GridMask Masked Ratio

Problem

Compute the actual masked fraction of a GridMask pattern.

Let d = round(tile * ratio); a pixel is masked when (i mod tile) < d and (j mod tile) < d. Return the masked fraction of the H x W image rounded to 4 decimal places.

Test cases

case 1

in: [4,4,2,1]

expected: 1

case 2

in: [4,4,2,0.5]

expected: 0.25

case 3

in: [4,4,2,0]

expected: 0

case 4

in: [3,4,3,1]

expected: 1

Starter codePython

def gridmask_ratio(h, w, tile, ratio):
    # Your code here
    pass

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