Mailman 3 June 2009 - Tutor

Wave module
by Alex Krycek Feb. 12, 2015

Feb. 12, 2015

Hello, I'm trying to join two .wav files with the wave module. But when I try to use wave.open(filename, "rb") I receive the following error: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "F:\PortablePython1.0\lib\wave.py", line 483, in open return Wave_read(f) File "F:\PortablePython1.0\lib\wave.py", line 162, in __init__ self.initfp(f) File "F:\PortablePython1.0\lib\wave.py", line 143, in initfp self._read_fmt_chunk(chunk) File "F:\PortablePython1.0\lib\wave.py", line 264, in _read_fmt_chunk raise Error, 'unknown format: %r' % (wFormatTag,) wave.Error: unknown format: 85 I read somewhere that there are various wave formats, only some supported by Python. Is this true? If so, is there any way I can convert my wave files into a supported kind? Thanks!

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Send binary/hex data to a TCP socket
by Tod Haren July 19, 2011

July 19, 2011

I need to send a server at the other end of a socket a 36 byte "frame", where each byte represents a specific field in the custom data structure. (If there are any Ham operators reading this, I'm talking about the AGW Packet Engine) The documentation for the server says to initialize each field to a binary zero(0x00). How do I get a binary zero in Python? The next step is to send this all to the server and subsequently receive a similarly formated frame. A very basic frame looks something like this(modified from documentation): |00 00 00 00 4D 00 00 00 00 00 00 00 00 00 00 00 |....M........... |00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................ |00 00 00 00 |.... My problem is that hex(0) return '0x0' and hex(ord('M')) returns '0x4d'. If I concatonate these all together then the socket receives 109 bytes instead of 36. The documentation examples are in C++, so they are little help to me. The examples make use of the MoveMemory function for building the frames, but I'm clueless what that does. Pseudo code for the frame above: l = [] for i in xrange(36): l.append(hex(0)) l[4]=hex(ord('M')) d='' d=d.join(l) #I need some other data type to send besides a string! sock.send(d) #send the 36 bytes to the socket Any pointers or references would be greatly appreciated.

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cx_Oracle help
by Greg Lindstrom Jan. 6, 2011

Jan. 6, 2011

Hello, I'm trying to help out a friend and am stumped. Can you help me out? Thanks, --greg - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I will briefly explain the problem I am facing. I am using Oracle 9.2, Python 2.5 and I installed cx_Oracle- 4.3.1-win32-9i-py25 in Python. From python I tried following : >>> import cx_Oracle >>> myDsn = cx_Oracle.makedsn('ISCN47',1521,'AUBDBS01') >>> CONN = cx_Oracle.connect(myusr, mypwd, myDsn) Traceback (most recent call last): File "<pyshell#4>", line 1, in <module> conn = cx_Oracle.Connection('scott','tiger',myDsn) RuntimeError: Unable to acquire Oracle environment handle I have set the below environment variables too NLS_LANG: <snip>.WE8MSWIN1252 ORACLE_HOME: D:\Tools\oracle\ora92 ORACLE_SID: AUBDBS01 PYTHON_HOME: d:\Utility\Python25 PYTHONPATH: %PYTHON_HOME%\lib;%PYTHON_HOME%\DLLs;%PYTHON_HOME%\Lib\site-packages;%ORACLE_HOME%\bin LD_LIBRARY_PATH: %LD_LIBRARY_PATH%;D:\Tools\oracle\ora92\lib Not getting any idea where I am wrong? Regards, Kishore

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Tracking time
by Michael Key Jan. 6, 2010

Jan. 6, 2010

I am trying to develop a project tracking program that would allow you to track hours and minutes spent on several different projects and store he data in a database for printing. Any help would be appreciated. Mike

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Learning Python
by Fred P Dec. 13, 2009

Dec. 13, 2009

Hey Everyone, I am completely new at python, but not new to programming or scripting. I have a couple of years of LUA scripting experience, about a year of C++ classes, and used to be very efficient at c-shell scripting in unix. My question for you guys: 1) How do I get Started? 2) Recommend any specific Books? 3) Any online tutors/ forums that would benefit a newbie 4) Any online classes that teach python? I have taken online c++ courses, and found them helpful. I was hoping to find something for python. My main objective is to write scripts for the following type of applications File management, file copies/syncs/ compares Text manipulation - like parsing text files to replace or augment specific values Integration into current applications to write redundant routines and maybe some day plugins I am not even sure what else, but I do know that every time i think of something that we need at work, other people say, "That would be a good task for a python script" and I would eventually like to be able to do something about that. Thanks Fred

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Re: [Tutor] Parsing Bible verses
by C or L Smith July 29, 2009

July 29, 2009

Here is something from my toolbox of routines that might be useful for the number ranges: >>> indices('-5--2') [-5, -4, -3, -2] >>> indices('3-4') [3, 4] >>> indices('3-4,10') [3, 4, 10] /chris def indices(s,n=None): #("1-3,7")->1,2,3,7;i("1,-3--1")->1,-3,-2,-1; or (slc,n=None)->slc.start,stop,step [for range(n)] """Return a list of indices as defined by a MSWord print dialog-like range: e.g. "1,3,5-7" -> [1, 3, 5, 6, 7] A trailing comma will be ignored; a trailing dash will generate an error.""" # ranges must be increasing: -3--4 will not generate any numbers assert type(s) is str r=[x.strip() for x in s.split(',')] rv = [] for ri in r: if not ri: continue if ri.find('-',1)>0: #ignore - in first position dashat = ri.find('-',1) #start searching at position 1 nums = ri[:dashat],ri[dashat+1:] #one might want to use sys.maxint-1 for stop if the '-' is encountered, the #meaning being "from start to the end (as defined by the code elsewhere") #but then this should be made into an iterator rather than generating the #whole list if nums[1] in ['','-']: raise ValueError('missing number in request to indices: %s'%ri) start, stop = [int(x.strip()) for x in nums] for i in xrange(start, stop+1): rv.append(i)#yield i else: rv.append(int(ri))#yield int(ri) return rv

