Diagonal Matrix from Vector

Problem

Build the n x n diagonal matrix whose diagonal is the vector v.

Return D with D[i][j] = v[i] if i == j and 0 otherwise.

Hint

This is the inverse operation of extracting the main diagonal.

case 1

in: [[1,2,3]]

expected: [[1,0,0],[0,2,0],[0,0,3]]

case 2

in: [[5]]

expected: [[5]]

case 3

in: [[0,0]]

expected: [[0,0],[0,0]]

case 4

in: [[1.5,-2.5]]

expected: [[1.5,0],[0,-2.5]]

Starter codePython

def diag_matrix(v):
    # Your code here
    pass

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