Question

Say I have several lists

A = [1,2,3]
B = [4,5,6]
C = [7,8,9]

How can I create new lists so that they contain matching indexes, as in:

D = [1,4,7]
E = [2,5,8]
F = [3,6,9]

The original lists will always contain the same number of elements, and I need this to work for any number of elements and any number of lists, not just three. I figure I need to loop over a range, but I’m not sure how to go about it.

Answer 1

If I understand you correctly, you may be looking for zip():

>>> a = [1, 2, 3]
>>> b = [4, 5, 6]
>>> c = [7, 8, 9]
>>> zipped = zip(a, b, c)
>>> zipped
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]

If instead of several lists, you have a list of the lists that you want to zip, then you can use * for unpacking the sublists, as follows:

>>> myListOfLists = [[1,2,3],[4,5,6],[7,8,9]]
>>> zipped = zip(*myListOfLists)
>>> zipped
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]