On 09/10/06, Robert Kern <[EMAIL PROTECTED]> wrote: > Daniel Mahler wrote: > > In my case all a, b, c are large with b and c being orders of > > magnitude lareger than a. > > b is known to contain only, but potentially any, a-indexes, reapeated > > many times. > > c contains arbitray floats. > > essentially it is to compute class totals > > as in total[class[i]] += value[i] > > In that case, a slight modification to Greg's suggestion will probably be > fastest:
If a is even moderately large and you don't care what's left behind in b and c you will probably accelerate the process by sorting b and c together (for cache coherency in a) This seems like a rather common operation - I know I've needed it on at least two occasions - is it worth creating some sort of C implementation? What is the appropriate generalization? A. M. Archibald ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
