reduce expression to test sublist
Hi All The following reduce expression checks if every element of list lst1 is present in list lst2. It works as expected for integer lists but for lists of strings, it always returns False. reduce( lambda x,y: (x in lst2) and (y in lst2), lst1) Moreover, for the lists of strings the following for-loop gives correct results when the above reduce expression doesn't. isSublist = True for i in lst1: isSublist = isSublist and (i in lst2) if not isSublist: isSublist = False break Can someone help me understand why? Asim -- http://mail.python.org/mailman/listinfo/python-list
Re: Sorting Large File (Code/Performance)
On Jan 24, 4:26 pm, [EMAIL PROTECTED] wrote: > Thanks to all who replied. It's very appreciated. > > Yes, I had to doublecheck line counts and the number of lines is ~16 > million (insetead of stated 1.6B). > > Also: > > >What is a "Unicode text file"? How is it encoded: utf8, utf16, utf16le, > >utf16be, ??? If you don't know, do this: > > The file is UTF-8 > > > Do the first two characters always belong to the ASCII subset? > > Yes, first two always belong to ASCII subset > > > What are you going to do with it after it's sorted? > > I need to isolate all lines that start with two characters (zz to be > particular) > > > Here's a start:http://docs.python.org/lib/typesseq-mutable.html > > Google "GnuWin32" and see if their sort does what you want. > > Will do, thanks for the tip. > > > If you really have a 2GB file and only 2GB of RAM, I suggest that you don't > > hold your breath. > > I am limited with resources. Unfortunately. > Since the OP has stated that they are running Windows XP, and more than one poster has suggested installing more RAM in the box, I thought people should know that WinXP has certain limitations on the amount of memory that may be used: http://msdn2.microsoft.com/en-us/library/aa366778.aspx Firstly, the maximum amount of physical memory that may be installed is 4GB. Secondly, with the "4 gigabyte tuning" and "IMAGE_FILE_LARGE_ADDRESS_AWARE" patches, the maximum amount of virtual memory (phyical memory + swapfile size) that may be assigned to user processes is 2GB. Hence, even if you made a 100GB swap file with 4GB RAM installed, by default only a maximum of 2GB would ever be assigned to a user- process. With the two flags enabled, the maximum becomes 3GB. If the OP finds performance to be limited and thinks more RAM would help trying a later version of Windows would be a start, but better would be to try Linux or Mac OSX out. Cheers, Asim > Cheers, > > Ira -- http://mail.python.org/mailman/listinfo/python-list
Re: Sorting Large File (Code/Performance)
On Jan 25, 9:23 am, Asim <[EMAIL PROTECTED]> wrote: > On Jan 24, 4:26 pm, [EMAIL PROTECTED] wrote: > > > > > Thanks to all who replied. It's very appreciated. > > > Yes, I had to doublecheck line counts and the number of lines is ~16 > > million (insetead of stated 1.6B). > > > Also: > > > >What is a "Unicode text file"? How is it encoded: utf8, utf16, utf16le, > > >utf16be, ??? If you don't know, do this: > > > The file is UTF-8 > > > > Do the first two characters always belong to the ASCII subset? > > > Yes, first two always belong to ASCII subset > > > > What are you going to do with it after it's sorted? > > > I need to isolate all lines that start with two characters (zz to be > > particular) > > > > Here's a start:http://docs.python.org/lib/typesseq-mutable.html > > > Google "GnuWin32" and see if their sort does what you want. > > > Will do, thanks for the tip. > > > > If you really have a 2GB file and only 2GB of RAM, I suggest that you > > > don't hold your breath. > > > I am limited with resources. Unfortunately. > > Since the OP has stated that they are running Windows XP, and more > than one poster has suggested installing more RAM in the box, I > thought people should know that WinXP has certain limitations on the > amount of memory that may be used: > > http://msdn2.microsoft.com/en-us/library/aa366778.aspx > > Firstly, the maximum amount of physical memory that may be installed > is 4GB. Secondly, with the "4 gigabyte tuning" and > "IMAGE_FILE_LARGE_ADDRESS_AWARE" patches, the maximum amount of > virtual memory (phyical memory + swapfile size) that may be assigned > to user processes is 2GB. > > Hence, even if you made a 100GB swap file with 4GB RAM installed, by > default only a maximum of 2GB would ever be assigned to a user- > process. With the two flags enabled, the maximum becomes 3GB. > > If the OP finds performance to be limited and thinks more RAM would > help trying a later version of Windows would be a start, but better > would be to try Linux or Mac OSX out. > > Cheers, > Asim > > > Cheers, > > > Ira Sorry, just to clarify my response. Any 32-bit OS will only be able to assign 4GB of virtual memory