Asking for Help

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Questions

• How (aside from reading gobs and gobs of source code) can I find out the asymptotic time behaviour of various primitive Python operations? For example, for list xs, does xs.append(x) take amortized O(1) time or O(n) time?
• ssl-1.14.tar.gz exists and supposedly works with Python 2.5x. Assuming I have Visual Studio .NET 2003 available on my box, how do I build the package for Windows. It currently complains about a series of openssl *.h files that aren't available. I can drag in openssl for www.openssl.org, but which version, if that is applicable, and how do I connect the two either in a directory structure or appropriate configuration files?

• I want to use ElementTree to parse a text object, but the ElementTree.parse function looks like it only takes file objects. I'm doing this all from within Blender, and don't want to touch the filesystem - so is there a way to create a file object from text (to pass to parse) without touching the file system? I'd also like to go the other way, create a text object from an ElementTree object.

• I'm working with embedding Python into my applications. However, the Py_Initialize() is producing an " 'import site' failed " message on non-dev computers. I was wondering if there is a way to fix this or is it just a bug with Python? Thank you.
• I'm trying to run the IDLE but it wont go on. i have an R52 leptop with ibm-tools installed (there is ver 2.2 there but i changed it so it wont ebe the default one). im trying to run ver 2.6. Thank
• I'm new to python and I am just working with the idle-shell. How can I write a script without having python executing orders immediately after I type them into the shell? Follow-Up question: Having written the script, how do I run it in the interpreter?

• I just installed MacPython. Unfortunately it doesn't seem to include the CoreGraphics-Python Module. Where ist my old system python? How can I uninstall MacPython?

• Is there any way to get the environment from a subprocess.Popen created by python? In other words, if the new process updates it's environment, is it possible to get access to the modifications. For example In my case I'm executing MS Visual Studio's vsvars32.bat file and would like to access the modified PATH environment variable.
• Is there any way to determine if the C implementation under my Python uses IEEE 754 for floating point numbers? If yes, what is it?
• I am trying to run Python script in ABAQUS, but there is a error "Import Error: No Module named " Tkinter"". So how can I handle the problem? Thanks

• Why do I call constructor of Cmd class in my Cmd subclass __init__ method?

• When I import Tkinter, Python exits. Why?

Longer Questions

Pages containing longer questions should appear in a list below.

These questions will be moved to the section below when they are added to the CategoryAskingForHelpAnswered category (upon being answered, hopefully).

Answered (fully or partially)

• How can I add or substract two to the last digit of a float? Like 4.9999 should be 5.0001 or 4.9997. The problem is

   >>> 4.9999
   4.9999000000000002
   would yield 4.9999000000000000 or 4.9999000000000004 which is not right.
   I could make a str(4.9999), convert each character to an int and work on each character from right   
   to left, but there must be a better way.
   this is not what I want as well:
   >>> ( 4.9999 * 10000 + 2 ) / 10000.0
   5.0000999999999998 -> this should be 5.0001
   this makes it somehow :))
   >>> str(( 4.9999 * 10000 + 2 ) / 10000)
   '5.0001'

  http://www.python.org/doc/current/library/decimal.html?highlight=round#decimal-faq

• How do I write multi-line strings in doctest tests?

• How do I get / set the modification date of a file?

• How do I use gzip module with pickle?

• How can "normal" users report bugs in Python or the documentation?

• How can I convert a hex representation to an integer?

• SubtractionQuestion

• Related question to the for-a-blink question in the answered section. When running os.system(some command) the CMD.exe window pops up and then terminates when the process terminates. How do I get the contents of what was in that CMD.exe window saved someplace - variable, file, etc. Variable assignment doesn't work - only the exit code is in the variable.

  • Seems to me you need to redirect the stdout. As per Python Library Reference 6.1.5., this is impossible for os.system() calls.
• Does anyone know why msOffice products (using win32com return) u'dana\u2019s best' rather than u'dana's best'?

  • Microsoft Office replaces apostrophes (U+0027) with "Right Single Quotation Marks" (U+2019) automatically. While this looks correct typograpphically, it might cause some problems. -- IanBollinger

• I'm a total Python newbie. How do I get Python started on a Palm handheld ( http://c2.com/cgi/wiki?PalmPython ) ? Or should I focus on learning Python on a desktop PC first ? -- DavidCary

  • I would recommend learning Python on a normal desktop system, with a recent version, a full suite of libraries, and IPython (Interactive Python) installed. After you've learned the basics then you can probably adapt more readily to the limitations of the Palm Pilot interface, implementation, version (older), and libraries (reduced subset). JimD

• How do you save python code and use it for anything? --elpenmaster

  • Save it as "scriptName.py" and then execute it with the Python interpreter. As for choosing a purpose for the code, that's entirely up to you. -- PeytonMcCullough

    • How do I save it as scriptname.py? --elpenmaster
      • - it is possible to enter python commands into a text file, rather than entering them directly into the python shell. Simply create a text file containing your python instructions and save it as scriptname.py, you can then import it into a python shell session or execute it directly.

