Em Sáb, 2006-04-01 às 08:35 -0800, Steve R. Hastings escreveu:
> def tally(seq, d=None):
> if d == None:
> d = {}
>
> for x in seq:
> if x in d:
> d[x] += 1
> else:
> d[x] = 1
> return d
Two changes:
- Use "is None".
- Use "try ... except" instead of "in"
def tally2(seq, d=None):
if d is None:
d = {}
for x in seq:
try:
d[x] += 1
except KeyError:
d[x] = 1
return d
It's also faster:
>>> from random import choice
>>> a = []
>>> for i in xrange(100000):
... a.append(choice([False, True]))
...
>>> tally(a)
{False: 49922, True: 50078}
>>> tally2(a)
{False: 49922, True: 50078}
>>> from timeit import Timer
>>> min(Timer(stmt='b=tally(a)', setup='from __main__ import a,
tally').repeat(3, 100))
4.2756481170654297
>>> min(Timer(stmt='b=tally2(a)', setup='from __main__ import a,
tally2').repeat(3, 100))
3.812028169631958
Maybe you don't like my version, and the gains aren't that much, but
please use "is None" instead of "== None".
Cheers,
--
Felipe.
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