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  • Getting Started with Python: Attribute Error

    - by Nacari
    I am new to python and just downloaded it today. I am using it to work on a web spider, so to test it out and make sure everything was working, I downloaded a sample code. Unfortunately, it does not work and gives me the error: "AttributeError: 'MyShell' object has no attribute 'loaded' " I am not sure if the code its self has an error or I failed to do something correctly when installing python. Is there anything you have to do when installing python like adding environmental variables, etc.? And what does that error generally mean? Here is the sample code I used with imported spider class: import chilkat spider = chilkat.CkSpider() spider.Initialize("www.chilkatsoft.com") spider.AddUnspidered("http://www.chilkatsoft.com/") for i in range(0,10): success = spider.CrawlNext() if (success == True): print spider.lastUrl() else: if (spider.get_NumUnspidered() == 0): print "No more URLs to spider" else: print spider.lastErrorText() # Sleep 1 second before spidering the next URL. spider.SleepMs(1000)

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  • ungetc in Python

    - by Dragos Toader
    Some file read (readlines()) functions in Python copy the file contents to memory (as a list) I need to process a file that's too large to be copied in memory and as such need to use a file pointer (to access the file one byte at a time) -- as in C getc(). The additional requirement I have is that I'd like to rewind the file pointer to previous bytes like in C ungetc(). Is there a way to do this in Python? Also, in Python, I can read one line at a time with readline() Is there a way to read the previous line going backward?

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  • Reverse Engineer a .pyo python file

    - by Brian
    I have 2 .pyo python files that I can convert to .py source files, but they don't compile perfectly as hinted by decompyle's verify. Therefore looking at the source code, I can tell that config.pyo simply had variables in in an array: ADMIN_USERIDS = [116901, 141, 349244, 39, 1159488] I would like to take the original .pyo and disassembly or whatever I need to do inorder to change one of these IDs. Or.... in model.pyo the source indicates a if (productsDeveloperId != self.getUserId()): All I would want to do is hex edit the != to be a == .....Simple with a windows exe program but I can't find a good python disassembler anywhere. Any suggestions are welcomed...I am new to reading bytecode and new to python as well.

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  • Python: Why is IDLE so slow?

    - by Adam Matan
    Hi, IDLE is my favorite Python editor. It offers very nice and intuitive Python shell which is extremely useful for unit-testing and debugging, and a neat debugger. However, code executed under IDLE is insanely slow. By insanely I mean 3 orders of magnitude slow: bash time echo "for i in range(10000): print 'x'," | python Takes 0.052s, IDLE import datetime start=datetime.datetime.now() for i in range(10000): print 'x', end=datetime.datetime.now() print end-start Takes: >>> 0:01:44.853951 Which is roughly 2,000 times slower. Any thoughts, or ideas how to improve this? I guess it has something to do with the debugger in the background, but I'm not really sure. Adam

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  • Python (windows) will open files from command line, but not from a script launched from eclipse

    - by Blake
    I'm pretty new to writing python for windows (linux is no problem), and am having problems getting python to recognize files when running scripts, though it behaves fine in the command line What am I doing wrong here? def verifyFile(x): # return os.path.isfile(x) This will return true (with a valid file, of course) when called from the python command line, but when I run the script from eclipse, or launch it from windows, it ALWAYS returns false. Any thoughts on why this is? I've tried passing pathnames like this: D:\Documents and Settings\BDE\Desktop\cdburn.jpg and like this: D:/Documents and Settings/BDE/Desktop/cdburn.jpg I've changed sys,argv[0] to '' I've tried this: def verifyFile(x): # try: f = open(x, 'r') f.close() return True except: return False and am getting no love! Any help would be appreciated. Thanks Blake

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  • How do I use Python's itertools.groupby()?

    - by James Sulak
    I haven't been able to find an understandable explanation of how to actually use Python's itertools.groupby() function. What I'm trying to do is this: take a list - in this case, the children of an objectified lxml element - divide it into groups based on some criteria, and then later iterate over each of these groups separately. I've reviewed the documentation (http://docs.python.org/lib/itertools-functions.html), and the examples, (http://docs.python.org/lib/itertools-example.html), but I've had trouble trying to apply them beyond a simple list of numbers. So, how do I use of itertools.groupby()? Is there another technique I should be using? Pointers to good "prerequisite" reading would also be appreciated.

