All possible permutations of a set of lists in Python

Question

In Python I have a list of n lists, each with a variable number of elements. How can I create a single list containing all the possible permutations:

For example

Answer 1

You can do it with a multi-level list comprehension:

>>> L1=['a','b','c']
>>> L2=['d']
>>> L3=['e','f']
>>> [[i,j,k] for i in L1 for j in L2 for k in L3]
[['a', 'd', 'e'], ['a', 'd', 'f'], ['b', 'd', 'e'], ['b', 'd', 'f'], ['c', 'd', 'e'], ['c', 'd', 'f']]