Cartesian Product of Two Lists in Python

In Python, we can get the Cartesian product of two lists easily. The easiest way to obtain the Cartesian product of two lists is with list comprehension.

list1 = ["a", "b", "c"]
list2 = [1, 2, 3]

cartesian_product = [(x,y) for x in list1 for y in list2]

print(cartesian_product)

#Output:
[('a', 1), ('a', 2), ('a', 3), ('b', 1), ('b', 2), ('b', 3), ('c', 1), ('c', 2), ('c', 3)]

You can also use a for loop to get the Cartesian product of two list objects in Python.

list1 = ["a", "b"]
list2 = [1, 2]

def cartesian_product(lst1, lst2):
    result = []
    for x in lst1:
        for y in lst2:
            result.append((x,y))
    return result

print(cartesian_product(list1,list2))

#Output:
[('a', 1), ('a', 2), ('b', 1), ('b', 2)]

Finally, the Python itertools module has a function product() which finds Cartesian products for you.

from itertools import product

list1 = ["a", "b"]
list2 = [1, 2]

print(list(product(list1,list2)))

#Output:
[('a', 1), ('a', 2), ('b', 1), ('b', 2)]

When working with collections of data in Python, the ability to manipulate them and create new collections is very valuable.

One such manipulation is the ability to get the Cartesian product of lists in a new list.

The Cartesian product of two sets A and B is the set of all possible ordered pairs (a, b), where a is in A and b is in B. We can get the Cartesian product between two lists easily with Python.

The easiest way to get the Cartesian product of two lists is with list comprehension.

Below is a simple example of how to find the Cartesian product of two lists in Python using list comprehension.

list1 = ["a", "b", "c"]
list2 = [1, 2, 3]

cartesian_product = [(x,y) for x in list1 for y in list2]

print(cartesian_product)

#Output:
[('a', 1), ('a', 2), ('a', 3), ('b', 1), ('b', 2), ('b', 3), ('c', 1), ('c', 2), ('c', 3)]

Using for Loop to Get Cartesian Product of Lists in Python

We can also use a loop to get the Cartesian product of lists in Python.

By definition, the Cartesian product of two collections of elements are all possible ordered pairs.

We can define a loop easily which will loop over all possible combinations of our lists and create ordered pairs in the form of tuples.

Below is a simple example of how to find the Cartesian product of two lists in Python using iteration.

list1 = ["a", "b"]
list2 = [1, 2]

def cartesian_product(lst1, lst2):
    result = []
    for x in lst1:
        for y in lst2:
            result.append((x,y))
    return result

print(cartesian_product(list1,list2))

#Output:
[('a', 1), ('a', 2), ('b', 1), ('b', 2)]

Using itertools product() Function to Get Cartesian Product of Lists in Python

The itertools module has many great functions which allow us to iterate over collections and perform complex tasks easily.

We can use the itertools product() function to calculate the Cartesian product of lists.

To get the Cartesian product of multiple lists in Python using product(), just pass the lists to the function.

Below is a simple example of how to find the Cartesian product of two lists in Python using itertools and product().

from itertools import product

list1 = ["a", "b"]
list2 = [1, 2]

print(list(product(list1,list2)))

#Output:
[('a', 1), ('a', 2), ('b', 1), ('b', 2)]

Hopefully this article has been useful for you to learn how to get the cartesian product of lists in Python.