[Python-Dev] Re: Candidate Itertools

David Eppstein eppstein at ics.uci.edu
Tue Jun 15 17:54:39 EDT 2004

In article <000a01c452b2$a6f13b20$bfaf2c81 at oemcomputer>,
 "Raymond Hettinger" <raymond.hettinger at verizon.net> wrote:

> Feedback is requested for two prospective itertools:
> def count_elements(iterable):
>     b = {}
>     for elem in iterable:
>         b[elem] = b.get(elem, 0) + 1
>     return ((cnt, elem) for elem, cnt in b.iteritems())
> def pairswap(iterable):
>     return ((b,a) for a,b in iterable)

I'd probably use count_elements, but as Bob I. already said, I'd prefer 
the dict to the transposed pairs of its items.  I'm not so sure why 
pairswap would be better than the generator expression it replaces, 

David Eppstein                      http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science

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