"groupby" is brilliant!

[James Stroud]

Alex Martelli wrote:
> James Stroud <jstroud at ucla.edu> wrote:
>    ...
> 
>>def doit(rows, doers, i=0):
>>   for r, alist in groupby(rows, itemgetter(i)):
>>     if len(doers) > 1:
>>       doit(alist, doers[1:], i+1)
>>     doers[0](r)
> 
> 
> Isn't this making N useless slices (thus copies, for most kinds of
> sequences) for a doers of length N?  Since you're passing i anyway, it
> seems to me that:
> 
> def doit(rows, doers, i=0):
>     for r, alist in groupby(rows, itemgetter(i)):
>       if len(doers) > i+1:
>          doit(alist, doers, i+1)
>       doers[i](r)
> 
> is equivalent to your code, but avoids these slices (thus copies).
> 
> 
> Alex

Yes, it does seem the copies are useless. Thank you.

James

-- 
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/