[Python-Dev] function for counting items in a sequence
brett at python.org
Sun Apr 8 03:31:31 CEST 2007
On 4/7/07, Steven Bethard <steven.bethard at gmail.com> wrote:
> On 4/7/07, Steven Bethard <steven.bethard at gmail.com> wrote:
> > Here's a patch implementing collections.counts() as suggested above:
> > http://bugs.python.org/1696199
> > Example usage, from the docstring::
> > >>> items = 'acabbacba'
> > >>> item_counts = counts(items)
> > >>> for item in 'abcd':
> > ... print item, item_counts[item]
> > ...
> > a 4
> > b 3
> > c 2
> > d 0
> Guido commented in the tracker that it would be worth discussing
> whether that last item (``item_counts['d']``) should return 0 (as a
> defaultdict would) or raise KeyError (as a dict would).
> Anyone have a good motivation for one approach or the other?
I say 0 if it is really meant to represent a count as the absense of
something is 0. The object returned is being viewed as an object
representing the count of items, not specifically as a dict.
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