25 -3 random模块

 随机的概念：

在某个范围内取到每一个值的概率是相同的


1、随机小数

print(random.random())          # 0-1之内的随机小数
print(random.uniform(1,5))     # 任意范围之内的随机小数

2、随机整数  （重要）

print(random.randint(1,2)) # [1,2] 包含2在内的范围内随机取整数

print(random.randrange(1,2)) # [1,2)不包含2在内的范围内随机取整数

print(random.randrange(1,10,2)) # [1,10)不包含10在内的范围内随机取奇数

3、随机抽取          -----choice、sample

  　　　　1）随机抽取一个值 choice(列表)

lst = [1,2,3,'aaa',('zxd','cyy')]
ret = random.choice(lst)
print(ret)  # 从列表中抽取一个值取出来

　　　　2）随机抽取多个值  sample(列表,个数)

lst = [1,2,3,'aaa',('zxd','cyy')]

ret = random.sample(lst,2)
print(ret)   #取出两个值

4、打乱顺序    ---shuffle(列表)

　　　　对原列表操作

lst = [1,2,3,'aaa',('zxd','qqxing')]
random.shuffle(lst)
print(lst)

小试牛刀：

  需求：生成4位数字的随机验证码

code = ''
for i in range(4):
    num = random.randint(0,9)
    code += str(num)
print(code)

def rand_code(n=4):
    code = ''
    for i in range(n):
        num = random.randint(0, 9)
        code += str(num)
    return code


print(rand_code())
print(rand_code(6))


# 巧妙之处在于默认是4为验证码，也可以人为修改位数，例如上面扩充到6位

扩充知识点:

　　a的ascill码  为97

　　z   为122

print(chr(97))   #a
print(chr(122))  #z

print(chr(65))   # A
print(chr(90))　　# Z

需求升级：数字+字母  6位

code = ''
for i in range(6):
    rand_num = str(random.randint(0,9))
    rand_alph = chr(random.randint(97,122))
    rand_alph_upper = chr(random.randint(65,90))
    atom_code = random.choice([rand_num,rand_alph,rand_alph_upper])
    code += atom_code
print(code)

import random

def rand_code(n=6):
    code = ''
    for i in range(n):
        rand_num = str(random.randint(0,9))
        rand_alph = chr(random.randint(97,122))
        rand_alph_upper = chr(random.randint(65,90))
        atom_code = random.choice([rand_num,rand_alph,rand_alph_upper])
        code += atom_code
    return code

ret = rand_code()
print(ret)

嘿！ 再次升级: 我可以设置全数字或者数字+字母形式的验证码

def rand_code(n=6, alph_flag=True):
    code = ''
    for i in range(n):
        rand_num = str(random.randint(0, 9))
        if alph_flag:
            rand_alph = chr(random.randint(97, 122))
            rand_alph_upper = chr(random.randint(65, 90))
            rand_num = random.choice([rand_num, rand_alph, rand_alph_upper])
        code += rand_num
    return code


ret = rand_code(n=4)
print(ret)