Weighted Random Pick (Seeded)

Problem

Pick a value with probability proportional to its weight using a seeded generator.

Draw r = random.Random(seed).random() times the total weight and return the value whose cumulative weight first exceeds r. If the total weight is not positive return None.

Return the chosen value.

Hint

Walk the cumulative sums until the cumulative weight passes r.

Test cases

case 1

in: [["a","b"],[1,3],1]

expected: "a"

case 2

in: [["a","b"],[1,3],2]

expected: "b"

case 3

in: [["x"],[5],7]

expected: "x"

case 4

in: [["a","b","c"],[0,0,1],3]

expected: "c"

case 5

in: [[],[],0]

expected: null

Starter codePython

def weighted_random_pick(values, weights, seed):
    # Your code here
    pass

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