for_some(), for_all()?

Larry Bates lbates at swamisoft.com
Wed Sep 22 19:04:05 CEST 2004


Use list comprehension and then test for what you want:

for_some

result=[x for x in lst if <insert your test here>]

if result:
    #
    # At least some of the items passed the test
    #
else:
    #
    # None passed
    #

for_all

result=[x for x in lst if <insert your test here>]

if len(result) == len(lst):
    #
    # All items passed the test
    #
else:
    #
    # At least one didn't pass
    #

I think it is easier to read and maintain.

Larry Bates





"aurora" <aurora00 at gmail.com> wrote in message 
news:opseqmpvg86yt6e7 at news.cisco.com...
>I am trying to test a list to see if some or all elements pass a test. For 
>example I can use reduce() to test if any element is 0.
>
>>>> lst = [1,2,0,3]
>>>> test = lambda x: x == 0
>>>> reduce(operator.__or__,[test(x) for x in lst])
> True
>
> However I bet reduce() does not exploit the short circuit logic. Also it 
> is a little clumsy to create another list to pass into reduce. Is there 
> some equivalent of
>
>   for_some(test, lst)
> or
>   for_all(test, lst)?
>
> 





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