[Python-Dev] tally (and other accumulators) (original) (raw)

Raymond Hettinger python at rcn.com
Tue Apr 4 20:26:17 CEST 2006

[Alex]

This is quite general and simple at the same time: for example, it was proposed originally to answer some complaint about any and all giving no indication of the count of true/false items:

tally(bool(x) for x in seq) would give a dict with two entries, counts of true and false items.

FWIW, sum() works nicely for counting true entries:

>>> sum(x%3==0 for x in range(100))

34

Raymond

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