Re: slicing, mapping types, ellipsis etc.
Nick Coghlan wrote: Jerry Sievers wrote: Fellow Pythonists; I am totally puzzled on the use of slicing on mapping types and It's generally not supported (since slices are designed to work with the numerical indices of a sequence, not the arbitrary keys of a mapping). Section 5.3.3 of the Language Reference seems to say that with extended slicing, the slice elements are used to create a key that indexes a mapping. "The semantics for an extended slicing are as follows. The primary must evaluate to a mapping object, and it is indexed with a key that is constructed from the slice list, as follows." From my understanding of this thread so far, extended slicing is used as a form of indexing in Numeric. Are Numeric arrays considered mappings? Or is this paragraph in 5.3.3 off the mark? Maybe instead of referring to mappings it should say "The primary must implement __getitem__(), which is called with a value that is constructed from the slice list, as follows." Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: slicing, mapping types, ellipsis etc.
Nick Coghlan wrote: Kent Johnson wrote: Maybe instead of referring to mappings it should say "The primary must implement __getitem__(), which is called with a value that is constructed from the slice list, as follows." In the section you mention, 'mapping' is equivalent to 'has __getitem__ defined', and I'd be surprised if it's an isolated usage. Python actually has trouble distinguishing between sequences and mappings, as anyone who as tried to use the 'isMapping' API would know (the isMapping API uses much the same definition as the reference manual does - so all sequences show up as mappings, as they map indices and slices to objects). Section 3 of the reference manual is actually more use for anyone developing custom types that override special methods. E.g. proper handling of slice objects is described here under container emulation: http://www.python.org/dev/doc/devel/ref/sequence-types.html I understand that the distinction between sequences and mappings is fuzzy, as both use __getitem__() for access. But the usage of 'mapping' in 5.3.3 is inconsistent with the section you refer to. That page says "It is also recommended that mappings provide the methods keys(), values(), items(), has_key(), get(), clear(), setdefault(), iterkeys(), itervalues(), iteritems(), pop(), popitem(), copy(), and update() behaving similar to those for Python's standard dictionary objects." and under __getitem__(): "For *sequence* types, the accepted keys should be integers and slice objects." I just think 5.3.3 is unnecessarily opaque. Particularly since the only built-in mapping (dict) doesn't even accept simple slices as indices. Kent Regards, Nick. -- http://mail.python.org/mailman/listinfo/python-list
Re: access to generator state
Neal D. Becker wrote: Only one problem. Is there any way to access the state of a generator externally? In other words, the generator saves all it's local variables. Can an unrelated object then query the values of those variables? (In this case, to get at intermediate results) You could make the generator a method of a class and store the generator state in instance variables instead of local variables: >>> class Gen: ... def __init__(self): ... self.i = 0 ... def __call__(self): ... while True: ... yield self.i ... self.i += 1 ... >>> g=Gen() >>> g.i 0 >>> iter=g() >>> iter.next() 0 >>> g.i 0 >>> iter.next() 1 >>> g.i 1 HTH Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: PySQLLite Speed
Kevin wrote:
Hello All,
I wanted to thank Roger Binn for his email. He had
the answer to my issue with writing speed. It's
actual made an incredible change in the preformace. I
didn't have to go all the way to implementing the
synchronous mode(for my app). Previously, I was
insert one record at a time. The key was to write
them all at one time. I moved up to a 13 meg file and
wrote it to the db in secs. Now the issue is the 120
meg of RAM consumed by PyParse to read in a 13 meg
file. If anyone has thoughts on that, it would be
great. Otherwise, I will repost under a more specific
email.
If your data is (or can be) created by an iterator, you can use this recipe to group the data into
batches of whatever size you choose and write the individual batches to the db.
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/303279
Kent
Thanks,
Kevin
db.execute("begin")
while i < TriNum
db.execute("""insert into TABLE(V1_x)
values(%f),""" (data[i]))
i = i + 1
db.execute("commit")
__
Do you Yahoo!?
Yahoo! Mail - You care about security. So do we.
http://promotions.yahoo.com/new_mail
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Refactoring a generator function
Here is a simple function that scans through an input file and groups the lines of the file into sections. Sections start with 'Name:' and end with a blank line. The function yields sections as they are found. def makeSections(f): currSection = [] for line in f: line = line.strip() if line == 'Name:': # Start of a new section if currSection: yield currSection currSection = [] currSection.append(line) elif not line: # Blank line ends a section if currSection: yield currSection currSection = [] else: # Accumulate into a section currSection.append(line) # Yield the last section if currSection: yield currSection There is some obvious code duplication in the function - this bit is repeated 2.67 times ;-): if currSection: yield currSection currSection = [] As a firm believer in Once and Only Once, I would like to factor this out into a separate function, either a nested function of makeSections(), or as a separate method of a class implementation. Something like this: def makeSections(f):### DOESN'T WORK ### currSection = [] def yieldSection(): if currSection: yield currSection del currSection[:] for line in f: line = line.strip() if line == 'Name:': # Start of a new section yieldSection() currSection.append(line) elif not line: # Blank line ends a section yieldSection() else: # Accumulate into a section currSection.append(line) # Yield the last section yieldSection() The problem is that yieldSection() now is the generator, and makeSections() is not, and the result of calling yieldSection() is a new iterator, not the section... Is there a way to do this or do I have to live with the duplication? Thanks, Kent Here is a complete program: data = ''' Name: City: Name: City: ''' import cStringIO# just for test def makeSections(f): ''' This is a generator function. It will return successive sections of f until EOF. Sections are every line from a 'Name:' line to the first blank line. Sections are returned as a list of lines with line endings stripped. ''' currSection = [] for line in f: line = line.strip() if line == 'Name:': # Start of a new section if currSection: yield currSection currSection = [] currSection.append(line) elif not line: # Blank line ends a section if currSection: yield currSection currSection = [] else: # Accumulate into a section currSection.append(line) # Yield the last section if currSection: yield currSection f = cStringIO.StringIO(data) for section in makeSections(f): print 'Section' for line in section: print ' ', line print -- http://mail.python.org/mailman/listinfo/python-list
Re: about python advanced/new features documentation
Kl wrote: Hi, python is really easy to learn in my opinion. There are loads of tutorials/books on the web talking about the most common python features. The problem comes when they add something new to the language or you want to use advanced features. Since python is still evolving its difficult to find good documentation on these new features/language changes. Where can i find always up-to-date documentation about python? Unfortunately the official tutorial and books become obsolete really fast. The "What's New" documents that are bundled with the last several Python releases are very helpful. They link to the PEPs which generally give a lot of detail about a change. Quite a few recipes were contributed to the online Python Cookbook demonstrating Python 2.4 features. Kent Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: string slicing
Ishwor wrote:
s = 'hello'
m = s[:]
m is s
True
I discussed the *is* operator with some of the pythoners before as
well but it is somewhat different than what i intended it to do. The
LP2E by Mark & David says -
" m gets a *full top-level copy* of a sequence object- an object with
the same value but distinct piece of memory." but when i test them
with *is* operator then the result is True. Why is this happening??
This behaviour is due to the way strings are handled. In some cases strings are 'interned' which
lets the interpreter keep only a single copy of a string. If you try it with a list you get a
different result:
>>> s=list('hello')
>>> s
['h', 'e', 'l', 'l', 'o']
>>> m=s[:]
>>> m
['h', 'e', 'l', 'l', 'o']
>>> m is s
False
Kent
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Re: string slicing
Ishwor wrote: On Sun, 05 Dec 2004 09:44:13 -0500, Kent Johnson <[EMAIL PROTECTED]> wrote: This behaviour is due to the way strings are handled. In some cases strings are 'interned' which lets the interpreter keep only a single copy of a string. If you try it with a list you get a different result Thanx Kent. so for lists Python doesn't keep the same object in the cache??? Right, AFAIK lists are not cached in this way. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Import a module without executing it?
Jay O'Connor wrote: The real question, I suppose, is "what is a good technique to find what modules and classes implement or refer to particular names" You might like to try ctags. I have had a good experience with it. It's not as automatic as I would like - you have to build a cross-reference table before you can use it - and it only finds implementors, not referrers. It integrates with lots of editors, I have used it with TextPad. http://ctags.sourceforge.net/ Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Import a module without executing it?
Andy, this is a nice example. It prompted me to look at the docs for compiler.visitor. The docs are,
um, pretty bad. I'm going to attempt to clean them up a little. Would you mind if I include this
example?
Thanks,
Kent
Andy Gross wrote:
Here's a quick example that will pull out all functions defined in the
top-level of a module:
---
#/usr/bin/env python
from compiler import parse, walk
from compiler.visitor import ASTVisitor
testdata = r'''
def aFunction(anArg):
return anArg + 1
'''
class SimpleVisitor(ASTVisitor):
def visitFunction(self, parsedFunc):
print "Function %(name)s at %(lineno)s takes %(argnames)s " \
" with code %(code)s" % parsedFunc.__dict__
if __name__ == "__main__":
ast = parse(testdata)
walk(ast, SimpleVisitor(), verbose=True)
---
[EMAIL PROTECTED]:~$ ./test.py
Function aFunction at 2 takes ['anArg'] with code
Stmt([Return(Add((Name('anArg'), Const(1])
HTH,
/arg
On Dec 7, 2004, at 11:14 PM, Caleb Hattingh wrote:
Andy
thx for that. I had a file called 'tktest.py' lying around, and I did:
'>>> a = compiler.parseFile('tktest.py')
And "a" looks something like this:
***
Stmt([Import([('Tkinter', None)]), Function(None, 'add_rows', ['w',
'titles', 'rows'], [], 0, None,
Stmt([Discard(CallFunc(Getattr(Name('w'), 'configure'),
[Keyword('state', Const('normal'))], None, None)), For(AssName('r',
'OP_ASSIGN'), Name('rows'), Stmt([For(AssTuple([AssName('t',
'OP_ASSIGN'), AssName('v', 'OP_ASSIGN')]), CallFunc(Name('zip'),
[Name('titles'), Name('r')], None, None),
Stmt([Discard(CallFunc(Getattr(Name('w'), 'insert'), [Const('end'),
Mod((Const('%s:\t%s\n'), Tuple([Name('t'), Name('v')])))], None,
None))]), None), Discard(CallFunc(Getattr(Name('w'), 'insert'),
[Const('end'), Const('\n')], None, None))]), None),
Discard(CallFunc(Getattr(Name('w'), 'configure'), [Keyword('state',
Const('disabled'))], None, None))])), Assign([AssName('app',
'OP_ASSIGN')], CallFunc(Getattr(Name('Tkinter'), 'Tk'), [], None,
None)), Assign([AssName('t', 'OP_ASSIGN')],
CallFunc(Getattr(Name('Tkinter'), 'Text'), [Name('app'),
Keyword('state', Const('disabled'))], None, None)),
Discard(CallFunc(Getattr(Name('t'), 'pack'), [], None, None)),
Assign([AssName('info', 'OP_ASSIGN')], List([List([Const('Ali'),
Const(18)]), List([Const('Zainab'), Const(16)]),
List([Const('Khalid'), Const(18)])])),
Discard(CallFunc(Name('add_rows'), [Name('t'), List([Const('Name'),
Const('Age')]), Name('info')], None, None)),
Discard(CallFunc(Getattr(Name('app'), 'mainloop'), [], None, None))])
***
Pretty impressive :)
Do you know of more batteries that can process this stuff further, for
interest sake (and maybe the OP)?
thx again
Caleb
On Tue, 7 Dec 2004 15:57:16 -0500, Andy Gross <[EMAIL PROTECTED]> wrote:
You'll want to use the "compiler" package. compiler.parseFile will
return an AST that you can inspect (which is not really 'reflection',
btw).
