Feature Crossing

Problem

Cross two categorical features by concatenating each pair as 'a_b' strings.

Return the crossed list; empty input returns [].

Hint

Convert both values to strings and join them with an underscore.

case 1

in: [["red","blue"],["S","M"]]

expected: ["red_S","blue_M"]

case 2

in: [[1,2],[3,4]]

expected: ["1_3","2_4"]

case 3

in: [["x"],["y"]]

expected: ["x_y"]

case 4

in: [[],[]]

expected: []

Starter codePython

def feature_cross(a, b):
    # Your code here
    pass

4 test cases · run your code against them in the editor