Question

Can anyone tell me how can I call for indexes in a nested list?

Generally I just write:

for i in range(len(list))

but what if I have a list with nested lists as below:

Nlist = [[2, 2, 2], [3, 3, 3], [4, 4, 4], ...]

and I want to go through the indexes of each one separately?

Answer 1

If you really need the indices you can just do what you said again for the inner list:

l = [[2,2,2],[3,3,3],[4,4,4]]
for index1 in xrange(len(l)):
    for index2 in xrange(len(l[index1])):
        print index1, index2, l[index1][index2]

But it is more pythonic to iterate through the list itself:

for inner_l in l:
    for item in inner_l:
        print item

If you really need the indices you can also use enumerate:

for index1, inner_l in enumerate(l):
    for index2, item in enumerate(inner_l):
        print index1, index2, item, l[index1][index2]