There's a specific package for arrays http://www.stsci.edu/resources/software_hardware/numarray
that implements array mathematics. I use it for pixel map manipulation in pygame, so it's relatively fast. On Mon, 31 Jan 2005 19:09:59 +0100, Gregor Lingl <[EMAIL PROTECTED]> wrote: > Hi all of you, > > I'm representing a 4x4 matrix as a 16-element list, e.g. > > m=range(16) > > first 4 elements first row, second four elements second row etc. > I want to sum rows and columns like > > i-th row: > > sum(m[4*i:4*i+4]) > > and ith column: > > sum(m[i::4]) > > This seems to be slow because of the formation of the slices. > I wonder if there is a way using generators or generator-expressions > (which I didn't study yet) to compute these sums without copying > parts of the matrix to a new list. (I'd guess that there should exist > some canonical generator for sequences, which produces their elements > ..., maybe also for slices ?) > > All comments, hints, solutions are welcome. > > Regards, > Gregor > > -- > Gregor Lingl > Reisnerstrasse 3/19 > A-1030 Wien > > Telefon: +43 1 713 33 98 > Mobil: +43 664 140 35 27 > > Autor von "Python für Kids" > Website: python4kids.net > _______________________________________________ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor > -- 'There is only one basic human right, and that is to do as you damn well please. And with it comes the only basic human duty, to take the consequences. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
