Gal Diskin schrieb:
> Hi,
> I am writing a code that needs to iterate over 3 lists at the same
> time, i.e something like this:
>
> for x1 in l1:
> for x2 in l2:
> for x3 in l3:
> print "do something with", x1, x2, x3
>
> What I need to do is go over all n-tuples where the first argument is
> from the first list, the second from the second list, and so on...
Heard about recursion?
def collect(L,*lists):
if not lists:
return [(x,) for x in L]
collection = []
for x in L:
for y in collect(lists[0],*lists[1:]):
collection.append((x,)+y)
return collection
for item in collect( l1, l2, l3):
func(*item)
Here is the same in generator form
def collect(L,*lists):
if not lists:
for x in L:
yield (x,)
else:
for x in L:
for y in collect(lists[0],*lists[1:]):
yield (x,)+y
( o.k - it required two nested for-loops in each implementation :)
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