/arg
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Re: converting html escape sequences to unicode characters
harrelson wrote: I have a list of about 2500 html escape sequences (decimal) that I need to convert to utf-8. Stuff like: 비 행 기 로 보 낼 거 에 요 내 면 금 이 얼 마 지 잠 Anyone know what the decimal is representing? It doesn't seem to equate to a unicode codepoint... In well-formed HTML (!) these should be the decimal values of Unicode characters. See http://www.w3.org/TR/html4/charset.html#h-5.3.1 These characters appear to be Hangul Syllables: http://www.unicode.org/charts/PDF/UAC00.pdf import unicodedata nums = [ 48708, 54665, 44592, 47196, 48372, 45244, 44144, 50640, 50836, 45236, 47732, 44552, 51060, 50620, 47560, 51648, 51104, ] for num in nums: print num, unicodedata.name(unichr(num), 'Unknown') => 48708 HANGUL SYLLABLE BI 54665 HANGUL SYLLABLE HAENG 44592 HANGUL SYLLABLE GI 47196 HANGUL SYLLABLE RO 48372 HANGUL SYLLABLE BO 45244 HANGUL SYLLABLE NAEL 44144 HANGUL SYLLABLE GEO 50640 HANGUL SYLLABLE E 50836 HANGUL SYLLABLE YO 45236 HANGUL SYLLABLE NAE 47732 HANGUL SYLLABLE MYEON 44552 HANGUL SYLLABLE GEUM 51060 HANGUL SYLLABLE I 50620 HANGUL SYLLABLE EOL 47560 HANGUL SYLLABLE MA 51648 HANGUL SYLLABLE JI 51104 HANGUL SYLLABLE JAM Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: gather information from various files efficiently
Keith Dart wrote: try: dict[a].append(b) except KeyError: dict[a] = [b] or my favorite Python shortcut: dict.setdefault(a, []).append(b) Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: ".>>>" is a good idea! (OT, was: Re: do you master list comprehensions?)
Keith Dart wrote: What I do is set Python's sys.ps1 variable to something else. I have a module called "interactive" that I import implicitly by shell alias: py='python -i -c '\''import interactive'\' Which, among other things, sets the prompt to "Python> " You can do the same thing using a PYTHONSTARTUP file - see http://docs.python.org/tut/node4.html#SECTION00424 You can change the prompts with import sys sys.ps1 = ' >>> ' sys.ps2 = ' ... ' Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: getopt: Make argument mandatory
Frans Englich wrote: On Wednesday 15 December 2004 14:07, Diez B. Roggisch wrote: In my use of getopt.getopt, I would like to make a certain parameter mandatory. I know how to specify such that a parameter must have a value if it's specified, but I also want to make the parameter itself mandatory(combined with a mandatory value, the result is that the user must specify a value). Use optparse - in the examples section you'll find what you need. I'm slow here, do you mean in of the callback examples in 6.21.4? http://docs.python.org/lib/module-optparse.html No, try here - this section seems to have been deleted from the Python 2.4 docs! http://www.python.org/doc/2.3.4/lib/optparse-extending-examples.html Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: ".>>>" is a good idea! (OT, was: Re: do you master list comprehensions?)
Steven Bethard wrote: Very cool. I didn't know about this. Does anyone know how to make it work with Pythonwin[1]? (Obviously, I can type the above in manually every time, but I'd much rather have Pythonwin do this automatically for me.) Steve [1] I'd do my example code at the command prompt, but I can't live without copy-paste. ;) You can copy and paste from a Windows command prompt. It's a bit bizarre, but - In the system menu for a command window, pick Properties - On the Options tab, turn on Quick Edit mode - Now you can copy and paste with right-click (!). If you have text selected, right-click will copy, otherwise paste. It's a bit strange but it works. I think it's wonderfully ironic that in Windows - which takes such pains to make everything keyboard accessible - in a *command line* window, which is using keyboard input by its nature - you have to use the mouse for copy and paste!! Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Wrapper objects
Nick Coghlan wrote: Simon Brunning wrote: This work - <http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52295>? Only for old-style classes, though. If you inherit from object or another builtin, that recipe fails. Could you explain, please? I thought __getattr__ worked the same with new- and old-style classes? Thanks, Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: How do I convert characters into integers?
Markus Zeindl wrote: I have got a string from the user, for example "Hi!". Now I get every character with a loop: buffer = "" for i in range(len(message)): ch = message[i-1:i] for ch in message: ... is simpler and more idiomatic. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Jython performance
Sean Blakey wrote: On Wed, 22 Dec 2004 17:03:55 -0200, Gabriel Cosentino de Barros <[EMAIL PROTECTED]> wrote: On the "Best GUI for small-scale accounting app?" tread some people mentioned jython. I went to read about it, but i was wondering if anyone has any real project done with it and can give real world comments about performance. I've been very happy with it's performance, after the one-time interpreter startup. That matches my experience as well. I have written a medium-sized GUI app using Jython and Swing and I am very happy with the performance. Most of the heavy lifting is done in Java libraries anyway - primarily Swing, dom4j and Velocity in my case. The initial import of a module is relatively slow and I often defer importing a module until it is needed. Other than that I have been pleased with the performance. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: mathmatical expressions evaluation
Tonino wrote: thanks all for the info - and yes - speed is not really an issue and no - it is not an implementation of a complete financial system - but rather a small subset of a investment portfolio management system developed by "another company" ... What I am trying to achieve is to parse a formula(s) and generate a result ... Why do you need to parse the formulas at runtime? It sounds like they are known in advance and you could just write functions to implement the calculations. Kent I will look into the pyparsing suggested and maybe even leave out numarrays for now - as it seems a bit overkill ... The formula are a bit complex and maybe even difficult to write out Thanks all - I will post my progress ;) -- http://mail.python.org/mailman/listinfo/python-list
Re: Lambda going out of fashion
Robin Becker wrote: Alex Martelli wrote: . By the way, if that's very important to you, you might enjoy Mozart (http://www.mozart-oz.org/) .very interesting, but it wants to make me install emacs. :( Apparently you can also use oz with a compiler and runtime engine...see http://www.mozart-oz.org/documentation/apptut/index.html Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Jython & IronPython Under Active Development?
Steve Holden wrote: Just a little further background. The Python Software Foundation recently awarded a grant to help to bring Jython into line with the current CPython release. Is information publicly available about this and other PSF grants? I don't see any announcement on the PSF web site or in the grants-discuss mail list. Thanks, Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: The Industry choice
Alex Martelli wrote: Roy Smith <[EMAIL PROTECTED]> wrote: Stefan Axelsson <[EMAIL PROTECTED]> wrote: Yes, ignoring most of the debate about static vs. dynamic typing, I've also longed for 'use strict'. You can use __slots__ to get the effect you're after. Well, sort of; it only works for instance variables, not locals. And the gurus will argue that __slots__ wasn't intended for that, so you shouldn't do it. There's a simple, excellent recipe by Michele Simionato, on both the online and forthcoming 2nd edition printed Cookbook, showing how to do that the right way -- with __setattr__ -- rather than with __slots__ . The recipe is here (it took me a few minutes to find it, I found the title misleading): http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/252158 Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter: passing parameters to menu commands
Philippe C. Martin wrote:
I have many menu items and would like them all to call the same method
-However, I need the method called to react differently depending on the
menu item selected. Since the menu command functions do not seem to
receive any type of event style object, is there some type of Tkinter
call that would let my method know the menu id selected ?
Much as it seems to be out of favor, IMO this is a place where a lambda expression is very handy.
You can make a callback for each menu item that binds an extra parameter to the handler:
# Based on an example by Fredrik Lundh
from Tkinter import *
def callback(code):
print "called the callback with code", code
root = Tk()
# create a menu
menu = Menu(root)
root.config(menu=menu)
filemenu = Menu(menu)
menu.add_cascade(label="File", menu=filemenu)
filemenu.add_command(label="New", command=lambda: callback('New'))
filemenu.add_command(label="Open...", command=lambda: callback('Open'))
filemenu.add_separator()
filemenu.add_command(label="Exit", command=lambda: callback('Exit'))
mainloop()
Of course you could do this with named forwarding functions if you prefer.
Kent
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Re: Tkinter: passing parameters to menu commands
Philippe C. Martin wrote:
menu.add_cascade(label="File", menu=filemenu)
filemenu.add_command(label="New", command=lambda: callback('New'))
filemenu.add_command(label="Open...", command=lambda:
Of course you could do this with named forwarding functions if you
prefer
I'm not sure what 'named forwarding functions'
Bad choice of terminology, I just mean you can explicitly define
def handleNew:
callback('New')
etc.
are but I'm actually in a
class and when applying your suggestion in the following manner,
everything works (THANKS!)
def __Dec(self,p_string):
for i in p_string:
self.__Insert(i)
.
.
.