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  • AES Encryption. From Python (pyCrypto) to .NET

    - by Why
    I am currently trying to port a legacy Python app over to .NET which contains AES encrpytion using from what I can tell pyCrpyto. I have very limited Python and Crypto experience. The code uses the snippet from the following page. http://www.djangosnippets.org/snippets/1095/ So far I believe I have managed to work out that it that it calls Crypto.Cipher with AES and the first 32 character of our secret key as the password, but no mode or IV. It also puts a prefix on the encrpyed text when it is added to database. What I can't work out is how I can decrypt the existing ecrypted database records in .NET. I have been looking at RijndaelManaged but it requires an IV and can't see any reference to one in python. Can anyone point me in the dirrection to what method could be used in .NET to get the desired result.

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  • Pre-generating GUIDs for use in python?

    - by rjuiaa1
    I have a python program that needs to generate several guids and hand them back with some other data to a client over the network. It may be hit with a lot of requests in a short time period and I would like the latency to be as low as reasonably possible. Ideally, rather than generating new guids on the fly as the client waits for a response, I would rather be bulk-generating a list of guids in the background that is continually replenished so that I always have pre-generated ones ready to hand out. I am using the uuid module in python on linux. I understand that this is using the uuidd daemon to get uuids. Does uuidd already take care of pre-genreating uuids so that it always has some ready? From the documentation it appears that it does not. Is there some setting in python or with uuidd to get it to do this automatically? Is there a more elegant approach then manually creating a background thread in my program that maintains a list of uuids?

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  • deciding between subprocess, multiprocesser and thread in Python?

    - by user248237
    I'd like to parallelize my Python program so that it can make use of multiple processors on the machine that it runs on. My parallelization is very simple, in that all the parallel "threads" of the program are independent and write their output to separate files. I don't need the threads to exchange information but it is imperative that I know when the threads finish since some steps of my pipeline depend on their output. Portability is important, in that I'd like this to run on any Python version on Mac, Linux and Windows. Given these constraints, which is the most appropriate Python module for implementing this? I am tryign to decide between thread, subprocess and multiprocessing, which all seem to provide related functionality. Any thoughts on this? I'd like the simplest solution that's portable. Thanks.

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  • how to install mysqlDb for MySQL and Python ON WINDOWS

    - by Spikie
    I AM A NET DEVELOPER TRY TO INSTALL MYSQLDB FOR PYTHON I KEEP HAVING THIS ERROR MESSAGE raise ImproperlyConfigured("Error loading MySQLdb module: %s" % e) django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module: No module named MySQLdb I AM FOLLOWING THIS INSTRUCTION FROM THIS SITE <"http://sourceforge.net/project/shownotes.php?release_id=303257" I DO NOT UNDERSTAND THESE LINES Windows ....... C:... python setup.py install C:... python setup.py bdist_wininst The latter example should build a Windows installer package, if you have the correct tools. In any event, you must have a C compiler. Additionally, you have to set an environment variable (mysqlroot) which is the path to your MySQL installation. In theory, it would be possible to get this information out of the registry, but like I said, I don't do Windows, but I'll accept a patch that does this. I HAVE BEEN SEARCHING FOR ANSWER ALL DAY PLEASE DO ANYBODY REALLY KNOW HOW TO DO THIS OR AT LEAST POINT ME IN THE RIGHT DIRECTION???? THANKS and what is the c compiler for???????

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  • Installing bitarray in Python 2.6 on Windows

    - by John Fouhy
    I would like to install bitarray in Windows running python 2.6. I have mingw32 installed, and I have C:\Python26\Lib\distutils\distutils.cfg set to: [build] compiler = mingw32 If I type, in a cmd.exe window: C:\Documents and Settings\john\My Documents\bitarray-0.3.5>python setup.py install I get: [normal python messages skipped] C:\MinGW\bin\gcc.exe -mno-cygwin -mdll -O -Wall -IC:\Python26\include -IC:\Python26\PC -c bitarray/_bitarray.c -o build\temp.win32-2.6\Release\bitarray\_bitarray.o bitarray/_bitarray.c:2197: error: initializer element is not constant bitarray/_bitarray.c:2197: error: (near initialization for `BitarrayIter_Type.tp_getattro') bitarray/_bitarray.c:2206: error: initializer element is not constant bitarray/_bitarray.c:2206: error: (near initialization for `BitarrayIter_Type.tp_iter') bitarray/_bitarray.c:2232: error: initializer element is not constant bitarray/_bitarray.c:2232: error: (near initialization for `Bitarraytype.tp_getattro') bitarray/_bitarray.c:2253: error: initializer element is not constant bitarray/_bitarray.c:2253: error: (near initialization for `Bitarraytype.tp_alloc') bitarray/_bitarray.c:2255: error: initializer element is not constant bitarray/_bitarray.c:2255: error: (near initialization for `Bitarraytype.tp_free') error: command 'gcc' failed with exit status 1 Can anyone help?

