Collision Entropy

Problem

Return the collision entropy (Renyi entropy of order 2) in bits:

H2 = -log2(sum(p_i^2))

A larger collision probability means lower entropy.

Hint

The sum of squared probabilities is the probability that two independent draws collide.

case 1

in: [[0.5,0.5]]

expected: 1

case 2

in: [[1]]

expected: 0

case 3

in: [[0.25,0.25,0.25,0.25]]

expected: 2

case 4

in: [[0.5,0.25,0.25]]

expected: 1.415037499278844

Starter codePython

import math
def collision_entropy(probs):
    # Your code here
    pass

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