to a single processes, the argument being that since processes can only issue 32-bit instructions the process can only address a maximum of 2^32 bytes of addresses (assuming the architecture is using byte-addressed memory). Another link that's easier to grok: http://www.codinghorror.com/blog/archives/000811.html However, a 32-bit OS may support more than 4GB of virtual memory (using "Physical Address Extension", or PAE) and split it more intelligently between processes than Windows XP or Vista does: http://www.ibm.com/developerworks/linux/library/l-memmod/ So allocating more than 4GB of virtual memory to your sort application could be achieved through splitting your task into more than one process on an appropriate OS. AFAIK, such memory limitations are dependent on the particular Linux distro you're using, and I'm not sure about Mac OSX limitations. This applies doubly for 64-bit architectures and OS's. Please correct me, with references, if my conclusions are wrong. Cheers, Asim -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythons & Ladders
On Feb 28, 9:10 pm, Jeff Schwab <[EMAIL PROTECTED]> wrote: > Benoit wrote: > > Forgive my language concerning C++ as its turned the thread into > > something I did not intend. I merely wished to point out that Python > > was easier for me to learn than C++. To Schwab, its likely that Mark > > Lutz is simply a better instructor than my professor. > > Sorry for hijacking your thread! > > In addition to Python Challenge, check out Code Golf: > > http://codegolf.com/ > > It's eye-opening to see how concise the solutions can be. You should also give Project Euler a shot: http://projecteuler.net/index.php?section=problems Just keep in mind two points. One, your solutions should work with under one minute of execution time, even in Python. Secondly, the main benefit of the site is attempting some of the simpler problems and then diving head-first into the forums to see other peoples' solutions to the same problem. I guarantee you'll find some unique Python techniques from these forums that should open new avenues of learning wrt Python for you. Nothing enterprise level...but definitely interesting. Be warned that some of the harder problems require undergraduate-level math. -- http://mail.python.org/mailman/listinfo/python-list
Re: Ideal way to separate GUI and logic?
On Mon, Jul 15, 2013 at 5:25 PM, wrote: > Again, thanks for all the responses. I'm curious, though, what exactly is > the rationale for making functions so small? (I've heard that the function > calling of Python has relatively high overhead?) > There is a small overhead, but it makes the code easier to read and understand. You can look at the function name and get and idea of _what_ the function is doing instead of having to figure out _how_ it is doing it. Regarding optimization, after you have written your application if you see performance issues you can surgically optimize the spots that have the issues and leave most of the code untouched. To quote Don Knuth, "premature optimization is the root of all evil". Also the article at http://en.wikipedia.org/wiki/Program_optimization makes some good points. -- http://mail.python.org/mailman/listinfo/python-list
Re: GDAL installation
Hi Leo,
This might be a PATH issue.
See this discussion for details.
https://pythongisandstuff.wordpress.com/2011/07/07/installing-gdal-and-ogr-for-python-on-windows/
Asim
On Tue, Feb 10, 2015 at 9:11 PM, Leo Kris Palao wrote:
> Hi Python Users,
>
> I currently installed the Python 2.7.9 and installed the GDAL package.
> First, I tried to install GDAL using PIP but it throws an error - I cannot
> remember the exact error message. So, I install it using easy_install
> command. But when I import the package I am getting this message, which I
> really don't understand.
>
> Microsoft Windows [Version 6.1.7601]
> Copyright (c) 2009 Microsoft Corporation. All rights reserved.
>
> C:\Users\lpalao>python
>> Python 2.7.9 (default, Dec 10 2014, 12:28:03) [MSC v.1500 64 bit (AMD64)]
>> on win32
>> Type "help", "copyright", "credits" or "license" for more information.
>> >>> import gdal
>> Traceback (most recent call last):
>> File "", line 1, in
>> File "C:\Python27\Python2.7.9\lib\site-packages\gdal.py", line 2, in
>>
>> from osgeo.gdal import deprecation_warn
>> File "C:\Python27\Python2.7.9\lib\site-packages\osgeo\__init__.py",
>> line 21, in
>> _gdal = swig_import_helper()
>> File "C:\Python27\Python2.7.9\lib\site-packages\osgeo\__init__.py",
>> line 17, in swig_import_helper
>> _mod = imp.load_module('_gdal', fp, pathname, description)
>> ImportError: DLL load failed: The specified module could not be found.
>> >>>
>
>
> Thanks in advance,
> -Leo
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
>
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