> random()               # 随机浮点数: 0.0 <= x < 1.0
0.37444887175646646

> uniform(2.5, 10.0)          # 随机浮点数: 2.5 <= x < 10.0
3.1800146073117523

> randrange(10)            # 0-9的整数：
7

> randrange(0, 101, 2)         # 0-100的偶数
26

> choice(['win', 'lose', 'draw'])   # 从序列随机选择一个元素
'draw'

> deck = 'ace two three four'.split()
> shuffle(deck)            # 对序列进行洗牌，改变原序列
> deck
['four', 'two', 'ace', 'three']

> sample([10, 20, 30, 40, 50], k=4)  # 不改变原序列的抽取指定数目样本，并生成新序列
[40, 10, 50, 30]

> # 6次旋转红黑绿轮盘(带权重可重复的取样)，不破坏原序列
> choices(['red', 'black', 'green'], [18, 18, 2], k=6)
['red', 'green', 'black', 'black', 'red', 'black']

> # 德州扑克计算概率Deal 20 cards without replacement from a deck of 52 playing cards
> # and determine the proportion of cards with a ten-value
> # (a ten, jack, queen, or king).
> deck = collections.Counter(tens=16, low_cards=36)
> seen = sample(list(deck.elements()), k=20)
> seen.count('tens') / 20
0.15

> # 模拟概率Estimate the probability of getting 5 or more heads from 7 spins
> # of a biased coin that settles on heads 60% of the time.
> trial = lambda: choices('HT', cum_weights=(0.60, 1.00), k=7).count('H') >= 5
> sum(trial() for i in range(10000)) / 10000
0.4169

> # Probability of the median of 5 samples being in middle two quartiles
> trial = lambda : 2500 <= sorted(choices(range(10000), k=5))[2] < 7500
> sum(trial() for i in range(10000)) / 10000
0.7958

import random
 
checkcode = ''
for i in range(4):
  current = random.randrange(0,4)
  if current != i:
    temp = chr(random.randint(65,90))
  else:
    temp = random.randint(0,9)
  checkcode += str(temp)
print(checkcode)

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import random, string

def gen_random_string(length):
  # 数字的个数随机产生
  num_of_numeric = random.randint(1,length-1)
  # 剩下的都是字母
  num_of_letter = length - num_of_numeric
  # 随机生成数字
  numerics = [random.choice(string.digits) for i in range(num_of_numeric)]
  # 随机生成字母
  letters = [random.choice(string.ascii_letters) for i in range(num_of_letter)]
  # 结合两者
  all_chars = numerics + letters
  # 洗牌
  random.shuffle(all_chars)
  # 生成最终字符串
  result = ''.join([i for i in all_chars])
  return result

if __name__ == '__main__':
  print(gen_random_string(64))