python random

In [120]: import random

In [121]: l1 = (1, 2, 3)

In [122]: l2 = [1, 2, 3]

In [123]: ran
random  range   

In [123]: random.shuffle(l1)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-123-00db8a674af6> in <module>()
----> 1 random.shuffle(l1)

/usr/lib/python2.7/random.pyc in shuffle(self, x, random)
    287             # pick an element in x[:i+1] with which to exchange x[i]
    288             j = _int(random() * (i+1))
--> 289             x[i], x[j] = x[j], x[i]
    290 
    291     def sample(self, population, k):

TypeError: 'tuple' object does not support item assignment

In [124]: random.shuffle(l2)                                                                    

In [125]: l2
Out[125]: [3, 2, 1]

In [126]: a = l2

In [127]: a
Out[127]: [3, 2, 1]

In [128]: a = random.shuffle(l2)

In [129]: a

In [130]: a

In [131]: print a
None

上面的错误是因为元组内容不可更改

下面返回a的值是None是因为shuffle返回值的原因 ，shuffle只是在原基础上做的打乱

In [19]: import random

In [20]: random.random()
Out[20]: 0.9467622073347552

In [21]: random.uniform(1, 2)
Out[21]: 1.5264479206993298

In [22]: random.uniform(1, 1)
Out[22]: 1.0

In [23]: random.randint(1,3)
Out[23]: 1

In [24]: random.randrange(1, 100)
Out[24]: 7

In [25]: random.randrange(1, 100, 3)
Out[25]: 22

In [26]: random.randrange(1, 100, 3)
Out[26]: 28

In [27]: random.randrange(1, 100, 3)
Out[27]: 58

In [28]: random.randrange(1, 100, 3)
Out[28]: 91

In [29]: random.choice(range(10))
Out[29]: 5

In [30]: random.sample(range(10), 3)
Out[30]: [9, 6, 2]