PROTECTED] wrote: I was wondering if it was possible to have a situation where a programming project would utilized BOTH python and perl? Such as utilizing python for internet programming and then utilize perl for text processing and systems programming? Is this even feasible??? I don't see why not but I also question if it is a good idea. Once you have all your objects and low level methods written in Python it just makes sense to re-use them rather than trying to duplicate the functionality in another language. Of course, sometimes we don't have control over our entire environment so yes, you can mix them if you have to. Rewrite everything in python. Save yourself now...while you still can. ~Sean Trust me. Sean is absolutely correct. I'm currently in the process of converting a large Perl project to Python (and learning Python at the same time) and the improvement in code is incredible. After you learn Python, you'll come to despise Perl. Depends on the person -- I still love Perl, but program in Python every day at work. Python is great, but don't be mistaken: it's not the one language to rule them all. No language is (except maybe Lisp). But yay for converting a project to python. :) -- http://mail.python.org/mailman/listinfo/python-list
Re: PYTHON WORKING WITH PERL ??
Joshua Kugler [EMAIL PROTECTED] writes: Pat wrote: Rewrite everything in python. Save yourself now...while you still can. ~Sean Trust me. Sean is absolutely correct. I'm currently in the process of converting a large Perl project to Python (and learning Python at the same time) and the improvement in code is incredible. After you learn Python, you'll come to despise Perl. I'm not a Python fan-boy, but I'm going to have to agree with Sean too. I had been using Perl on-and-off for some 10 years, when I finally had to write a 500-ish line script in Perl for some data processing. It got messy in a hurry. Is this a hash? Is it a reference to a hash? Is it a reference to a hash of array references? Gaaah! I rewrote it in Python, and it was so much easier to keep all my data structures straight. j Perl just gives you a lot of rope. You can do a lot of neat things with rope. ;) -- http://mail.python.org/mailman/listinfo/python-list
Re: PIL problem
bfrederi [EMAIL PROTECTED] writes: I am having a problem using PIL. I am trying to crop and image to a square, starting from the center of the image, but when I try to crop the image, it won't crop. Here are the relevant code snippets: ### Function I am testing ### def create_square_image(file_name): Creates a thumbnail sized image and turns it into a square image = Image.open(open(file_name)) size_tuple = image.size width = size_tuple[0] height = size_tuple[1] square_length = 75 x1 = (width / 2) - (square_length / 2) x2 = x1 + square_length y1 = (height / 2) - (square_length / 2) y2 = y1 + square_length image.crop((x1,y1,x2,y2)) image.save(file_name, JPEG) def create_square_image(filename, size=75): file = open(filename, 'rb') image = Image.open(file) w, h = image.size x1 = (w / 2) - (size / 2) x2 = x1 + size y1 = (h / 2) - (size / 2) y2 = y1 + size thumb = image.crop((x1,y1,x2,y2)) thumb.save(thumb_ + filename, JPEG) ... of course PIL has a thumbnail method that does this type of stuff. -- http://mail.python.org/mailman/listinfo/python-list