#menu creation
l_dec.add_command(label = 'ATR', command=lambda: self.__Dec('ATR'))
l_dec.add_command(label = 'IN', command=lambda:self.__Dec('IN'))
.
.
.
Yet I have a question:
If I replace the menu creation code as below, and since __Insert appends
the string p_string into a text widget that is created _after_ the menu
creation; the method __Dec seems to be called at the menu creation and
I get an error in __Insert because the test widget is equal to None.
My reflexes of C programmer tell me that command=self.__Dec just
passes a method pointer (sorry I said it) to add_command - yet it does
not seem to be so.
>
> What is actually going on ?
>
>
> #menu creation
> l_dec.add_command(label = 'ATR', command=self.__Dec('ATR'))
> l_dec.add_command(label = 'IN', command=self.__Dec('IN'))
self.__Dec is a reference to the function. It is similar to a method pointer so you don't need to
apologize ;) The name of a function without the () is a reference. When you append () it becomes a
call to the referenced function.
The command parameter for the menu must be a reference to a function. The function is called with no
arguments when the menu is invoked.
So, you need a function of no arguments to handle the command. For example,
def handleMenu():
print 'Handled'
filemenu.add_command(label="New", command=handleMenu)
Note there is no () after handleMenu. 'command' is bound to the function object; the function is not
called until later.
OK, now suppose you want to pass a parameter to handleMenu?
def handleMenu(menuName):
print 'Handled', menuName
Now what do you put in the command parameter? This won't work because you are *calling* handleMenu
and assigning the result of the call (in this case the value None) to 'command':
filemenu.add_command(label="New", command=handleMenu('New')) # WRONG
You need a new function of zero arguments to bind to 'command'. Here is one way
to do it:
def handleNew():
handleMenu('New')
filemenu.add_command(label="New", command=handleNew) # OK
Note, again, no () after handleNew. 'command' is bound to the function object
again.
OK, what about lambda? lambda is a way to create a simple anonymous function. One simple use of
lambda is to make a new function that binds a parameter to another function.
lambda: handleMenu('New')
defines a function that does the same thing as handleNew. The value of the lambda expression is the
function object. So
filemenu.add_command(label="New", command=lambda: handleMenu('New')) # OK
is another way to get the result you want.
Kent
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Re: Speed revisited
Andrea Griffini wrote: I've to admit that I also found strange that deleting the first element from a list is not O(1) in python. My wild guess was that the extra addition and normalization required to have insertion in amortized O(1) and deletion in O(1) at both ends of a random access sequence was going to have basically a negligible cost for normal access (given the overhead that is already present in python). This was added to Python 2.4 as collections.deque Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Please Contribute Python Documentation!
Aahz wrote: In article <[EMAIL PROTECTED]>, Tony Meyer <[EMAIL PROTECTED]> wrote: I don't think I've seen such a statement before - the stuff I've seen all indicates that one should be submitting proper LaTeX docs/patches. If plain-text contributions are welcome, could this be added to the doc about contributing to the docs? (I suppose I could submit a patch, but that seems overkill ). It *is* in the docs now -- see the top of http://www.python.org/doc/2.4/doc/doc.html It's also spelled out pretty clearly in the "About this document" document you get by clicking on the link at the bottom of every page. Kent (This has been the official policy for some time, but you're right that it wasn't earlier documented. So I filed a bug report. ;-) If you think this still isn't enough, file another.) -- http://mail.python.org/mailman/listinfo/python-list
Re: Python & unicode
[EMAIL PROTECTED] wrote: I forgot to add the following: setattr(C, "Ã", u"The letter Ã") getattr(C, "Ã") u'The letter \xe8' print getattr(C, "Ã") The letter à But try this: >>> C.à File "", line 1 C.â ^ SyntaxError: invalid syntax Python identifiers can be generic strings, including Latin-1 characters; I don't think so. You have hacked an attribute with latin-1 characters in it, but you haven't actually created an identifier. According to the language reference, identifiers can only contain letters a-z and A-Z, digits 0-9 and underscore. http://docs.python.org/ref/identifiers.html Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: [csv module] duplication of end of line character in output file generated
simon.alexandre wrote:
Hi all,
I use csv module included in python 2.3. I use the writer and encouter the
following problem: in my output file (.csv) there is a duplication of the
end of line character, so when I open the csv file in Ms-Excel a blank line
is inserted between each data line.
From the docs for csv.writer():
writer( csvfile[, dialect='excel'[, fmtparam]])
...If csvfile is a file object, it must be opened with the 'b' flag on platforms where that
makes a difference.
Windows is a "platform where that makes a difference." So try
self.writer = csv.writer(file("Test.csv", "wb"))
Kent
OS: W2k
Someone has an idea ?
thanks in advance
the source code is the following:
-->
import csv
class CsvDumper:
def __init__(self):
self.object =
[['la','mb','mc','md'],['ma','mb','mc','md'],['ma','mb','mc','md']]
self.writer = csv.writer(file("Test.csv", "w"))
def DumpCsvFile(self):
for row in self.object:
self.writer.writerow(row)
c = CsvDumper()
c.DumpCsvFile()
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Re: Python & unicode
[EMAIL PROTECTED] wrote: Kent: I don't think so. You have hacked an attribute with latin-1 characters in it, but you haven't actually created an identifier. No, I really created an identifier. For instance I can create a global name in this way: globals()["è"]=1 globals()["è"] 1 Maybe I'm splitting hairs but to me an identifier is a syntactical element that can be used in specific ways. For example the syntax defines attributeref ::= primary "." identifier so if identifiers can contain latin-1 characters you should be able to say C.è=1 Kent According to the language reference, identifiers can only contain letters a-z and A-Z, digits 0-9 and underscore. http://docs.python.org/ref/identifiers.html The parser has this restriction, so it gets confused if it finds "è". But the underlying implementation just works for generic identifiers. Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
iTools
Where can I download python-itools? I found it in the python packages index but the site is not contactable. Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: xml parsing escape characters
Luis P. Mendes wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 this is the xml document: http://www..";><DataSet> ~ <Order> ~ <Customer>439</Customer> (... others ...) ~ </Order> </DataSet> This is an XML document containing a single tag, , whose content is text containing entity-escaped XML. This is *not* an XML document containing tags , , , etc. All the behaviour you are seeing is a consequence of this. You need to unescape the contents of the tag to be able to treat it as structured XML. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: xml parsing escape characters
Irmen de Jong wrote: Kent Johnson wrote: [...] This is an XML document containing a single tag, , whose content is text containing entity-escaped XML. This is *not* an XML document containing tags , , , etc. All the behaviour you are seeing is a consequence of this. You need to unescape the contents of the tag to be able to treat it as structured XML. The unescaping is usually done for you by the xml parser that you use. Yes, so if your XML contains for example <not a tag> and you parse this and ask for the *text* content of the tag, you will get the string "" but it's still *not* a tag. If you try to get child elements of the element there will be none. This is exactly the confusion the OP has. --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: Overloading ctor doesn't work?
Martin Häcker wrote: Hi there, I just tried to run this code and failed miserably - though I dunno why. Could any of you please enlighten me why this doesn't work? Here is a simpler test case. I'm mystified too: from datetime import datetime class time (datetime): def __init__(self, hours=0, minutes=0, seconds=0, microseconds=0): datetime.__init__(self, 2001, 10, 31, hours, minutes, seconds, microseconds) print time(1,2,3,4) # => 0001-02-03 04:00:00 print time()# => TypeError: function takes at least 3 arguments (0 given) What happens to the default arguments to time.__init__? What happens to the 2001, 10, 31 arguments to datetime.__init__? I would expect the output to be 2001-10-31 01:02:03.04 2001-10-31 00:00:00.00 Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Overloading ctor doesn't work?
Paul McGuire wrote: "Kent Johnson" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] Martin Häcker wrote: Hi there, I just tried to run this code and failed miserably - though I dunno why. Could any of you please enlighten me why this doesn't work? Here is a simpler test case. I'm mystified too: from datetime import datetime class time (datetime): def __init__(self, hours=0, minutes=0, seconds=0, microseconds=0): datetime.__init__(self, 2001, 10, 31, hours, minutes, seconds, microseconds) print time(1,2,3,4) # => 0001-02-03 04:00:00 print time()# => TypeError: function takes at least 3 arguments (0 given) What happens to the default arguments to time.__init__? What happens to the 2001, 10, 31 arguments to datetime.__init__? I would expect the output to be 2001-10-31 01:02:03.000004 2001-10-31 00:00:00.00 Kent I can't explain this behavior, but this version does work (uses datetime.combine instead of ctor) -- Paul from datetime import datetime, date as dt_date, time as dt_time class time_d (datetime): def __new__(cls, *args): # default to no microseconds if len(args)==3: args = args + (0,) if len(args)==4: tmpdate = datetime.today() h, mi, s, ms = args return datetime.combine(tmpdate, dt_time(h,mi,s,ms)) elif len(args)==7: y,m,d,h,mi,s,ms = args return datetime.combine(dt_date(y,m,d), dt_time(h,mi,s,ms)) else: raise TypeError, "wrong number of args" print time_d(2001,10,31,1,2,3,4) print time_d(1,2,3,4) print time_d(1,2,3) Ah, right. The light turns on... datetime is immutable so overriding the constructor doesn't change the constructed object. You have to override __new__ instead. http://www.python.org/2.2.1/descrintro.html#__new__ This works: from datetime import datetime class time (datetime): def __new__(cls, hours=0, minutes=0, seconds=0, microseconds=0): return datetime.__new__(cls, 2001, 10, 31, hours, minutes, seconds, microseconds) print time(1,2,3,4) # => 2001-10-31 01:02:03.04 print time()# => 2001-10-31 00:00:00 Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Overloading ctor doesn't work?
Nick Craig-Wood wrote: Martin Häcker <[EMAIL PROTECTED]> wrote: Now I thought, just overide the ctor of datetime so that year, month and day are static and everything should work as far as I need it. That is, it could work - though I seem to be unable to overide the ctor. :( Its a bug! http://sourceforge.net/tracker/index.php?func=detail&aid=720908&group_id=5470&atid=105470 However its been fixed in a recent Python 2.3. My example was developed in Python 2.4. The problem was the immutability of datetime. Kent (I was bitten by the same thing which used to fail but now works after an upgrade of python 2.3!) -- http://mail.python.org/mailman/listinfo/python-list
Re: Help with saving and restoring program state
Jacob H wrote:
Hello list...