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  • Python Bitstream implementations

    - by Danielb
    I am writing a huffman implementation in Python as a learning exercise. I have got to the point of writing out my variable length huffman codes to a buffer (or file). Only to find there does not seem to be a bitstream class implemented by Python! I have had a look at the array and struct modules but they do not seem to do what I need without extra work. A bit of goggling turned up this bitstream implementation, which is more like what I am wanting. Is there really no comparable bitstream class in the Python standard library?

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  • problems importing ttk from tkinter in python 2.7

    - by Benjimin Boyce
    I'm working with an example file in a tutorial that asks me to first do two imports: from tkinter import * from tkinter import ttk I get an error. I researched a bit and found that in python 2.7.x I need to capitalize the 't'in tkinter, so I change to: from Tkinter import * from Tkinter import ttk. the first line no longer gives and error, but I still get error: ImportError: cannot import name ttk. I have researched this issue on this site and other places, and cannot seem to understand what this ttk is. I'm further confused by the fact that, when I go to the python interpreter, and I type "help()", then "modules", and then "ttk" it seems to know what it is, and gives me a lot of description, for example: "DESCRIPTION This module provides classes to allow using Tk themed widget set." -however, python won't let me import it.

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  • Inaccurate Logarithm in Python

    - by Avihu Turzion
    I work daily with Python 2.4 at my company. I used the versatile logarithm function 'log' from the standard math library, and when I entered log(2**31, 2) it returned 31.000000000000004, which struck me as a bit odd. I did the same thing with other powers of 2, and it worked perfectly. I ran 'log10(2**31) / log10(2)' and I got a round 31.0 I tried running the same original function in Python 3.0.1, assuming that it was fixed in a more advanced version. Why does this happen? Is it possible that there are some inaccuracies in mathematical functions in Python?

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  • python xml.dom.minidom.Attr question

    - by rudy
    Getting attributes using minidom in Python, one uses the "attributes" property. e.g. node.attributes["id"].value So if I have <a id="foo"></a>, that should give me "foo". node.attributes["id"] does not return the value of the named attribute, but an xml.dom.minidom.Attr instance. But looking at the help for Attr, by doing help('xml.dom.minidom.Attr'), nowhere is this magic "value" property mentioned. I like to learn APIs by looking at the type hierarchy, instance methods etc. Where did this "value" property come from?? Why is it not listed in the Attr class' page? The only data descriptors mentioned are isId, localName and schemaType. Its also not inherited from any superclasses. Since I'm new to Python, would some of the Python gurus enlighten?

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  • Parallelism in Python

    - by fmark
    What are the options for achieving parallelism in Python? I want to perform a bunch of CPU bound calculations over some very large rasters, and would like to parallelise them. Coming from a C background, I am familiar with three approaches to parallelism: Message passing processes, possibly distributed across a cluster, e.g. MPI. Explicit shared memory parallelism, either using pthreads or fork(), pipe(), et. al Implicit shared memory parallelism, using OpenMP. Deciding on an approach to use is an exercise in trade-offs. In Python, what approaches are available and what are their characteristics? Is there a clusterable MPI clone? What are the preferred ways of achieving shared memory parallelism? I have heard reference to problems with the GIL, as well as references to tasklets. In short, what do I need to know about the different parallelization strategies in Python before choosing between them?

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  • What Python based Dashboard options exist?

    - by stuartcw
    I want to create a Dashboard on each server to show it's health and the results of some daily processing. I plan to hook up shell scripts and Python programs to collect the data. Instead of writing a web-based interface, I thought it would be good to use a python based web dashboard that could render the results in various business user and manager friendly formats. What are my options to do this? I am primarily interested in Python RedHat Linux, but other platforms are interesting too. I'm also open to Perl and Ruby based solutions especially if the plugins can be language neutral.

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  • How to prevent traffic to/from a slow Cassandra node using Python

    - by Sergio Ayestarán
    Intro: I have a Python application using a Cassandra 1.2.4 cluster with a replication factor of 3, all reads and writes are done with a consistency level of 2. To access the cluster I use the CQL library. The Cassandra cluster is running on rackspace's virtual servers. The problem: From time to time one of the nodes can become slower than usual, in this case I want to be able to detect this situation and prevent making requests to the slow node and if possible to stop using it at all (this should theoretically be possible since the RF is 3 and the CL is 2 for every single request). The questions: What's the best way of detecting the slow node from a Python application? Is there a way to stop using one of the Cassandra nodes from Python in this scenario without human intervention? Thanks in advance!