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XML: changing value of elements
by Johan Geldenhuys July 16, 2009

July 16, 2009

Hi all, I have a rather complex XML file and I need to change some values inside this file. So far I have been using minidom, but I can't find the thing I am looking for. My code so far: """ from xml.dom import minidom xmlFile = 'signal1.xml' xmlDocument = minidom.parse(xmlFile) SignalsNode = xmlDocument.firstChild signalNode = SignalsNode.childNodes[1] signalNode.removeAttribute("name") signalNode.setAttribute("name", "Test_Name") signalNode.getAttribute("name") descElem = signalNode.childNodes[1] """ I know how to manipulate the value of the attributes, but I can't seem to change the values of eg: "Description" Snippet from my XML file: """ <?xml version="1.0" encoding="UTF-8" ?> <file:///C:\Users\Public\XML%20parse\signal1.xml##> - <Signals> <file:///C:\Users\Public\XML%20parse\signal1.xml##> - <Signal model="Model" name="Model_X" type="Flyer"> <Description>Some description</Description> <SpecName> Model_X </SpecName> <Reporting category="POW" name="" /> <file:///C:\Users\Public\XML%20parse\signal1.xml##> - <Trigger type="open"> <Severity>normal</Severity> <Message>Model X 1</Message> </Trigger> <file:///C:\Users\Public\XML%20parse\signal1.xml##> - <Trigger type="close"> <Severity>minor</Severity> <Message> Model X 2</Message> </Trigger> </Signal> </Signals> """ Any suggestions on how to change some of the values of the elements? Thanks Johan

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cx_oracle module problems
by jeremiah July 7, 2009

July 7, 2009

I've downloaded the cx_oracle source module for python, howerver every time i try to build it, it keeps on failing. I've been unable to find a port for Ubuntu. Is there one? Anyone know how to get this properly installed? # sudo python setup.py install Traceback (most recent call last): File "setup.py", line 36, in <module> oracleHome = os.environ["ORACLE_HOME"] File "/usr/lib/python2.5/UserDict.py", line 22, in __getitem__ raise KeyError(key) KeyError: 'ORACLE_HOME' Link: http://prdownloads.sourceforge.net/cx-oracle/cx_Oracle-4.2.tar.gz?download Thanks, JJ Disclaimer: The information contained in this transmission, including any attachments, may contain confidential information of Panasonic Avionics Corporation. This transmission is intended only for the use of the addressee(s) listed above. Unauthorized review, dissemination or other use of the information contained in this transmission is strictly prohibited. If you have received this transmission in error or have reason to believe you are not authorized to receive it, please notify the sender by return email and promptly delete the transmission.

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creating a dict-like class - asigning variables... this one may take some thought ; )
by John [H2O] July 3, 2009

July 3, 2009

Hello, I am trying to create a class to hold and reference things similar to matlab's structure. ## A class definition to hold things class stuff(object): """ holds stuff """ def __init__(): pass @classmethod def items(cls): stuff = [] for i in cls.__dict__: if i[:1] != '_' and i != 'items': stuff.append((i,cls.__dict__[i])) return stuff Then in my code I would like to be able to do the follow: s = stuff s.cheese = "Brie" s.country = "French" s.age = 2 and so on... In Ipython, as above it does work. Now here is the tricky part. I'm reading in binary data from unformatted Fortan output. My present approach is as follows (recommended suggestions welcome): f2=file(filename,'rb') #Define names and create Dictionary Keys I = {0:'rl0', 1:'ibdate', 2:'ibtime', 3:'version',\ 4:'rl1', 5:'loutstep', 6:'loutaver', 7:'loutsample',\ 8:'rl2', 9:'outlon0', 10:'outlat0', 11:'numxgrid',\ 12:'numygrid', 13:'dxout', 14:'dyout', 15:'rl3', 16:'numzgrid',\ } #define the format for binary reading first part of the header file Dfmt=['i','i','i','13s','2i','i','i','i','2i','f','f','i','i','f','f','2i','i'] if f2: #print filename + ' has been opened' a=[struct.unpack(ft,f2.read(struct.calcsize(ft))) for ft in Dfmt] # Now I want to put them into my stuff class: for j in range(len(a)): cmd = "h.%s = a[%s][0]" % (I[j],j) eval(cmd) But I get an error: eval(cmd) File "<string>", line 1 h.rl0 = a[0][0] ^ SyntaxError: invalid syntax Thoughts? Must be something simpler or more 'pythonic' Thanks! -- View this message in context: http://www.nabble.com/creating-a-dict-like-class---asigning-variables...-th… Sent from the Python - tutor mailing list archive at Nabble.com.

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PYTHONPATH-corrected
by Bob Rea July 1, 2009

July 1, 2009

In working my way through the book on python, I am working in directories for chapers. Now I am on modules, and some are reused in later chapters. I have set up a directory for the modules. How do I add it to my PYTHONPATH? I can use sys.path.append but that only lasts for the session. This is on a suse linux 10 box -- Bob Rea mailto:petard@petard.us http://www.petard.us http://www.petard.us/blog http://www.petard.us/gallery

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