如何用 Python 来模拟概率

小朋友问我一个问题, 如何用 Python 来模拟概率. 

题目是: 从 [-2, -1, 0, 1, 2, 3] 中随机选择两个不同的数, 乘积为 0 的概率是多少?

我搜索并思考了一下, 得出以下两种方式:

choice_1 的思路是, 对列表进行深拷贝来模拟

choice_2 的思路是, 如果选到相同的数, 就放弃本次选择.

乘积为 0 用 (A1 == 0 or A2 == 0) 来判断, 性能方面可能快一点

 1 import random
 2 import copy
 3 
 4 
 5 def choice_1 (trials):
 6 
 7     total  = 0
 8     number = 0.0
 9 
10     lst = [-2, -1, 0, 1, 2, 3]
11 
12     while total < trials:
13 
14         A1 = random.choice (lst)
15         lstbk = copy.deepcopy (lst)
16         lstbk.remove (A1)
17         A2 = random.choice (lstbk)
18 
19         if (A1 == 0 or A2 == 0):
20             number += 1.0
21 
22         total += 1
23 
24     print (number/total)
25 
26 
27 def choice_2 (trials):
28 
29     total  = 0
30     number = 0.0
31 
32     lst = [-2, -1, 0, 1, 2, 3]
33 
34     while total < trials:
35 
36         A1 = random.choice (lst)
37         A2 = random.choice (lst)
38         if (A1 == A2):
39             continue
40 
41         if (A1 == 0 or A2 == 0):
42             number += 1.0
43 
44         total += 1
45 
46     print (number/total)
47 
48 
49 choice_1 (102400)
50 choice_2 (102400)
51 choice_1 (102400)
52 choice_2 (102400)
53 choice_1 (102400)
54 choice_2 (102400)

输出:

0.335185546875
0.33296875
0.333583984375
0.33208984375
0.332392578125
0.333876953125

思路来自

https://stackoverflow.com/questions/11356036/probability-simulation-in-python