I'm developing an adventure game in Python (which of course is lots of
fun). One of the features is the ability to save games and restore the
saves later. I'm using the pickle module to implement this. Capturing
current program state and neatly replacing it later is proving to be
trickier than I first imagined, so I'm here to ask for a little
direction from wiser minds than mine!
When my program initializes, each game object is stored in two places
-- the defining module, and in a list in another module. The following
example is not from my actual code, but what happens is the same.
(code contained in "globalstate" module)
all_fruit = []
(code contained in "world" module)
class Apple(object): # the class hierarchy goes back to object, anyway
def __init__(self):
self.foo = 23
self.bar = "something"
globalstate.all_fruit.append(self)
apple = Apple()
I enjoy the convenience of being able to refer to the same apple
instance through world.apple or globalstate.all_fruit, the latter
coming into play when I write for loops and so on. When I update the
instance attributes in one place, the changes are reflected in the
other place. But now comes the save and restore game functions, which
again are simplified from my real code:
My understanding of pickle is that it will correctly handle shared references in the saved data. So
if you pack all your global dicts into one list and pickle that list, you will get what you want.
See code changes below:
(code contained in "saveload" module)
import pickle
import world
import globalstate
def savegame(path_to_name):
world_data = {}
for attr, value in world.__dict__.items():
# actual code is selective about which attributes
# from world it takes -- I'm just keeping this
# example simple
world_data[attr] = value
the_whole_shebang = [ world_data, globalstate.all_fruit, globalstate.all_items ]
fp = open(path_to_name, "w")
pickle.dump(the_whole_shebang, fp)
fp.close()
def loadgame(path_to_name):
fp = open(path_to_name, "r")
the_whole_shebang = pickle.load(fp)
world_data, globalstate.all_fruit, globalstate.all_items =
the_whole_shebang
for attr, value in world_data.items():
setattr(world, attr, value)
fp.close()
Kent
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Re: fast list lookup
Klaus Neuner wrote: Hello, what is the fastest way to determine whether list l (with len(l)>3) contains a certain element? If you can use a set or dict instead of a list this test will be much faster. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: re.search - just skip it
[EMAIL PROTECTED] wrote:
Input is this:
SET1_S_W CHAR(1) NOT NULL,
SET2_S_W CHAR(1) NOT NULL,
SET3_S_W CHAR(1) NOT NULL,
SET4_S_W CHAR(1) NOT NULL,
;
.py says:
import re, string, sys
s_ora = re.compile('.*S_W.*')
lines = open("y.sql").readlines()
for i in range(len(lines)):
try:
if s_ora.search(lines[i]): del lines[i]
When you delete for example lines[0], the indices of the following lines change. So the former
lines[1] is now lines[0] and will not be checked.
The simplest way to do this is with a list comprehension:
lines = [ line for line in lines if not s_ora.search(line) ]
Even better, there is no need to make the intermediate list of all lines, you
can say
lines = [ line for line in open("y.sql") if not s_ora.search(line) ]
In Python 2.4 you don't have to make a list at all, you can just say
open("z.sql","w").writelines(line for line in open("y.sql") if not
s_ora.search(line))
;)
Kent
except IndexError:
open("z.sql","w").writelines(lines)
but output is:
SET2_S_W CHAR(1) NOT NULL,
SET4_S_W CHAR(1) NOT NULL,
;
It should delete every, not every other!
thx,
RasDJ
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Re: Help With Python
Thomas Guettler wrote:
# No comma at the end:
mylist=[]
for i in range(511):
mylist.append("Spam")
or just
mylist = ["Spam"] * 511
Kent
print ", ".join(mylist)
Thomas
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Re: Startying with Python, need some pointers with manipulating strings
Benji99 wrote:
I've managed to load the html source I want into an object
called htmlsource using:
import urllib
sock = urllib.urlopen("URL Link")
htmlSource = sock.read()
sock.close()
I'm assuming that htmlSource is a string with \n at the end of
each line.
NOTE: I've become very accustomed with the TStringList class in
Delphi so forgive me if I'm trying to work in that way with
Python...
Basically, I want to search through the whole string(
htmlSource), for a specific keyword, when it's found, I want to
know which line it's on so that I can retrieve that line and
then I should be able to parse/extract what I need using Regular
Expressions (which I'm getting quite confortable with). So how
can this be accomplished?
The Pythonic way to do this is to iterate through the lines of htmlSource and process them one at a
time.
htmlSource = htmlSource.split('\n') # Split on newline, making a list of lines
for line in htmlSource:
# Do something with line - check to see if it has the text of interest
You might want to look at Beautiful Soup. If you can find the links of interest by the tags around
them it might do what you want:
http://www.crummy.com/software/BeautifulSoup/
Kent
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Re: bound vs unbound functions
Michael Tobis wrote:
I'm trying to do metaprogramming. I'm sure I've got this all wrong
wrong wrong, but somehow my approach hasn't yet hit a brick wall.
Anyway, I'd like to dynamically add a method to an instance at
instantiation time. Something like
##
In [71]: class quux(object):
: def __init__(self,stuff):
: template = "def foo(self,b): print b + %s" % stuff
: exec(template)
: self.bazz = foo
:
In [72]: q = quux(5)
In [73]: q.bazz(4)
---
TypeError Traceback (most recent call
last)
/Users/tobis/PyNSol/
TypeError: foo() takes exactly 2 arguments (1 given)
In [74]: q.bazz("not much",4)
9
The thread Steve quoted suggests using new.instancemethod():
import new
class quux(object):
def __init__(self,stuff):
template = "def foo(self,b): print b + %s" % stuff
exec(template)
self.bazz = new.instancemethod(foo, self, quux)
There is no need for exec; you can define foo() directly as a nested
function:
class quux(object):
def __init__(self,stuff):
def foo(self,b):
print b + stuff
self.bazz = new.instancemethod(foo, self, quux)
Of course for this simple example you can just remember stuff as an
attribute:
class quux(object):
def __init__(self,stuff):
self.stuff = stuff
def bazz(self, b):
print b + self.stuff
Kent
So the straightforward question is why, even though bazz is a method of
class quux, it doesn't have that extra call parameter 'self'. Is this a
problem? If I actually need a reference to self is it OK to do:
In [76]: q.bazz(q,4)
?
The more vague question is why do people despise 'exec', and how should
I do this sort of thing instead?
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Re: Possible additions to the standard library? (WAS: About standardlibrary improvement)
Daniel Bickett wrote: |def reverse( self ): |""" |Return a reversed copy of string. |""" |string = [ x for x in self.__str__() ] |string.reverse() |return ''.join( string ) def reverse(self): return self[::-1] Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: changing local namespace of a function
Bo Peng wrote:
Dear list,
I have many dictionaries with the same set of keys and I would like to
write a function to calculate something based on these values. For
example, I have
a = {'x':1, 'y':2}
b = {'x':3, 'y':3}
def fun(dict):
dict['z'] = dict['x'] + dict['y']
fun(a) and fun(b) will set z in each dictionary as the sum of x and y.
My function and dictionaries are a lot more complicated than these so I
would like to set dict as the default namespace of fun. Is this
possible? The ideal code would be:
def fun(dict):
# set dict as local namespace
# locals() = dict?
z = x + y
You can part way there using keyword arguments. You just have to use dictionary syntax for changing
values in the dictionary:
>>> def f(d, x=None, y=None):
... d['z'] = x + y
...
>>> a = {'x':1, 'y':2}
>>> b = {'x':3, 'y':3}
>>>
>>> f(a, **a)
>>> a
{'y': 2, 'x': 1, 'z': 3}
>>> f(b, **b)
>>> b
{'y': 3, 'x': 3, 'z': 6}
Kent
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Re: changing local namespace of a function
Bo Peng wrote:
Yes. I thought of using exec or eval. If there are a dozen statements,
def fun(d):
exec 'z = x + y' in globals(), d
seems to be more readable than
def fun(d):
d['z'] = d['x'] + d['y']
But how severe will the performance penalty be?
You can precompile the string using compile(), you only have to do this
once.
>>> def makeFunction(funcStr, name):
... code = compile(funcStr, name, 'exec')
... def f(d):
... exec code in d
... del d['__builtins__'] # clean up extra entry in d
... return f
...
>>> f = makeFunction('z = x + y', 'f')
>>> a = {'x':1, 'y':2}
>>> b = {'x':3, 'y':3}
>>> f(a)
>>> a
{'y': 2, 'x': 1, 'z': 3}
>>> f(b)
>>> b
{'y': 3, 'x': 3, 'z': 6}
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Re: changing local namespace of a function
Bo Peng wrote:
Exec is slow since compiling the string and calls to globals() use a
lot of time. The last one is most elegant but __getattr__ and
__setattr__ are costly. The 'evil hack' solution is good since
accessing x and y takes no additional time.
Previous comparison was not completely fair since I could pre-compile
fun2 and I used indirect __setattr__. Here is the new one:
>>> # solution two: use exec
... def makeFunction(funcStr, name):
... code = compile(funcStr, name, 'exec')
... def f(d):
... exec code in d
... return f
...
