🌐 Mailman 3 May 2006 - Python-list - python.org

AIX installation can't find zlib
by Larry Whitley Nov. 3, 2011

Nov. 3, 2011

I've just installed the 1.5.2 source distribution on an AIX system and when I say "import zlib" it responds: >>> import zlib Traceback (innermost last): File "<stdin>", line 1, in ? ImportError: No module named zlib >>> I'm not sure where zlib is supposed to be. It's not in the Lib subdirectory of Python-1.5.2. In the Modules subdirectory I find zlibmodule.c. Nothing germaine in the Objects subdirectory. Looked at config.log and config.status, no mention of zlib. Looking at the sys.path I see: .../ldw/Python-1.5.2> python Python 1.5.2 (#1, Jul 26 2000, 14:21:56) [C] on aix4 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> import sys >>> sys.path ['', '/.../rchland.ibm.com/fs/u1/ldw/Projects/Programs/wtCache', '/.../rchland.ibm.com/fs/u1/ldw/Python-1.5.2/Lib/', '/.../rchland.ibm.com/fs/u1/ldw/Python-1.5.2/Lib/plat-aix4', '/.../rchland.ibm.com/fs/u1/ldw/Python-1.5.2/Lib/lib-tk', '/.../rchland.ibm.com/fs/u1/ldw/Python-1.5.2/Modules'] >>> Any suggestions? Larry

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smtplib "authentication required" error
by carl.reimann＠gmail.com May 17, 2008

May 17, 2008

In using a simple smtp routine: # begin example >>> import smtplib >>> server = smtplib.SMTP('outgoing.verizon.net') >>> server.sendmail('my(a)address.net', 'another(a)address.net', """To: another(a)address.net From: my(a)address.net Subject: Shakespeare Quote Tis like the breath of an unfeed lawyer... """) >>> server.quit() # end example I find the following error: raise SMTPSenderRefused(code, resp, from_addr) smtplib.SMTPSenderRefused: (550, '5.7.1 Authentication Required', 'myuserid(a)verizon.net') I have attempted to incorporate into the interactive session: server.login = ('userid', 'password') # the same ones I use in my email program But I get the same error result. My objective is to have a simple way to send email from the command line. To do this I will write a script which can read in a file and send it to the address on top of the file. What is the procedure for authentication? Using the KMail email program (Linux, KDE desktop), I send mail through my Verizon account. Under the Configure KMail / Accounts / Modify Account / Extras tab, I clicked "Check what the server supports" and it came back 'no encryption' and 'cleartext'. So it doesn't seem that it would involve complex procedures. Any help welcome.

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Why can't timedeltas be divided?
by Dan Bishop April 27, 2008

April 27, 2008

If I try to write something like: num_weeks = time_diff / datetime.timedelta(days=7) I get: TypeError: unsupported operand type(s) for /: 'datetime.timedelta' and 'datetime.timedelta' Of course, one could extend the timedelta class to implement division, def _microseconds(self): return (self.days * 86400 + self.seconds) * 1000000 + self.microseconds def __truediv__(self, other): if isinstance(other, datetime.timedelta): return self._microseconds() / other._microseconds() else: return datetime.timedelta(0, 0, self._microseconds() / other) def __floordiv__(self, other): if isinstance(other, datetime.timedelta): return self._microseconds() // other._microseconds() return NotImplemented but why is a basic arithmetic operation missing from the standard datetime module?

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do design patterns still apply with Python?
by John Salerno Jan. 27, 2008

Jan. 27, 2008

Since Python does so many things different, especially compared to compiled and statically typed languages, do most of the basic design patterns still apply when writing Python code? If I were to read a design pattern book (such as Head First Design Patterns), could I apply their Java examples to Python easily enough, or does Python require a different perspective when applying patterns?