• TestHarnessDesign -- I've been assigned the task of designing a test harness for embedded systems, servers and software. -- JimD

• How do I publish Python modules?

  • See PublishingPythonModules - Philip, 2005-09-19

    lwickjr: My question, "my" page. I created that page, empty, in hopes that someone would populate it. They have, and I've read it. They hadn`t yet when I created *this* page for posting how-to questions, at about the same time, so I included the question here in the seed page. See the attachments to my page for my final solution to the problem. By the way, "How to publish Python modules" has been renamed "PublishingPythonModules", to be more Wiki-style. [Me, again.] 2005-11-24.

• i got winxp. i make a simple program like print "hello". i save it as whatever.py. then i double-click it. nothing happens just the windows cmd appears for a blink. Additionally you can go to Start -> Run, type 'cmd', and hit enter. Now cd to your foo.py file, and execute it.

  • The Windows command window appears "for a blink" to show the output ("hello") before going away again - your program ends and the window closes. You can, of course, run the program from the command window (type "python whatever.py") to see the output, or you could make the program pause (using time.sleep) or wait for input (raw_input) before finishing - that would at least leave the command window open. Some operating systems leave command windows open after the program has finished, by the way.

• This is an actual question. I have have a prototype for a python related website. Right now I am just running it off old PC (http://66.32.187.134). Where could I host this site & and do you think this site would be helpful to the advancement of Python programming knowledge? Thanks. Father Jack

  • Father Jack, you should look at the PythonHosting page and consider some of the options presented there. Your site doesn't seem to be available, so it's hard to assess what its contribution to Python programming knowledge might be. -- PaulBoddie

• How can I programming the io ports (eg.: LPT) with Python?

  • Have you tried using the pyParallel module? -- DavidBoddie

  I am new at python, I have python 2.5 and every time i open the shell python resets my moniter to 800x600. How do I keep python from messing with my monitor settings? -Travis

• I wish to generate graphics and images directly into a file, but I'm confused as to just what i need to do this with python

• How can I run an untrusted Python script safely (i.e. Sandbox)

• Socket module changed in Python 2.5?

• "I come from a java background. Java has an API that list all classes and their methods that come with Java. Is there anything like that in python?"

• "How can I truly "protect" the python source code we create for a commercial product?"

• "Where can I find a tiny python installation (under 2 MB) for an embedded linux system?"

• "How do I use local variables in a function within a class? (I do not want to use self.x, as this makes the instance have variables. I want variables local to my function, that get destroyed at the end of it.) I can only think of using del at the end of the function, is there a better way?"

• PythonFramework-x.x.pkg installation fails. Is there a workaround?

• I'm trying to split a string, but without breaking the quotes

  x = '"a,b", c, d, "e,f,h", "i,j,k"'
  re.sub('"([^"]*)"', "\g<1>", x) 
  -> 'a,b, c, d, e,f,h, i,j,k' # Ok for me
  
  re.sub('"([^"]*)"', "|\g<1>|", x)
  -> '|a,b|, c, d, |e,f,h|, |i,j,k|'   # To show the separation of the groups, also Ok
  
  re.sub('"([^"]*)"', "\g<1>".replace(",", "|"), x)
  -> 'a,b, c, d, e,f,h, i,j,k' # The same result!
  -> 'a|b, c, d, e|f|h, i|j|k' # It doesn't suppose to replace all "," with "|" like here?

  • No, it is doing what you told it to do. To realize this you must know that arguments are evaluated before they are passed to the functions. But what is the value of "\g<1>".replace(",", "|")? "\g<1>", of course, as there are no commas to replace in "\g<1>". re.sub therefore receives '"([^"]*)"' and "\g<1>" as arguments, which is the exact equivalent of the first call.

• How to store information in variable arrays?

• How do I run Python based software from SourceForge?

• I am new to Python from Java background, I have following structure

  /root
          /folder1
                  Class1.py
                  Class2.py
          /folder2
                  Class3.py

  I am in the folder2 and want to run class3.py but it need to import a module from Class1.py Could someone please help me?
  • I believe you just need to add folder1 to your path variable. Should be something along the lines of...

       1 import sys
       2 sys.path.append('/root/folder1')
       3 import Class1
    

    If that doesn't work, look through the documentation for info on how the sys.path variable works -- I may just have the syntax slightly off
• I was browsing the Python source code, trying to find out how str.strip() is implemented as a string method. I found string.py in the Lib directory, but that didn't seem to hold the answer. Could you please help me learn where to look?

  • Take a look in the Objects directory for built-in types. The stringobject.c file contains the implementations of string methods, and the string_strip function should provide some details of the underlying functions used to provide the strip method's functionality.

Answered Longer Questions

Pages containing answered longer questions should appear in a list below.

Questions appear here when they are added to the CategoryAskingForHelpAnswered category.

CategoryFaq