python random（不完整版）

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