>>> def fun2(d):
... myfun = makeFunction('z = x + y', 'myfun')
... for i in xrange(0,N):
... myfun(d)
... del d['__builtins__']
You are still including the compile overhead in fun2. If you want to see how fast the compiled code
is you should take the definition of myfun out of fun2:
myfun = makeFunction('z = x + y', 'myfun')
def fun2(d):
for i in xrange(0,N):
myfun(d)
del d['__builtins__']
Kent
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Re: changing local namespace of a function
Bo Peng wrote: Kent Johnson wrote: You are still including the compile overhead in fun2. If you want to see how fast the compiled code is you should take the definition of myfun out of fun2: I assumed that most of the time will be spent on N times execution of myfunc. Doh! Right. Kent -- http://mail.python.org/mailman/listinfo/python-list
Subclassing cElementTree.Element
Is it possible to subclass cElementTree.Element? I tried >>> import cElementTree as et >>> class Elt(et.Element): ... pass ... Traceback (most recent call last): File "", line 1, in ? TypeError: Error when calling the metaclass bases cannot create 'builtin_function_or_method' instances I want to create a tree where I can navigate from a node to its parent. The standard Element class doesn't seem to support this so I am trying to make a subclass that does. The XML files in question are large so the speed of cElementTree is very helpful. Thanks, Kent (apologies if this is a duplicate post) -- http://mail.python.org/mailman/listinfo/python-list
Re: Big development in the GUI realm
Fredrik Lundh wrote: Robert Kern wrote: Fair enough. The only time I've seen it in dead-tree print was in Heinlein's _Time Enough For Love_, unattributed to anyone else. Amazon.com "search inside the book" finds no hits for "malice" in this book. http://www.amazon.com/gp/reader/0441810764/102-7636110-6481700?v=search-inside&keywords=malice if that's true, it would seem that it predates the Hanlon reference by a couple of years: http://www.statusq.org/archives/2001/12/04 on the other hand, Google tells me that "Time Enough For Love" con- tains a couple of other famous stupidity quotes, including: "Never underestimate the power of human stupidity" "Search inside the book" finds this *twice* in "Time Enough For Love". Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Name of type of object
Jive Dadson wrote: I don't think I've quite got it. The application I'm writing has some similarities to an interactive shell. Like an interactive shell, it executes arbitrary code that it receives from an input stream. When it gets an exception, it should create an informative message, regardless of the type of exception. The traceback routine does that, somehow, some way, but I've tried to read that code and figure out how and I don't get it. The best I have so far is, class Exec_thread(BG_thread): """ Execute a line of code in the global namespace. """ def _process(s): """ Process one instruction """ try: exec s.product in globals() except (Exception), e: handle_error( typename(e)+ ": " + str(e) ) Have you looked at the traceback module? If you want to print the same kind of trace you get from Python, just use traceback.print_exc(). import traceback try: # whatever except: traceback.print_exc() Kent But that works only if the exception happens to be derived from Exception. How do I handle the general case? -- http://mail.python.org/mailman/listinfo/python-list
Re: Is this a bug? BOM decoded with UTF8
Diez B. Roggisch wrote: I know its easy (string.replace()) but why does UTF-16 do it on its own then? Is that according to Unicode standard or just Python convention? BOM is microsoft-proprietary crap. Uh, no. BOM is part of the Unicode standard. The intent is to allow consumers of Unicode text files to disambiguate UTF-8, big-endian UTF-16 and little-endian UTF-16. See http://www.unicode.org/faq/utf_bom.html#BOM Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: changing __call__ on demand
Stefan Behnel wrote: Hi! This somewhat puzzles me: Python 2.4 (#1, Feb 3 2005, 16:47:05) [GCC 3.3.4 (pre 3.3.5 20040809)] on linux2 Type "help", "copyright", "credits" or "license" for more information. .>>> class test(object): ... def __init__(self): ... self.__call__ = self.__call1 ... def __call1(self): ... print 1 ... def __call__(self): ... print 2 ... .>>> t = test() .>>> t() 2 It works the way you want if test is an old-style class: >>> class test: ... def __init__(self): ...self.__call__ = self.__call1 ... def __call1(self): ...print 1 ... def __call__(self): ...print 2 ... >>> t=test() >>> t() 1 Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Second posting - Howto connect to MsSQL
John Fabiani wrote: Hi, Since this is (sort of) my second request it must not be an easy solution. Are there others using Python to connect MsSQL? At the moment I'd accept even a windows solution - although, I'm looking for a Linux solution. On Windows, you can use http://sourceforge.net/projects/adodbapi Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Can't subclass datetime.datetime?
Grant Edwards wrote: Is it true that a datetime object can convert itself into a string, but not the other way around? IOW, there's no simple way to take the output from str(d) and turn it back into d? According to this thread, a patch has been checked in that adds strptime() to datetime. So there is something to look forward to... http://tinyurl.com/4fbkb Kent -- http://mail.python.org/mailman/listinfo/python-list
Write Unicode str as utf-8
Python support unicode, but some library don't. Write is one of them. When writing a csv file, The rows contains numbers and unicode str. It is a little pain to first convert all unicode str to utf-8 before writing the row. Are there anyway I can patch python such that It will convert the unicode string to utf-8 before the write? Where should I start? Best rgs, Kent Sin -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie help
Chad Everett wrote: Nope, I am trying to learn it on my own. I am using the book by Michael Dawson. You might be interested in the Python tutor mailing list which is specifically intended for beginners. http://mail.python.org/mailman/listinfo/tutor Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie help
Kent Johnson wrote: You might be interested in the Python tutor mailing list which is specifically intended for beginners. http://mail.python.org/mailman/listinfo/tutor Ah, I don't mean to imply that this list is unfriendly to beginners, or that you are not welcome here! Just pointing out another resource. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: more os.walk() issues... probably user error
rbt wrote: rbt wrote: This function is intended to remove unwanted files and dirs from os.walk(). It will return correctly *IF* I leave the 'for fs in fs_objects' statement out (basically leave out the entire purpose of the function). It's odd, when the program goes into that statment... even when only a 'pass', and nothing else is present, nothing is returned. Why is that? I'm testing Python 2.4 on Linux x86 and WinXP. Results are the same on either platform. def build_clean_list(self, path): file_skip_list = ['search_results.txt'] dir_skip_list = ['dev', 'proc', 'Temporary Internet Files'] fs_objects = os.walk(path, topdown=True) fs_objects is a generator, not a list. This loop is exhausting fs_objects, so when you return fs_objects is at the end of iteration, there is nothing left. ## for fs in fs_objects: ## ##for f in fs[2]: ##if f in file_skip_list: ##print f ##fs[2].remove(f) ## ##for d in fs[1]: ##if d in dir_skip_list: ##print d ##fs[1].remove(d) Add this here: yield fs and take out the return. This turns build_clean_list() into a generator function and you will be able to iterate the result. Kent return fs_objects Just to clarify, it's wrong of me to say that 'nothing is returned'... in either case, this is what is returned: Here's what was returned and its type: But, I can't iterate over the returned object when I descend into the for statement I mentioned above. -- http://mail.python.org/mailman/listinfo/python-list
Re: more os.walk() issues... probably user error
rbt wrote: ## for fs in fs_objects: ## ##for f in fs[2]: ##if f in file_skip_list: ##print f ##fs[2].remove(f) ## ##for d in fs[1]: ##if d in dir_skip_list: ##print d ##fs[1].remove(d) Will the changes I made (file and dir removals from os.walk()) be reflected in the generator object? Is it safe to remove objects this way and pass the results in a generator on to another function? Sorry for all the questions, I just like to fully understand something before I start doing it with confidence. Yes. The docs for os.walk() explicitly state, "When topdown is true, the caller can modify the dirnames list in-place (perhaps using del or slice assignment), and walk() will only recurse into the subdirectories whose names remain in dirnames." So changes to the dir list affect the iteration; changes to the file list directly affect the value you return to the caller. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Alternative to standard C "for"
James Stroud wrote: It seems I need constructs like this all of the time i = 0 while i < len(somelist): if oughta_pop_it(somelist[i]): somelist.pop(i) else: i += 1 There has to be a better way... somelist[:] = [ item for item in somelist if not oughta_pop_it(item) ] Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: lambda closure question
Ted Lilley wrote: What I want to do is pre-load functions with arguments by iterating through a list like so: class myclass: ...pass def func(self, arg): ...print arg mylist = ["my", "sample", "list"] for item in mylist: ...setattr(myclass, item, lamdba self: func(self, item)) This attaches a list of functions to the class, making them bound methods when called from a class instance. obj = myclass() obj.list() list Unfortunately, it doesn't work. It seems the closure keeps track of the variable fed to it dynamically - if the variable changes after the lambda is created, the lambda still references the _variable_ not the original _value_ and so gets the new value like so: obj.sample() list obj.my() list The closure isn't bound until the scope containing it is exited. A simple workaround is to bind item as a default argument to the lambda: for item in mylist: setattr(myclass, item, lambda self, item=item: func(self, item)) You can also make a helper function that returns the closure, the closure will be bound each time the helper returns: def make_f(item): def f(self): func(self, item) return f mylist = ["my", "sample", "list"] for item in mylist: setattr(myclass, item, make_f(item)) Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: could that be a mutable object issue ?
Philippe C. Martin wrote: If I do this: print 'LEN OF BOOK BEFORE APPEND: ', len(pickle.dumps(self.__m_rw)) self.__m_rw.books.append( [p_col1,p_col2,p_col3] ) print 'LEN OF BOOK AFTER APPEND: ', len(pickle.dumps(self.__m_rw)) I get the same length before and after append. when I print self.__m_rw.books, I see my 'appends' in there, yet the pickled object does not change. How is __m_rw.books defined? If it is a class attribute of the class of __m_rw you will see this behavior. e.g. >>> class Mrw: ... books = [] ... >>> m=Mrw() >>> class Mrw: ... books = [] ... >>> __m_rw = Mrw() >>> __m_rw.books.append(1) >>> __m_rw.books [1] but __m_rw.books will not be pickled with __m_rw because it belongs to the class, not the instance. The fix is to declare books as an instance attribute: class Mrw: def __init__(self): self.books = [] Kent Any clue ? Thanks Philippe -- http://mail.python.org/mailman/listinfo/python-list
Re: How Do I get Know What Attributes/Functions In A Class?
Hans Nowak wrote: [EMAIL PROTECTED] wrote: Hi, I'm new to python. Given a class, how can I get know what attributes/functins in it without dig into the source? Use the dir function: >>> from smtplib import SMTP >>> dir(SMTP) ['__doc__', '__init__', '__module__', 'close', 'connect', 'data', 'debuglevel', 'docmd', 'does_esmtp', 'ehlo', 'ehlo_resp', 'expn', 'file', 'getreply', 'has_extn', 'helo', 'helo_resp', 'help', 'login', 'mail', 'noop', 'putcmd', 'quit', 'rcpt', 'rset', 'send', 'sendmail', 'set_debuglevel', 'starttls', 'verify', 'vrfy'] To get more detailed information than just a list of names, see the inspect module. Or use 'help' (which is build on top of inspect): >>> from smtplib import SMTP >>> help(SMTP) Help on class SMTP in module smtplib: class SMTP | This class manages a connection to an SMTP or ESMTP server. | SMTP Objects: | SMTP objects have the following attributes: | helo_resp | This is the message given by the server in response to the | most recent HELO command. etc. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: recommended way of generating HTML from Python
Michele Simionato wrote:
The problem is a problem of standardization, indeed. There plenty of
recipes to
do the same job, I just would like to use a blessed one (I am teaching
a Python
course and I do not know what to recommend to my students).
