Count of all possible combinations from multiple lists

Question

I have the lists:

list_a = set(["A", "B", "C", "D", "E", "F"])
list_b = set(["1", "2", "3", "4", "5", "6"])
list_c = set(["red", "yellow", "blue", "green"])

I would like to find the total number of possible combinations of these lists (one item per lists)

This is easily possible with smaller lists

import itertools as it

list_set = [list_a, list_b, list_c] 

len(list(it.product(*list_of_unq_vars)))

Which will return the number of combinations.

However for larger lists i run into a memeory error.

Is there a way to calculate the number of possible combinations in this manner without actually creating the combinations themselves (as i have done above)?

Many thanks, J

multiply the number of all items of each list with each other (like @meowgoesthedog pointed out) — Flob, Feb 22 '19 at 15:22
doesn't @meowgoesthedog solves your issue, you mean something else? — com, Feb 22 '19 at 15:27

Hoog · Accepted Answer · 2019-02-22T15:24:28.110

5

All you need to do is multiply the length of each list to get total number of combinations possible:

tempcomb = 1
for l in list_set:
    tempcomb *= len(l)
print(tempcomb)

edited Feb 22 '19 at 15:24

answered Feb 22 '19 at 15:23

Hoog

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Please be a bit more specific with your answer (explain why, what, edit code to actually look like code...) – Flob Feb 22 '19 at 15:24
I dun hit enter too fast... – Hoog Feb 22 '19 at 15:24
right, looking good now ;) – Flob Feb 22 '19 at 15:25

Count of all possible combinations from multiple lists

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