#!/usr/bin/env python 
# -*- coding: utf-8 -*- 
#python2.7x 
#random_weight.py 
#author: orangleliu@gmail.com 2014-10-11 
 
''''' 
每个元素都有权重，然后根据权重随机取值 
 
输入 {"A":2, "B":2, "C":4, "D":10, "E": 20} 
输出一个值 
''' 
import random 
import collections as coll 
 
data = {"A":2, "B":2, "C":4, "D":6, "E": 11} 
 
#第一种 根据元素权重值 "A"*2 ..等，把每个元素取权重个元素放到一个数组中，然后最数组下标取随机数得到权重 
def list_method(): 
 all_data = [] 
 for v, w in data.items(): 
  temp = [] 
  for i in range(w): 
   temp.append(v) 
  all_data.extend(temp) 
   
 n = random.randint(0,len(all_data)-1) 
 return all_data[n] 
  
#第二种 也是要计算出权重总和，取出一个随机数，遍历所有元素，把权重相加sum，当sum大于等于随机数字的时候停止，取出当前的元组 
def iter_method(): 
 total = sum(data.values()) 
 rad = random.randint(1,total) 
  
 cur_total = 0 
 res = "" 
 for k, v in data.items(): 
  cur_total += v 
  if rad<= cur_total: 
   res = k 
   break 
 return res 
  
  
def test(method): 
 dict_num = coll.defaultdict(int) 
 for i in range(100): 
  dict_num[eval(method)] += 1 
 for i,j in dict_num.items(): 
  print i, j  
  
if __name__ == "__main__": 
 test("list_method()") 
 print "-"*50 
 test("iter_method()") 

A 4 
C 14 
B 7 
E 44 
D 31 
-------------------------------------------------- 
A 8 
C 16 
B 6 
E 43 
D 27