Why not teach your students to use a template system?
FWIW, here is a my version of the recipe (stripped down to the bare
essentials)
.def makeattr(dict_or_list_of_pairs):
.dic = dict(dict_or_list_of_pairs)
.return " ".join("%s=%r" % (k, dic[k]) for k in dic)
.class HTMLTag(object):
.def __getattr__(self, name):
.def tag(value, **attr):
."""value can be a string or a sequence of strings."""
.if hasattr(value, "__iter__"): # is iterable
.value = " ".join(value)
.return "<%s %s>%s\n" % (name, makeattr(attr), value,
name)
.return tag
# example:
.html = HTMLTag()
.tableheader = ["field1", "field2"]
.tablebody = [["a1", "a2"],
. ["b1", "b2"]]
.html_header = [html.tr(html.th(el) for el in tableheader)]
.html_table = [html.tr(html.td(el) for el in row) for row in tablebody]
.print html.table(html_header + html_table)
*Shudder*
I've written web pages this way (using a pretty nice Java HTML generation package) and I don't
recommend it. In my experience, this approach has several drawbacks:
- as soon as the web page gets at all complex, the conceptual shift from HTML to code and back is
difficult.
- It is hard to work with a designer. The designer will give you sample web pages which then have to
be hand-translated to code. Changes to the web page have to be located in the code.
- There is no separation of content and presentation
IMO templating systems are a much better solution. They let you express HTML in HTML directly; you
communicate with a designer in a language the designer understands; you can separate content and
presentation.
Kent
Michele Simionato
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Re: On eval and its substitution of globals
Paddy wrote: Hi, I got tripped up on the way eval works with respect to modules and so wrote a test. It seems that a function carries around knowledge of the globals() present when it was defined. (The .func_globals attribute)? When evaluated using eval(...) the embedded globals can be overridden with the one passed through the eval(...) call If however you create a new function that calls the first then eval's global argument is only substituted in the outer call! TEST: = def f1(): return A < B ... def z(): return f1() ... eval(f1.func_code,dict(A=1,B=2)) True eval(z.func_code,dict(A=1,B=2, f1=f1)) Traceback (most recent call last): File "", line 1, in ? File "", line 1, in z File "", line 1, in f1 NameError: global name 'A' is not defined ENDTEST === Is there a way to do a deep substitution of the globals? A workaround is to implement z() using eval() again, this forces f1() to use the same globals passed to z(): >>> def z(): return eval(f1.func_code) ... >>> eval(z.func_code,dict(A=1,B=2, f1=f1)) True Kent I should add that f1 is given as-is. I can modify z, and f1 is just one of many functions given and function z is some boolean function of the f's Thanks, Pad. -- http://mail.python.org/mailman/listinfo/python-list
Re: Style guide for subclassing built-in types?
[EMAIL PROTECTED] wrote: p.s. the reason I'm not sticking to reversed or even reverse : suppose the size of the list is huge. reversed() returns an iterator so list size shouldn't be an issue. What problem are you actually trying to solve? Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: unicode(obj, errors='foo') raises TypeError - bug?
Steven Bethard wrote: Mike Brown wrote: class C: ... def __str__(self): ... return 'asdf\xff' ... o = C() unicode(o, errors='replace') Traceback (most recent call last): File "", line 1, in ? TypeError: coercing to Unicode: need string or buffer, instance found [snip] What am I doing wrong? Is this a bug in Python? No, this is documented behavior[1]: """ unicode([object[, encoding [, errors]]]) ... For objects which provide a __unicode__() method, it will call this method without arguments to create a Unicode string. For all other objects, the 8-bit string version or representation is requested and then converted to a Unicode string using the codec for the default encoding in 'strict' mode. """ Note that the documentation basically says that it will call str() on your object, and then convert it in 'strict' mode. You should either define __unicode__ or call str() manually on the object. Not a bug, I guess, since it is documented, but it seems a bit bizarre that the encoding and errors parameters are ignored when object does not have a __unicode__ method. Kent STeVe [1] http://docs.python.org/lib/built-in-funcs.html -- http://mail.python.org/mailman/listinfo/python-list
Re: unicode(obj, errors='foo') raises TypeError - bug?
Martin v. LÃwis wrote: Steven Bethard wrote: Yeah, I agree it's weird. I suspect if someone supplied a patch for this behavior it would be accepted -- I don't think this should break backwards compatibility (much). Notice that the "right" thing to do would be to pass encoding and errors to __unicode__. If the string object needs to be told what encoding it is in, why not any other other object as well? Unfortunately, this apparently was overlooked, and now it is too late to change it (or else the existing __unicode__ methods would all break if they suddenly get an encoding argument). Could this be handled with a try / except in unicode()? Something like this: >>> class A: ... def u(self): # __unicode__ with no args ... print 'A.u()' ... >>> class B: ... def u(self, enc, err): # __unicode__ with two args ... print 'B.u()', enc, err ... >>> def convert(obj, enc='ascii', err='strict'): # unicode() function delegates to u() ... try: ... obj.u(enc, err) ... except TypeError: ... obj.u() ... >>> convert(a) A.u() >>> convert(a, 'utf-8', 'replace') A.u() >>> convert(b) B.u() ascii strict >>> convert(b, 'utf-8', 'replace') B.u() utf-8 replace As for using encoding and errors on the result of str() conversion of the object: how can the caller know what encoding the result of str() is in, reasonably? The same way that the caller will know the encoding of a byte string, or of the result of str(some_object) - in my experience, usually by careful detective work on the source of the string or object followed by attempts to better understand and control the encoding used throughout the application. It seems more correct to assume that the str() result in in the system default encoding. To assume that in absence of any guidance, sure, that is consistent. But to ignore the guidance the programmer attempts to provide? One thing that hasn't been pointed out in this thread yet is that the OP could just define __unicode__() on his class to do what he wants... Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Communication between JAVA and python
Jacques Daussy wrote: Hello How can I transfert information between a JAVA application and a python script application. I can't use jython because, I must use python interpreter.I think to socket or semaphore, but can I use it on Windows plateform ? Jython has an interpreter and Windows has sockets. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: On eval and its substitution of globals
Paddy wrote: I do in fact have the case you mention. I am writing a module that will manipulate functions of global variables where the functions are defined in another module. Would it be possible to have your functions take arguments instead of globals? That would seem to be a better design. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Like overloading __init__(), but how?
John M. Gabriele wrote: I know that Python doesn't do method overloading like C++ and Java do, but how am I supposed to do something like this: This was just discussed. See http://tinyurl.com/6zo3g Kent - incorrect #!/usr/bin/python class Point3d: pass class Vector3d: """A vector in three-dimensional cartesian space.""" def __init__( self ): """Create a Vector3d with some reasonable default value.""" x, y, z = 0.0, 0.0, 0.0 def __init__( self, x_from, y_from, z_from, x_to, y_to, z_to ): """Create a Vector3d from x-y-z coords.""" # ... pass def __init__( self, point_from, point_to ): """Create a Vector3d from two Point3d objects.""" # ... pass def __init__( self, same_as_this_vec ): """Create a Vector3d from a copy of another one.""" # ... pass p = Point3d() p2 = Point3d() # v = Vector3d( p2, p ) -- Nope. Only the last __init__() counts. -- /incorrect --- Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: Source Encoding GBK/GB2312
[EMAIL PROTECTED] wrote: When I specify an source encoding such as: # -*- coding: GBK -*- or # -*- coding: GB2312 -*- as the first line of source, I got the following error: SyntaxError: 'unknown encoding: GBK' Does this mean Python does not support GBK/GB2312? What do I do? GB2312 is supported in Python 2.4. GB2312 support can be added to Python 2.3 with the CJKCodecs package: http://cjkpython.i18n.org/ Kent - narke -- http://mail.python.org/mailman/listinfo/python-list
Re: split a directory string into a list
[EMAIL PROTECTED] wrote:
QUESTION:
How do I split a directory string into a list in Python, eg.
'/foo/bar/beer/sex/cigarettes/drugs/alcohol/'
becomes
['foo','bar','beer','sex','cigarettes','drugs','alcohol']
>>> '/foo/bar/beer/sex/cigarettes/drugs/alcohol/'.strip('/').split('/')
['foo', 'bar', 'beer', 'sex', 'cigarettes', 'drugs', 'alcohol']
Kent
I was looking at the os.path.split command, but it only seems to
separate the filename from the path (or am I just using it wrong?). I
don't want to do it manually if I can help it, as there will have to be
exceptions for the cases where there is (not) a trailing (leading)
slash, or escape sequences involving /. Is there a built in command for
this?
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Re: Converting HTML to ASCII
gf gf wrote: Hi. I'm looking for a Python lib to convert HTML to ASCII. You might find these threads on comp.lang.python interesting: http://tinyurl.com/5zmpn http://tinyurl.com/6mxmb Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: class factory example needed (long)
Gary Ruben wrote: OK, I've managed to get this to work with Rainer's method, but I realised it is not the best way to do it, since the methods are being added by the constructor, i.e. they are instance methods. This means that every time a foo object is created, a whole lot of code is being run. It would be better to do the same thing with class 'static' methods, if this is possible, so that the methods are created just once. Is this possible? Here is a solution using a metaclass: import Numeric class MetaFoo(type): def __init__(cls, name, bases, d): super(MetaFoo, cls).__init__(cls, name, bases, d) for u in ['sqrt', 'cos', 'tan']: setattr(cls, u, lambda self, uf=getattr(Numeric, u): uf(self.value + 42.0)) class Foo(object): __metaclass__ = MetaFoo def __init__(self, value): self.value = float(value) f = Foo(7) print f.sqrt() Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Regular Expressions: large amount of or's
André Søreng wrote:
Hi!
Given a string, I want to find all ocurrences of
certain predefined words in that string. Problem is, the list of
words that should be detected can be in the order of thousands.
With the re module, this can be solved something like this:
import re
r = re.compile("word1|word2|word3|...|wordN")
r.findall(some_string)
Unfortunately, when having more than about 10 000 words in
the regexp, I get a regular expression runtime error when
trying to execute the findall function (compile works fine, but slow).
