Python随机数random模块使用指南

random 模块是Python自带的模块，除了生成最简单的随机数以外，还有很多功能。

random.random()

用来生成一个0~1之间的随机浮点数，范围[0,10

>>> import random
>>> random.random()
0.5038461831828231

random.uniform(a,b)

返回a,b之间的随机浮点数，范围[a,b]或[a,b),取决于四舍五入，a不一定要比b小。

>>> random.uniform(50,100)
76.81733455677832
>>> random.uniform(100,50)
52.98730193316595

random.randint(a,b)

返回a,b之间的整数，范围[a,b]，注意：传入参数必须是整数，a一定要比b小

>>> random.randint(50,100)
54
>>> random.randint(100,50)
 
Traceback (most recent call last):
 File "<pyshell#6>", line 1, in <module>
  random.randint(100,50)
 File "C:Python27librandom.py", line 242, in randint
  return self.randrange(a, b+1)
 File "C:Python27librandom.py", line 218, in randrange
  raise ValueError, "empty range for randrange() (%d,%d, %d)" % (istart, istop, width)
ValueError: empty range for randrange() (100,51, -49)
>>> random.randint(50.5,100.6)
 
Traceback (most recent call last):
 File "<pyshell#7>", line 1, in <module>
  random.randint(50.5,100.6)
 File "C:Python27librandom.py", line 242, in randint
  return self.randrange(a, b+1)
 File "C:Python27librandom.py", line 187, in randrange
  raise ValueError, "non-integer arg 1 for randrange()"
ValueError: non-integer arg 1 for randrange()

random.randrang([start], stop[, step])

返回有个区间内的整数，可以设置step。只能传入整数，random.randrange(10, 100, 2)，结果相当于从[10, 12, 14, 16, … 96, 98]序列中获取一个随机数。

>>> random.randrange(100)
58
>>> random.randrange(10,100,2)
54

random.choice(sequence)

从序列中随机获取一个元素，list, tuple, 字符串都属于sequence。这里的sequence 需要是有序类型。random.randrange(10,100,2)在结果上与 random.choice(range(10,100,2) 等效。

>>> random.choice(("stone","scissors","paper"))
'stone'
>>> random.choice(["stone","scissors","paper"])
'scissors'
>>> random.choice("Random")
'm'

random.shuffle(x[,random])

用于将列表中的元素打乱，俗称为洗牌。会修改原有序列。

>>> poker = ["A","2","3","4","5","6","7","8","9","10","J","Q","K"]
>>> random.shuffle(poker)
>>> poker
['4', '10', '8', '3', 'J', '6', '2', '7', '9', 'Q', '5', 'K', 'A']

random.sample(sequence,k)

从指定序列中随机获取k个元素作为一个片段返回，sample函数不会修改原有序列。

>>> poker = ["A","2","3","4","5","6","7","8","9","10","J","Q","K"]
>>> random.sample(poker,5)
['4', '3', '10', '2', 'Q']

上述几个方式是Python常用的一些方法，但是关于随机数还有很多的故事。下回分解~