订单号首位按概率生成

随机100w订单统计的成功结果：

fst_char_oid count(*)
1	10
2	193
3	228
4	2227
5	5605
6	1834

目的：按照这种规律生成订单号的首位 注：总数10097，5开头的5605，占总数的55.6%

def first_num():  
    import random  
    ran_list = [10, 193, 228, 2227, 5605, 1834]  
    for i in range(len(ran_list), 1, -1):  
        ran_list[i - 1] = sum(ran_list[:i])  

    a = random.randrange(0, 10097)  
    for i in range(len(ran_list)):  
        if a < ran_list[i]:  
            break  

    return i+1  
s=[first_num() for i in range(100000)]

print(len([ x for x in s if x ==5])/100000)  
result: 运行三次的值分别是：0.55668，0.55515，0.55464，均比较接近55.6%