I don't know if using the re module is the right solution here, any
suggestions on alternative solutions or data structures which could
be used to solve the problem?
If you can split some_string into individual words, you could look them up
in a set of known words:
known_words = set("word1 word2 word3 ... wordN".split())
found_words = [ word for word in some_string.split() if word in known_words ]
Kent
André
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Re: Regular Expressions: large amount of or's
André Søreng wrote:
Hi!
Given a string, I want to find all ocurrences of
certain predefined words in that string. Problem is, the list of
words that should be detected can be in the order of thousands.
With the re module, this can be solved something like this:
import re
r = re.compile("word1|word2|word3|...|wordN")
r.findall(some_string)
Unfortunately, when having more than about 10 000 words in
the regexp, I get a regular expression runtime error when
trying to execute the findall function (compile works fine, but slow).
What error do you get? What version of Python are you using? re was changed in Python 2.4 to avoid
recursion, so if you are getting a stack overflow in Python 2.3 you should try 2.4.
Kent
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Re: Help- Simple recursive function to build a list
actuary77 wrote: I am trying to write simple recursive function to build a list: def rec(n,alist=[]): _nl=alist[:] print n,_nl if n == 0: print n,_nl return _nl else: _nl=_nl+[n] rec(n-1,_nl) should be return rec(n-1,_nl) >>> def rec(n,alist=[]): ... _nl=alist[:] ... print n,_nl ... if n == 0: ... print n,_nl ... return _nl ... else: ... _nl=_nl+[n] ... return rec(n-1,_nl) ... >>> _nl = rec(4) 4 [] 3 [4] 2 [4, 3] 1 [4, 3, 2] 0 [4, 3, 2, 1] 0 [4, 3, 2, 1] >>> print _nl [4, 3, 2, 1] Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Help- Recursion v. Iter Speed comparison
Roy Smith wrote: I believe Edouard Manet said it best, "Damn your recursion, Henri. Iteration, however complex, is always more efficient." (extra points if you can identify the source of that quote). It's not clear what language Manet was talking about when he said that, but it's pretty much a universal truth. GIYF http://www.sprex.com/else/sidman/boite.html Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiline regex help
Yatima wrote:
Hey Folks,
I've got some info in a bunch of files that kind of looks like so:
Gibberish
53
MoreGarbage
12
RelevantInfo1
10/10/04
NothingImportant
ThisDoesNotMatter
44
RelevantInfo2
22
BlahBlah
343
RelevantInfo3
23
Hubris
Crap
34
and so on...
Anyhow, these "fields" repeat several times in a given file (number of
repetitions varies from file to file). The number on the line following the
"RelevantInfo" lines is really what I'm after. Ideally, I would like to have
something like so:
RelevantInfo1 = 10/10/04 # The variable name isn't actually important
RelevantInfo3 = 23 # it's just there to illustrate what info I'm
# trying to snag.
Here is a way to create a list of [RelevantInfo, value] pairs:
import cStringIO
raw_data = '''Gibberish
53
MoreGarbage
12
RelevantInfo1
10/10/04
NothingImportant
ThisDoesNotMatter
44
RelevantInfo2
22
BlahBlah
343
RelevantInfo3
23
Hubris
Crap
34'''
raw_data = cStringIO.StringIO(raw_data)
data = []
for line in raw_data:
if line.startswith('RelevantInfo'):
key = line.strip()
value = raw_data.next().strip()
data.append([key, value])
print data
Score[RelevantInfo1][RelevantInfo3] = 22 # The value from RelevantInfo2
I'm not sure what you mean by this. Do you want to build a Score dictionary
as well?
Kent
Collected from all of the files.
So, there would be several of these "scores" per file and there are a bunch
of files. Ultimately, I am interested in printing them out as a csv file but
that should be relatively easy once they are trapped in my array of doom
.
I've got a fairly ugly "solution" (I am using this term *very* loosely)
using awk and his faithfail companion sed, but I would prefer something in
python.
Thanks for your time.
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Re: passing lists
Earl Eiland wrote: This message contains the responses to two previous messages: In response to Steven B.,the statements Raw_packet_queue = enqueue(..., Raw_packet_queue, ...) print 'Sort 1 Raw_packet_queue is', Raw_packet_queue produce the output Sort 1 Raw_packet_queue is [[(, '\x00\x00\xd1\xf0\x [EMAIL PROTECTED] 81\x8a\x02\xbf\xb1\x13\x00\x16\xe5/\xd5\xa7vu\x0e\x08\x80\x10\xf8\xe0\x8a[\x00\x 00\x01\x01\x08\n\x15\xb7\x13\xba\x8e\x91\x9a\xfd'), ['E\x00\x004', '@\x00', '\x0 6', '\x89N\xa2j\x81\x8a\x02\xbf\xb1\x13\x00\x16\xe5/\xd5\xa7vu\x0e\x08\x80\x10\x f8\xe0\x8a[\x00\x00\x01\x01\x08\n\x15\xb7\x13\xba\x8e\x91\x9a\xfd']]] This consists of two lists [[pcap packet header, pcap packet body], [a list of selected IP header fields]]. Raw_packet_queue[0][0][1] should return the 'pcap packet body' list element. No, Raw_packet_queue[0] is [pcap packet header, pcap packet body] so Raw_packet_queue[0][1] is pcap packet body. Raw_packet_queue[0][0][1] is (pcap packet header)[1] which doesn't work. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: binutils "strings" like functionality?
cjl wrote: Hey all: I am working on a little script that needs to pull the strings out of a binary file, and then manipulate them with python. The command line utility "strings" (part of binutils) has exactly the functionality I need, but I was thinking about trying to implement this in pure python. I did some reading on opening and reading binary files, etc., and was just wondering if people think this is possible, or worth my time (as a learning exercise), or if something like this already exists. I think a bare-bones version is pretty simple: - read the file - use re.split() to split on non-printable characters (string.printable could be handy here) - print anything in the resulting list that is at least 4 characters Since you mention this as a learning exercise I'll refrain from posting code but it's only a handful of lines...of course implementing all of 'strings' is a bit more work. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: greedy match wanted
alexk wrote: My problem is as follows. I want to match urls, and therefore I have a group of long valid domain names in my regex: (?:com|org|net|biz|info|ac|cc|gs|ms| sh|st|tc|tf|tj|to|vg|ad|ae|af|ag| com\.ag|ai|off\.ai|al|an|ao|aq| com\.ar|net\.ar|org\.ar|as|at|co\.at| ... ) ... However, for a url like kuku.com.to it matches the kuku.com part, while I want it to match the whole kuku.com.to. Notice that both "com" and "com.to" are present in the group above. 1. How do I give precedence for "com.to" over "com" in the above group ? Maybe I can somehow sort it by lexicographic order and then by length, or divide it to a set of sub-groups by length ? According to the docs for re: "As the target string is scanned, REs separated by "|" are tried from left to right. When one pattern completely matches, that branch is accepted. This means that once A matches, B will not be tested further, even if it would produce a longer overall match. In other words, the "|" operator is never greedy." So putting "com.to" before "com" does what you want. >>> import re >>> re.search(r'com|com\.to', 'kuku.com.to').group() 'com' >>> re.search(r'com\.to|com', 'kuku.com.to').group() 'com.to' Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with recursion
vegetax wrote: I am trying to make convert a directory "tree" in a list of list, but cant find the algoritm =( ,for example a directory tree like : #!/usr/bin/python from os import listdir from os.path import isdir,join,basename dirpath = '/tmp/test/' res = [] def rec(f): print f for ele in listdir(f): ele = join(f,ele) if isdir(ele): # append the directory name res.append(basename(ele)) rec(ele) else : res.append(basename(ele)) rec(dirpath) print res The problem is that you are always appending individual names to the same list. If you make rec() return a list and append that to the current list you get what you want: #!/usr/bin/python from os import listdir from os.path import isdir,join,basename dirpath = '/tmp/test/' def rec(f): res = [] for ele in listdir(f): res.append(ele) ele = join(f,ele) if isdir(ele): res.append(rec(ele)) return res print rec(dirpath) Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiline regex help
Here is another attempt. I'm still not sure I understand what form you want the data in. I made a
dict -> dict -> list structure so if you lookup e.g. scores['10/11/04']['60'] you get a list of all
the RelevantInfo2 values for Relevant1='10/11/04' and Relevant2='60'.
The parser is a simple-minded state machine that will misbehave if the input does not have entries
in the order Relevant1, Relevant2, Relevant3 (with as many intervening lines as you like).
All three values are available when Relevant3 is detected so you could do something else with them
if you want.
HTH
Kent
import cStringIO
raw_data = '''Gibberish
53
MoreGarbage
12
RelevantInfo1
10/10/04
NothingImportant
ThisDoesNotMatter
44
RelevantInfo2
22
BlahBlah
343
RelevantInfo3
23
Hubris
Crap
34
Gibberish
53
MoreGarbage
12
RelevantInfo1
10/10/04
NothingImportant
ThisDoesNotMatter
44
RelevantInfo2
22
BlahBlah
343
RelevantInfo3
23
Hubris
Crap
34
SecondSetofGarbage
2423
YouGetThePicture
342342
RelevantInfo1
10/10/04
HoHum
343
MoreStuffNotNeeded
232
RelevantInfo2
33
RelevantInfo3
44
sdfsdf
RelevantInfo1
10/11/04
InsertBoringFillerHere
43234
Stuff
MoreStuff
RelevantInfo2
45
ExcitingIsntIt
324234
RelevantInfo3
60
Lalala'''
raw_data = cStringIO.StringIO(raw_data)
scores = {}
info1 = info2 = info3 = None
for line in raw_data:
if line.startswith('RelevantInfo1'):
info1 = raw_data.next().strip()
elif line.startswith('RelevantInfo2'):
info2 = raw_data.next().strip()
elif line.startswith('RelevantInfo3'):
info3 = raw_data.next().strip()
scores.setdefault(info1, {}).setdefault(info3, []).append(info2)
info1 = info2 = info3 = None
print scores
print scores['10/11/04']['60']
print scores['10/10/04']['23']
## prints:
{'10/10/04': {'44': ['33'], '23': ['22', '22']}, '10/11/04': {'60': ['45']}}
['45']
['22', '22']
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Re: Multiline regex help
Steven Bethard wrote:
Kent Johnson wrote:
for line in raw_data:
if line.startswith('RelevantInfo1'):
info1 = raw_data.next().strip()
elif line.startswith('RelevantInfo2'):
info2 = raw_data.next().strip()
elif line.startswith('RelevantInfo3'):
info3 = raw_data.next().strip()
scores.setdefault(info1, {}).setdefault(info3, []).append(info2)
info1 = info2 = info3 = None
Very pretty. =) I have to say, I hadn't ever used iterators this way
before, that is, calling their next method from within a for-loop. I
like it. =)
I confess I have a nagging suspicion that someone who actually knows something about CPython
internals will tell me why it's a bad idea...but it sure is handy!
