Polynomial Design Matrix

Problem

Build the polynomial regression design matrix for a 1D input x and a given degree: each output row is [1, x_i, x_i^2, ..., x_i^degree].

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

Hint

Prepend the bias column of ones, then append powers 1..degree for each value.

case 1

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

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

case 2

in: [[0,2],3]

expected: [[1,0,0,0],[1,2,4,8]]

case 3

in: [[-1,1],2]

expected: [[1,-1,1],[1,1,1]]

case 4

in: [[],2]

expected: []

Starter codePython

def polynomial_design_matrix(x, degree):
    # Your code here
    pass

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