🌐 Mailman 3 January 2003 - Python-list - python.org

Sine wave?
by EC Nov. 25, 2013

Nov. 25, 2013

Ive been banging my head against the wall for the past few days trying to generate a sine wave... My math skills arent the best, I'll admit, and I think I'm going crosseyed trying to understand this... I *think* the following code should work but it outputs some really weird stuff. I'm sorta new so please help if you can! Thank you Eric #------------------------------------------- import math import wave import string pi = math.pi sin = math.sin cos = math.cos #init output and related vars sr = 44100 Outfile = wave.open("outfile.wav", "w") Outfile.setnchannels(1) Outfile.setsampwidth(4) Outfile.setframerate(sr) Outfile.setcomptype("NONE", "Uncompressed") Outtemp = [] Outstr = "" def get_phase(curphs, freq): phinc = (freq*1.0000/sr*1.0000)*360 phase = curphs + phinc if phase >= 360: phase -= 360 elif phase < 0: phase += 360 return phase def gen_wav(sec, freq, ampcent): numsamp = sec*sr amp = (ampcent*1.0000/100)*32767 i = 0 temp = [] t = 0 curphase = 0 while i < numsamp: curphase = get_phase(curphase, freq) t = int(round(amp*sin(2*pi*curphase))) temp.append(t) i+=1 return temp Outtemp = gen_wav(.01, 440, 75) Outstr = string.join(map(str, Outtemp), ",") print Outstr Outfile.writeframes(Outstr) Outfile.close()

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mutlifile inheritance problem
by maurelius01＠hotmail.com Sept. 21, 2013

Sept. 21, 2013

I have classes defined in different files and would like to inherit from a class in file A.py for a class in file B.py but am running into problems. I'm using Python 1.5.2 on Windows NT Here's a specific example: ************************ file cbase01.py: class CBase: def __init__(self): self.cclass = None print "cbase" class CImStream(CBase): def __init(self): CBase.__init__(self) print "CImStream" ************************* in file wrappers_A01.py: import cbase01 reload(cbase01) class ImStream_SavedBitmaps(cbase01.CImStream): def __init__(self): cbase.CImStream.__init__(self) print "SavedBitmaps" ************************** in file sequencer01.py import cbase01 # the offending lines, program works reload(cbase01) # if I comment these out. class Sequencer: def Append(self, item): pass ***************************** in test02.py import wrappers_A01 reload(wrappers_A01) import sequencer01 reload(sequencer01) x0 = wrappers_A01.ImStream_SavedBitmaps() *************************************************************** If I run test02 I get the traceback Traceback (innermost last): File "<string>", line 1, in ? File "D:\PythonCode\pna\eyeTracking\tests\test02.py", line 15, in ? x0 = wrappers_A01.ImStream_SavedBitmaps() File "D:\PythonCode\pna\eyeTracking\tests\wrappers_A01.py", line 21, in __init__ cbase.CImStream.__init__(self) TypeError: unbound method must be called with class instance 1st argument Any ideas what I am doing wrong? Thanks, Marc

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Weirdness with python and stdin redirection under Win32
by Jonathan M. Gilligan Jan. 18, 2013

Jan. 18, 2013

I am getting an error reading stdin only when I invoke a python script by typing "bar | foo.py" or "foo.py < bar", but not when typing "bar | python foo.py" or "python foo.py < bar". The error arises ecause when input is redirected, stdin has fileno = -1 if the script is invoked as "foo.py", but correctly has fileno = 0 if it is invoked as "python foo.py" Consider the following script, which I want to use as a prototype for a simple stdin --> stdout filter: # foo.py import sys print "fileno = ", sys.stdin.fileno() lines = sys.stdin.xreadlines() for line in lines: sys.stdout.write(line) On win32 (Win2k pro, SP3), using ActiveState ActivePython 2.2.1 build 222, I can execute foo.py either by typing "foo.py" or "python foo.py" on the command line (the relevant registry key for opening .py files has command 'C:\Python22\python.exe "%1" %*'). If I type "echo bar | foo.py", I get C:\>echo bar | foo.py The process tried to write to a nonexistent pipe. fileno = -1 Traceback (most recent call last): File "C:\foo.py", line 7, in ? lines = sys.stdin.readlines() IOError: [Errno 9] Bad file descriptor whereas if I type "echo bar | python foo.py", I get C:\>echo bar | python foo.py fileno = 0 bar Other tests yield: C:\>foo.py < foo.py fileno = -1 Traceback (most recent call last): File "C:\Documents and Settings\Jonathan\My Documents\Programming\Omap VU\Fast CameraDriver\BF_LabView\Leo\foo.py", line 7, in ? for line in lines: IOError: [Errno 9] Bad file descriptor C:\>python foo.py < foo.py fileno = 0 # foo.py import sys print "fileno = ", sys.stdin.fileno() lines = sys.stdin.xreadlines() for line in lines: sys.stdout.write(line) If I just type "foo.py" or "python foo.py" on the command line, I get "fileno = 0" in both cases and the script works identically in both cases. Can anyone explain what's happening? Why the file descriptor for redirected stdin has a fileno of -1 if the python script is invoked using "foo.py" but not when it's invoked with "python foo.py"? Thanks, Jonathan

