How to Flatten a List of Lists in Python

Given a matrix represented as a list of lists in Python, you can flatten it into a one-dimensional list using a simple method. For example, if you have the following matrix:

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

You can flatten this matrix into a single list using a magic methodlist comprehensionconditional expression:

[item for row in matrix for rowitem in itemrow]

Running this code will create a flattened list [1, 2, 3, 4, 5, 6, 7, 8, 9].