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TopSort in Python?
by Tim Peters Jan. 21, 2008

Jan. 21, 2008

From: "Tim Peters" <tim_one(a)email.msn.com> [Dinu C. Gherman] > Does anybody have a simple-minded-but-working full-Python > implementation of topsort, the topological sorting algorithm? > Or maybe *any* topsort? I remember only one such algorithm... > python.org/search doesn't reveal any... Searching for "topological" instead turns up two hits there, a few more on DejaNews. Apparently "the std" algorithm I posted years ago predates DejaNews, though. So here's a fancier version ... check-out-aaron's-kjbuckets-too-ly y'rs - tim # topsort takes a list of pairs, where each pair (x, y) is taken to # mean that x <= y wrt some abstract partial ordering. The return # value is a list, representing a total ordering that respects all # the input constraints. # E.g., # topsort( [(1,2), (3,3)] ) # may return any of (but nothing other than) # [3, 1, 2] # [1, 3, 2] # [1, 2, 3] # because those are the permutations of the input elements that # respect the "1 precedes 2" and "3 precedes 3" input constraints. # Note that a constraint of the form (x, x) is really just a trick # to make sure x appears *somewhere* in the output list. # # If there's a cycle in the constraints, say # topsort( [(1,2), (2,1)] ) # then CycleError is raised, and the exception object supports # many methods to help analyze and break the cycles. This requires # a good deal more code than topsort itself! from exceptions import Exception class CycleError(Exception): def __init__(self, sofar, numpreds, succs): Exception.__init__(self, "cycle in constraints", sofar, numpreds, succs) self.preds = None # return as much of the total ordering as topsort was able to # find before it hit a cycle def get_partial(self): return self[1] # return remaining elt -> count of predecessors map def get_pred_counts(self): return self[2] # return remaining elt -> list of successors map def get_succs(self): return self[3] # return remaining elements (== those that don't appear in # get_partial()) def get_elements(self): return self.get_pred_counts().keys() # Return a list of pairs representing the full state of what's # remaining (if you pass this list back to topsort, it will raise # CycleError again, and if you invoke get_pairlist on *that* # exception object, the result will be isomorphic to *this* # invocation of get_pairlist). # The idea is that you can use pick_a_cycle to find a cycle, # through some means or another pick an (x,y) pair in the cycle # you no longer want to respect, then remove that pair from the # output of get_pairlist and try topsort again. def get_pairlist(self): succs = self.get_succs() answer = [] for x in self.get_elements(): if succs.has_key(x): for y in succs[x]: answer.append( (x, y) ) else: # make sure x appears in topsort's output! answer.append( (x, x) ) return answer # return remaining elt -> list of predecessors map def get_preds(self): if self.preds is not None: return self.preds self.preds = preds = {} remaining_elts = self.get_elements() for x in remaining_elts: preds[x] = [] succs = self.get_succs() for x in remaining_elts: if succs.has_key(x): for y in succs[x]: preds[y].append(x) if __debug__: for x in remaining_elts: assert len(preds[x]) > 0 return preds # return a cycle [x, ..., x] at random def pick_a_cycle(self): remaining_elts = self.get_elements() # We know that everything in remaining_elts has a predecessor, # but don't know that everything in it has a successor. So # crawling forward over succs may hit a dead end. Instead we # crawl backward over the preds until we hit a duplicate, then # reverse the path. preds = self.get_preds() from random import choice x = choice(remaining_elts) answer = [] index = {} in_answer = index.has_key while not in_answer(x): index[x] = len(answer) # index of x in answer answer.append(x) x = choice(preds[x]) answer.append(x) answer = answer[index[x]:] answer.reverse() return answer def topsort(pairlist): numpreds = {} # elt -> # of predecessors successors = {} # elt -> list of successors for first, second in pairlist: # make sure every elt is a key in numpreds if not numpreds.has_key(first): numpreds[first] = 0 if not numpreds.has_key(second): numpreds[second] = 0 # if they're the same, there's no real dependence if first == second: continue # since first < second, second gains a pred ... numpreds[second] = numpreds[second] + 1 # ... and first gains a succ if successors.has_key(first): successors[first].append(second) else: successors[first] = [second] # suck up everything without a predecessor answer = filter(lambda x, numpreds=numpreds: numpreds[x] == 0, numpreds.keys()) # for everything in answer, knock down the pred count on # its successors; note that answer grows *in* the loop for x in answer: assert numpreds[x] == 0 del numpreds[x] if successors.has_key(x): for y in successors[x]: numpreds[y] = numpreds[y] - 1 if numpreds[y] == 0: answer.append(y) # following "del" isn't needed; just makes # CycleError details easier to grasp del successors[x] if numpreds: # everything in numpreds has at least one predecessor -> # there's a cycle if __debug__: for x in numpreds.keys(): assert numpreds[x] > 0 raise CycleError(answer, numpreds, successors) return answer