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PyXML 0.8.2 is released
by martin＠v.loewis.de July 17, 2012

July 17, 2012

Version 0.8.2 of the Python/XML distribution is now available. It should be considered a beta release, and can be downloaded from the following URLs: http://prdownloads.sourceforge.net/pyxml/PyXML-0.8.2.tar.gz http://prdownloads.sourceforge.net/pyxml/PyXML-0.8.2.win32-py2.2.exe http://prdownloads.sourceforge.net/pyxml/PyXML-0.8.2-2.2.Suse81.i386.rpm Changes in this version, compared to 0.8.1: * Updated to Expat 1.95.6. * Support more DOM L3 features in minidom: isWhitespaceInElementContent, schemaType, isId, DOMImplementationSource * Various bug fixes, including - 609641: minidom nodes not pickleable - 618156: Use character references in XMLGenerator if necessary - 622286: marshal.wddx: 'recordset' element typo - 624420: Can't create 2nd Sax2.Reader - 665486: Implement SAX skippedEntity for Expat The Python/XML distribution contains the basic tools required for processing XML data using the Python programming language, assembled into one easy-to-install package. The distribution includes parsers and standard interfaces such as SAX and DOM, along with various other useful modules. The package currently contains: * XML parsers: Pyexpat (Jack Jansen), xmlproc (Lars Marius Garshol), sgmlop (Fredrik Lundh). * SAX interface (Lars Marius Garshol) * minidom DOM implementation (Paul Prescod, others) * 4DOM and 4XPath from Fourthought (Uche Ogbuji, Mike Olson) * Schema implementations: TREX (James Tauber) * Various utility modules and functions (various people) * Documentation and example programs (various people) The code is being developed bazaar-style by contributors from the Python XML Special Interest Group, so please send comments and questions to <xml-sig(a)python.org>. Bug reports may be filed on SourceForge: http://sourceforge.net/tracker/index.php?group_id=6473&atid=106473 For more information about Python and XML, see: http://www.python.org/topics/xml/ -- Martin v. Löwis http://www.informatik.hu-berlin.de/~loewis

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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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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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Win32 drive mapping... aka "net use"
by lshuler＠my-deja.com March 5, 2005

March 5, 2005

Is there an API using Win32 extensions to map a drive share? I have not found one yet and have tried searching "Win32 map drive". I am looking for the equivalent of: net use <share path> If not, is there an alternative other than making a call to system("net use <path>"). Thanks in advance, Lance Sent via Deja.com http://www.deja.com/ Before you buy.

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Gate Oxide thickness of CMOS
by hasi＠rediffmail.com Jan. 2, 2005

Jan. 2, 2005

Hi, I would like to know the following details for a CMOS 1.gate oxide thickness 2.The Number of masks 3.Number of transistors per chip Thanks, Hasi!

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Parsing apache log files
by Fernando Rodr�guez Dec. 21, 2004

Dec. 21, 2004

Is there any module for parsing apache log files? O:-) I guess it could be done with regular expressions, but I'm not very gifted with them... :-) ----------------------- Fernando Rodriguez

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Blank ASP pages
by python Dec. 10, 2004

Dec. 10, 2004

My server is spitting out blank .asp pages which use python. If Python is not declared, the asp pages work fine. I just yesterday stepped up to Python 1.52 and the new win32all After the install, the blanks started appearing. All the paths look fine in registry. Any clues? ( Intel dual PIII 550 Xeon, 1G RAM, NT 4.0 SP 6a, IIS 4) ************************************************** Jason S. Nadler Lead Programmer Channel21 Productions, Inc. ... What are you doing right now? **************************************************

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