Make ordered pairs from two lists in Python

Question

Suppose I have two lists: a = [1, 2] and b = [3, 4, 5].

What is the Python way of making tuples (1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5)?

Have you tried *anything at all*? `for i in a: for j in b: ...`??? — juanpa.arrivillaga, Mar 20 '21 at 21:03
Does this answer your question? [Cartesian product of two lists in python](https://stackoverflow.com/questions/52192855/cartesian-product-of-two-lists-in-python) — Janez Kuhar, Mar 20 '21 at 21:05

score 3 · Answer 1 · answered Mar 20 '21 at 21:04

3

[(x, y) for x in a for y in b]

gives you [(1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5)]

answered Mar 20 '21 at 21:04

orangecat

246
1
5

score 1 · Answer 2 · answered Mar 20 '21 at 21:07

1

Check itertools.product() which is the exact equivalent code of the answer provided by @orangecat but it returns as iterator.

So if you want list of these you can just do the following:

  output = list(itertools.product(a, b))

answered Mar 20 '21 at 21:07

the23Effect

580
2
7

score 1 · Accepted Answer · answered Mar 20 '21 at 21:07

When the lists are bigger and u don't want to manually add all the for steps in a list comprehension u can use itertools, for example:

from itertools import product

a = [1, 2]
b = [3, 4, 5]

result = list(product(a, b))
print(result)
>>> [(1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5)]

Make ordered pairs from two lists in Python

3 Answers3