> The C-code is basically a directy "translation" of the original Python > code. ... > If I had to do it over again, I would place the std implementation there where > it could be appropriately optimized.
Isn't C-code a good place for optimizations? //Torgil On 8/27/06, Travis Oliphant <[EMAIL PROTECTED]> wrote: > Torgil Svensson wrote: > > Hi > > > > ndarray.std(axis=1) seems to have memory issues on large 2D-arrays. I > > first thought I had a performance issue but discovered that std() used > > lots of memory and therefore caused lots of swapping. > > > There are certainly lots of intermediate arrays created as the > calculation proceeds. The calculation is not particularly "smart." It > just does the basic averaging and multiplication needed. > > > I want to get an array where element i is the stadard deviation of row > > i in the 2D array. Using valgrind on the std() function... > > > > $ valgrind --tool=massif python -c "from numpy import *; > > a=reshape(arange(100000*100),(100000,100)).std(axis=1)" > > > > ... showed me a peak of 200Mb memory while iterating line by line... > > > > > The C-code is basically a directy "translation" of the original Python > code. There are lots of temporaries created (apparently 5 at one point > :-). I did this before I had the _internal.py code in place where I > place Python functions that need to be accessed from C. If I had to do > it over again, I would place the std implementation there where it could > be appropriately optimized. > > > > -Travis > > ------------------------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > Numpy-discussion mailing list > Numpy-discussion@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/numpy-discussion > ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
