Imagine having a list (d) that is made of other lists with different lengths. We want to create a new list that looks like the result bellow. But obviously in this case everything is clear, we have a, b and c so we can create nested loops.
a = [1, 2]
b = [10, 20]
c = [100, 200, 300]
d = [a, b, c]
ret = []
for a1 in a:
for b1 in b:
for c1 in c:
ret.append([a1, b1, c1])
print ret
Which results in this:
[[1, 10, 100], [1, 10, 200], [1, 10, 300], [1, 20, 100], [1, 20, 200], [1, 20, 300], [2, 10, 100], [2, 10, 200], [2, 10, 300], [2, 20, 100], [2, 20, 200], [2, 20, 300]]
What if we only have d with unknown number of lists in which there are unknown number of elements like bellow?
d = [[1, 2, 3], [10], [100, 200, 300, 400]]
What you want is itertools.product:
import itertools
a = [1, 2]
b = [10, 20]
c = [100, 200, 300]
d = [a, b, c]
ret = list(itertools.product(a, b, c)) # Or list(itertools.product(*d))