Python - Make pair from two list such that elements are not same in pairs

In this article, we are going to learn how to make pairs from two lists such that no similar elements make a pair. This is useful when you need to create combinations where each pair contains different values.

Using List Comprehension

The most straightforward approach is to use nested list comprehension with a condition to filter out pairs with identical elements ?

# initializing the lists
numbers_1 = [1, 2, 3, 4, 5]
numbers_2 = [5, 8, 7, 1, 3, 6]

# making pairs
result = [(i, j) for i in numbers_1 for j in numbers_2 if i != j]

# printing the result
print(result)

The output of the above code is ?

[(1, 5), (1, 8), (1, 7), (1, 3), (1, 6), (2, 5), (2, 8), (2, 7), (2, 1), (2, 3), (2, 6), (3, 5), (3, 8), (3, 7), (3, 1), (3, 6), (4, 5), (4, 8), (4, 7), (4, 1), (4, 3), (4, 6), (5, 8), (5, 7), (5, 1), (5, 3), (5, 6)]

Using itertools.product()

We can also solve this problem using the itertools.product() method, which creates the Cartesian product of the input lists. We then filter out pairs with identical elements ?

# importing the module
import itertools

# initializing the lists
numbers_1 = [1, 2, 3, 4, 5]
numbers_2 = [5, 8, 7, 1, 3, 6]

# pairs
pairs = itertools.product(numbers_1, numbers_2)

# filtering the pairs
result = [pair for pair in pairs if pair[0] != pair[1]]

# printing the result
print(result)

The output of the above code is ?

[(1, 5), (1, 8), (1, 7), (1, 3), (1, 6), (2, 5), (2, 8), (2, 7), (2, 1), (2, 3), (2, 6), (3, 5), (3, 8), (3, 7), (3, 1), (3, 6), (4, 5), (4, 8), (4, 7), (4, 1), (4, 3), (4, 6), (5, 8), (5, 7), (5, 1), (5, 3), (5, 6)]

Comparison

Conclusion

Both methods effectively create pairs from two lists while excluding identical elements. List comprehension is more memory-efficient and readable for simple cases, while itertools.product() is better for complex Cartesian product operations.