python 獲取帶權重的隨機數

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import random
def random_weight(weight_data):
    total = sum(weight_data.values()) # 權重求和
    ra = random.uniform(0, total)# 在0與權重和之前獲取一個隨機數
    curr_sum = 0
    ret = None
    keys = weight_data.iterkeys() # 使用Python2.x中的iterkeys
#   keys = weight_data.keys()    # 使用Python3.x中的keys
    for k in keys:
        curr_sum += weight_data[k]# 在遍歷中，累加當前權重值
        if ra <= curr_sum:   #當隨機數<=當前權重和時，返回權重key
            ret = k
            break
    return ret
weight_data = {'a': 10, 'b': 15, 'c': 50,'d':12,'e':60,'f':30}
# res = random_weight(weight_data)
ww = set()
dic ={}
for i in xrange(100):
    res = random_weight(weight_data)
    if res not in ww:
        ww.add(res)
        dic[res] = 1
    else:
        dic[res]+=1
print(dic)