Thanks for opening my mind. ;)
My pleasure :-)
Kent
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Re: There's GOT to be a better way!
[EMAIL PROTECTED] wrote: This would be a good case to use OO design, imo. The following works fine. Simply instantiate the object, call the method, and you can access (and manipulate) the "module's" variable to your heart's content. module.py class object: Ouch. Use a different name than 'object', which is the base class of all new-style classes. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: jython question (interesting behavior)
pythonUser_07 wrote:
Is this the correct place to post a jython question?
I posted the following in the jython group, but I figured I'd post here
too:
_
I am assuming that the PythonInterpreter environment is not a unique
environment from within a jvm.
Here is some pseudo code to show what I am talking about
1) create a jython module file, lets call it "mytest"
with a simple static class
class simpleS:
myVar = "test01"
2) Now set up two interpreter environments from within
the same jvm
PythonInterpreter py = new PythonInterpreter()
PythonInterpreter py1 = new PythonInterpreter()
3) now in both interpreters, import the module
py.exec("import mytest")
py1.exec("import mytest")
Now for both interpreters run
"print mytest.simpleS.myVar"
4) Now for the crazy part.
in the py interpreter run
"mytest.simpleS.myVar = 'test02'
in py1 look at the value
"print mytest.simpleS.myVar"
Very interesting behavior. So it seems that each python interpreter
instance does not act as its own seperate space.
My understanding is that the two PythonInterpreters wrap a single PySystemState which is where the
modules are cached. So they share the same modules. If you want different behaviour you should give
them each their own PySystemState.
Kent
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Re: Setting default option values for Tkinter widgets
Steve Holden wrote: [EMAIL PROTECTED] wrote: Eric, your tagline doesn't parse correctly on my Python 2.4 shell. So, are you using Windows? If you interchange single and double quotes it works on Windows too python -c "print ''.join([chr(154 - ord(c)) for c in 'U(17zX(%,5.z^5(17l8(%,5.Z*(93-965$l7+-'])" Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Integer From A Float List?!?
[EMAIL PROTECTED] wrote: Hello NG, sorry to bother you again with this question... I never used the "timeit" function, and I would like to ask you if the call I am doing is correct: C:\Python23\Lib>python timeit.py -n 1000 -s "from Numeric import ones" -s "floa ts=ones((1000,1),'f')" -s "ints = floats.astype(int)" 1000 loops, best of 3: 0.0536 usec per loop The -s option indicates Setup steps that are done outside the timing loop. So you have timed 1000 empty loops, which is indeed impressively fast :-) The correct command is C:\Python23\Lib>python23 timeit.py -n 1000 -s "from Numeric import ones" -s "floats=ones((1000,1),'f')" "ints = floats.astype(int)" 1000 loops, best of 3: 30.7 usec per loop which is still impressively fast compared to map: C:\Python23\Lib>python timeit.py -s "floats = map(float, range(1000))" "ints= map(int, floats)" 1000 loops, best of 3: 572 usec per loop Kent I used Numeric module to create a 1000 floats matrix of ones, and it seems to me that is a lot faster than other solutions... but probably I am doing something wrong in my call to the timeit function... Thank you a lot. Andrea. -- http://mail.python.org/mailman/listinfo/python-list
Re: Relative imports
Michael Hoffman wrote: Chris wrote: Why do relative imports cause warnings in PyLint? http://www.python.org/peps/pep-0328.html#rationale-for-absolute-imports I notice that this section says that from __future__ import absolute_import will be a feature of Python 2.4. Apparently it didn't make the cut. I've posted a bug report. Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Accessing Python parse trees
Manlio Perillo wrote: Anyway, here is an example of what I would like to do: #begin def foo(**kwargs): print kwargs foo(a = 1, b = 2, c = 3) #end In the current implementation kwargs is a dict, but I need to have the keyword argument sorted. Unfortunately subclassing fron dict and installing the class in the __builtin__ module (with the name 'dict') does not work, CPython uses only builtin types. With the compiler module I can obtain the keyword arguments in the order the were specified. The problem is how to do this for every call to foo! Why not just pass the kind of argument you want? What is it you really need to do? def foo(kwds): print kwds foo(MyDict(a = 1, b = 2, c = 3)) Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Relative imports
Chris wrote: After reading that link I tried to change my imports like this: " from .myPythonFileInTheSameFolder import MyClass" This style of import is not yet implemented. I'm getting more and more confused... How can I correctly do a relative import ? I think your choices are - keep doing what you have been doing and ignore the warnings from PyLint - keep doing what you have been doing and turn off the warnings from PyLint - rewrite your imports to be absolute imports Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: Equality operator
italy wrote: Why doesn't this statement execute in Python: 1 == not 0 I get a syntax error, but I don't know why. Because == has higher precedence than 'not', so you are asking for (1 == not) 0 Try >>> 1 == (not 0) True Kent Thanks, Adam Roan -- http://mail.python.org/mailman/listinfo/python-list
Re: Can a method in one class change an object in another class?
Stewart Midwinter wrote: I've got an app that creates an object in its main class (it also creates a GUI). My problem is that I need to pass this object, a list, to a dialog that is implemented as a second class. I want to edit the contents of that list and then pass back the results to the first class. So my question is, can a method in one class change an object in another class? Diez and Lee have shown you two ways to do this. If the answer is no, I suppose I could pass in the list as an argument when I create the second class, then return the contents of the list when I end the methods in that second class. This is almost what your example does, but you have made a small error. See below. alternatively, I could make the list a global variable, then it would be available to all classes. I have a nagging feeling though that global variables are to be avoided on general principle. Is this correct? Yes, it is correct. Here's a simple example app that tries to have one class change the object in another class. It doesn't give the behaviour I want, though. --- #objtest.py class first: def __init__(self): a = 'a' self.a = a print self.a def update(self): print 'initially, a is', self.a self.a = second(self.a) The line above is creating an instance of second and assigning it to self.a. What you want to do is create an instance of second, *call* it, and assign the result to self.a. So you should have self.a = second(self.a)(self.a) The self.a parameter passed to second is never used. If you change second.__init__ to def __init__(self): pass then the call in update() will be self.a = second()(self.a) Kent print 'afterwards, a is', self.a class second: def __init__(self, a): pass def __call__(self, a): a = 'aa' return a if __name__ == '__main__': app = first() app.update() thanks, -- Stewart Midwinter [EMAIL PROTECTED] [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: function with a state
Patrick Useldinger wrote: The short answer is to use the global statement: globe=0 def myFun(): global globe globe=globe+1 return globe more elegant is: globe=0 globe=myfun(globe) def myFun(var): return var+1 This mystifies me. What is myfun()? What is var intended to be? Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: function with a state
Patrick Useldinger wrote: Kent Johnson wrote: globe=0 globe=myfun(globe) def myFun(var): return var+1 This mystifies me. What is myfun()? What is var intended to be? myfun is an error ;-) should be myFun, of course. var is parameter of function myFun. If you call myFun with variable globe, all references to var will be replaced by globe inside function myFun. Oh. I thought there was some deep magic here that I was missing :-) You also have to define myFun before you call it... def myFun(var): return var+1 globe = 0 ... globe = myFun(globe) Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: reversed heapification?
Stefan Behnel wrote: Hi! I need a general-purpose best-k sorting algorithm and I'd like to use heapq for that (heapify + heappop*k). The problem is that heapify and heappop do not support the "reverse" keyword as known from sorted() and list.sort(). While the decorate-sort-undecorate pattern allows me to replace the "key" option, I do not see an obvious way to have heapq work in a reverse way without making assumptions on the data. heapq.nlargest() heapq.nsmallest() ? Python 2.4 only Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: reversed heapification?
Stefan Behnel wrote: Kent Johnson wrote: heapq.nlargest() heapq.nsmallest() On second thought, that doesn't actually get me very far. I do not know in advance how many I must select since I need to remove duplicates *after* sorting (they are not necessarily 'duplicate' enough to fall into the same sort bucket). What I'd like to do is heapify and then create an iterator for the result. But since heapify doesn't support "reverse" ... Any other ideas? Wrap your data in a class that defines __cmp__ as the inverse of __cmp__ on the underlying data, then use heapq? Just sort the list? Kent Stefan -- http://mail.python.org/mailman/listinfo/python-list
Re: shuffle the lines of a large file
Joerg Schuster wrote: Hello, I am looking for a method to "shuffle" the lines of a large file. I have a corpus of sorted and "uniqed" English sentences that has been produced with (1): (1) sort corpus | uniq > corpus.uniq corpus.uniq is 80G large. The fact that every sentence appears only once in corpus.uniq plays an important role for the processes I use to involve my corpus in. Yet, the alphabetical order is an unwanted side effect of (1): Very often, I do not want (or rather, I do not have the computational capacities) to apply a program to all of corpus.uniq. Yet, any series of lines of corpus.uniq is obviously a very lopsided set of English sentences. So, it would be very useful to do one of the following things: - produce corpus.uniq in a such a way that it is not sorted in any way - shuffle corpus.uniq > corpus.uniq.shuffled Unfortunately, none of the machines that I may use has 80G RAM. So, using a dictionary will not help. There was a thread a while ago about choosing random lines from a file without reading the whole file into memory. Would that help? Instead of shuffling the file, shuffle the users. I can't find the thread though... Kent -- http://mail.python.org/mailman/listinfo/python-list
Re: parameter name conflict. How to solve?
Bo Peng wrote: def func(output=''): output(output=output) Naturally, I get 'str' object is not callable. Is there a way to tell func that the first output is actually a function? (like in C++, ::output(output) ) You could use a default argument: def func(output='', output_fn=output): output_fn(output=output) Kent -- http://mail.python.org/mailman/listinfo/python-list