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fun with unicode files
by Thomas Heller May 19, 2007

May 19, 2007

I want to use ConfigParser with both NT4-style .reg files, which are ascii (or ansi?) files, and XP-stype .reg files which seem to be UTF-16 encoded unicode-files (hope that's the correct terminology). [And yes, I have read the warning in the manual that ConfigParser doesn't interpret the value-type prefixes in the reg files] Here's the start of the method I wrote to detect the encoding and read the file: def _parse_regfile(self, filename): ifi = open(filename, "r") import codecs, StringIO if ifi.read(2) in (codecs.BOM_LE, codecs.BOM_BE): ifi.close() ifi = codecs.open(filename, "r", "utf-16") I wonder: do I really have to check for the BOM manually, or is there a Python function which does that? Continuing the code: # ConfigParser calls .readline(), but: # NotImplementedError: '.readline() is not implemented for UTF-16' # so we need to put the data into a StringIO instance. # Um, cStringIO doesn't handle unicode correctly, so we'll have # to use the slower StringIO ifi = StringIO.StringIO(ifi.read()) ifi.readline() # skip the first two lines ifi.readline() c = ConfigParser() c.readfp(ifi) return c Is there a better way to do this? Why doesn't the UTF-16 codec implement readline()? Thomas

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Uninstall speed with Python 2.4 MSI
by David Bolen May 19, 2007

May 19, 2007

Although it isn't often necessary, I tend to be in the habit of uninstalling Python before updating to new minor releases, or especially during the alpha/beta cycle. I'm in the process of uninstalling 2.4a2 to install 2.4a3 and the uninstall is running absolutely dog slow and burning 100% cpu while doing it (all going to mshta.exe). Watching the progress bar it almost seems to be doing a whole bunch of operations per file or something. The mshta process went away after the removal so I don't believe there was any other scripting running on my system simultaneously. It probably took 5+ minutes for the removal. I can't recall if removing 2.4a1 was like this, but certainly the non-MSI versions weren't, even when all the docs were separate files. I was wondering if anyone else has experience this? I may not have the fastest system at the moment, but this has to have been one of the slowest (proceeeding, if not absolute time) uninstalls I've done in a long while. -- David

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Re: LRU cache (and other things missing from the standard library ...)
by Evan Prodromou March 30, 2007

March 30, 2007

Gerhard, I agree that LRU caches are a data structure too frequently re-implemented in Python. I'd also like to see a "standard" cache package, either as part of the standard library or elsewhere. To that end, I've just uploaded an LRU cache package to the Python Package Index: http://www.python.org/pypi?:action=display&name=lrucache&version=0.2 Please, let me know if there are features you'd need from a cache class that aren't present, implementation improvements that could be made, or what have you. I'm working on a version 0.3 that includes a transparent cache wrapper and LRU memoization for functions. ~ESP -- Evan Prodromou .O. http://bad.dynu.ca/~evan/ ..O evan(a)bad.dynu.ca OOO

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Embedding Matplotlib images into wxPython
by dr_tyson＠hotmail.com Oct. 27, 2006

Oct. 27, 2006

I am trying to embed images into a wxPython app (created using Boa Constructor), but have not been able to do so. I know how to embed plots, but images seem to be a problem. I've tried using code analogous to the example given at the Matplotlib website to no avail. If anybody has been successful at this could you please post some sample code? That would be greatly appreciated. Thanks! Randy

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screen capture
by py Sept. 29, 2006

Sept. 29, 2006

I need to take a screen shot of the computer screen. I am trying to use PIL and I saw there is ImageGrab...however it only works on Windows. Is there a platform-independent ability to work around this? thanks

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