6.7) Nested Lists

A nested list is a list containing a list. We’ve seen examples of list of strings, a list of lists is much the same.

>>> L=[[1,2,3],[4,5,6]]
>>> L[0]  # the first element of L is also a list
[1, 2, 3]
>>> L[1]  # and so is the second element of L
[4, 5, 6]

If you want to refer to the third element of the second list in L:

>>>L[1][2]
6

To remember which index comes first, think of breaking down the process like this:

>>> sublist=L[1]
>>> sublist[2]
6

So you first look for the second list L[1] and then for the third element in that list [2].

See a nested list in action with the Pythontutor.com visualisation tool.

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