Talk is cheap, show me the code.
random_demo.py代码如下:
# coding: utf-8 import random def random_index(rate): """随机变量的概率函数""" # # 参数rate为list<int> # 返回概率事件的下标索引 start = 0 index = 0 randnum = random.randint(1, sum(rate)) for index, scope in enumerate(rate): start += scope if randnum <= start: break return index def main(): arr = ['red', 'green', 'blue'] rate = [45, 30, 25] red_times = 0 green_times = 0 blue_times = 0 for i in xrange(10000): if arr[random_index(rate)] == 'red': red_times += 1 if arr[random_index(rate)] == 'green': green_times += 1 if arr[random_index(rate)] == 'blue': blue_times += 1 print red_times, green_times, blue_times if __name__ == '__main__': main()打印结果:
$ python random_demo.py 4507 3009 2537 $ python random_demo.py 4586 3055 2485 $ python random_demo.py 4483 2996 2506 $ python random_demo.py 4586 3015 2480 $ python random_demo.py 4513 3057 2415 $ python random_demo.py 4494 3014 2456 $ python random_demo.py 4502 2978 2505 $ python random_demo.py 4475 3041 2528 $ python random_demo.py 4561 3043 2520 $ python random_demo.py 4558 2923 2474 $ python random_demo.py 4536 2957 2535 $ python random_demo.py 4526 2985 2576 $ python random_demo.py 4532 2936 2547 $ python random_demo.py 4420 2908 2447可以看到结果, 抽中红绿蓝的次数非常接近它们的概率比例45:30:25, 其中random_index(rate)函数为核心代码.
OK, Enjoy it~