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  • Check if key is pressed using python (a daemon in the background)

    - by Nazarius Kappertaal
    I've created a python script in which an event needs to be executed each time I press the Super (or WinKey) on my keyboard. How can one achieve this without the python process being "focused" - as it is running in the background waiting for the key to be pressed to execute the event? I've seen a lot of posts around the web showing me how to read input - but they have all required one to have the process "focused" and none have showed me how to capture the Super (or WinKey) using a python script. I'm running Ubuntu 9.10.

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  • Named semaphores in Python?

    - by Boaz
    Hi, I have a script in python which uses a resource which can not be used by more than a certain amount of concurrent scripts running. Classically, this would be solved by a named semaphores but I can not find those in the documentation of the multiprocessing module or threading . Am I missing something or are named semaphores not implemented / exposed by Python? and more importantly, if the answer is no, what is the best way to emulate one? Thanks, Boaz PS. For reasons which are not so relevant to this question, I can not aggregate the task to a continuously running process/daemon or work with spawned processed - both of which, it seems, would have worked with the python API.

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  • Query size of block device file in Python

    - by ??O?????
    Hello. I have a Python script that reads a file (typically from optical media) marking the unreadable sectors, to allow a re-attempt to read said unreadable sectors on a different optical reader. I discovered that my script does not work with block devices (e.g. /dev/sr0), in order to create a copy of the contained ISO9660/UDF filesystem, because os.stat().st_size is zero. The algorithm currently needs to know the filesize in advance; I can change that, but the issue (of knowing the block device size) remains, and it's not answered here, so I open this question. I am aware of the following two related SO questions: Determine the size of a block device (/proc/partitions, ioctl through ctypes) how to check file size in python? (about non-special files) Therefore, I'm asking: in Python, how can I get the file size of a block device file?

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  • Paver 0.8.1 compatibility with python 2.6

    - by Bertrand
    Hi, Does anyone manage to bootstrap its development area using paver with python 2.6 ? I have install python 2.6, install paver with easy_install-2.6, everything looks fine. But when I try to launch the bootstrap method it raises an urllib2.HTTPError (: HTTP Error 404: Not Found) while trying to download http://pypi.python.org/packages/2.6/s/setuptools/setuptools-0.6c8-py2.6.egg. I have tryed to add the correct setuptools EGG file (which is 0.6c9) in the support-files directory, bootstrap.py find the EGG file, but doesn't seem to use it because it still try to download the 0.6c8 version which is no more available. Any ideas how to solve this issue ? Thanks in advance Bertrand

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  • Python Pari Library?

    - by silinter
    Pari/GP is an excellent library for functions relating to number theory. The problem is that there doesn't seem to be an up to date wrapper for python anywhere around, (pari-python uses an old version of pari) and I'm wondering if anyone knows of some other library/wrapper that is similar to pari or one that uses pari. I'm aware of SAGE, but it's far too large for my needs. GMPY is excellent as well, but there are some intrinsic pari functions that I miss, and I'd much rather use python than the provided GP environment. NZMATH, mpmath, scipy and sympy were all taken into consideration as well. On a related note, does anyone have any suggestions on loading the pari dll itself and using the functions contained in it? I've tried to very little success, other than loading it and learning about function pointers.

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  • Python os.path.join

    - by Jim
    Hello, I am trying to learn python and am making a program that will output a script. I want to use os.path.join but am pretty confused (I know I am very bad at scripting/programming) See, according to the docs ( http://docs.python.org/library/os.path.html ) if I say os.path.join('c:', 'sourcedir') I get C:sourcedir as it's output. According to the docs, this is normal (right?) But when I use the copytree command, Python will output it the desired way, for example import shutil src = os.path.join('c:', 'src') dst = os.path.join('c':', 'dst') shutil.copytree(src, dst) Here is the error code I get WindowsError: [Error 3] The system cannot find the path specified: 'C:src/.' If I wrap the os.path.join with os.path.normpath I get the same error If this os.path.join can't be used this way, then I am confused as to its purpose According to the pages suggested by Stack Overflow, slashes should not be used in join--that is correct I assume? Thanks guys(girls) for your help

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  • Unicode identifiers in Python?

    - by viksit
    Hi all, I want to build a Python function that calculates, and would like to name my summation function S. In a similar fashion, would like to use ? for product, and so on. I was wondering if there was a way to name a python function in this fashion? def S (..): .. .. That is, does Python support unicode identifiers, and if so, could someone provide an example for it? Thanks! Original motivation for this was a piece of Clojure code I saw today that looks like, (defn entropy [X] (* -1 (S [i X] (* (p i) (log (p i)))))) where S is a macro defined as, (defmacro S ... ) and I thought that was pretty cool.

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