Quadratic Features

Problem

Build degree-2 polynomial features for a single variable: each row is [x_i, x_i^2].

Return the list of rows; empty input returns [].

Hint

Emit the original value and its square for each input.

case 1

in: [[1,2,3]]

expected: [[1,1],[2,4],[3,9]]

case 2

in: [[-2,0,2]]

expected: [[-2,4],[0,0],[2,4]]

case 3

in: [[0.5]]

expected: [[0.5,0.25]]

case 4

in: [[]]

expected: []

Starter codePython

def quadratic_features(x):
    # Your code here
    pass

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