文字列のN割をランダムにマスキング

randmask.py

# -*- coding:utf-8 -*- 
import random


def main(text, n): 
    length = len(text)
    count = int(length * n / 10) 
    sample = random.sample(range(length), count)
    L = list(text)
    for i in sample:
        L[i] = '*' 
    return ''.join(L)


if __name__ == '__main__':
    print main('bird in the hand is worth two in the bush', 3)