python中的切片

In [1]:  L = [‘Michael‘, ‘Sarah‘, ‘Tracy‘, ‘Bob‘, ‘Jack‘]

In [2]: L
Out[2]: [‘Michael‘, ‘Sarah‘, ‘Tracy‘, ‘Bob‘, ‘Jack‘]

In [3]: L[0:3]
Out[3]: [‘Michael‘, ‘Sarah‘, ‘Tracy‘]
取出下标从0到2的数据

In [4]: L[::2]
Out[4]: [‘Michael‘, ‘Tracy‘, ‘Jack‘]
以2为间隔取出数据

In [5]: L[:2]
Out[5]: [‘Michael‘, ‘Sarah‘]
取出下标从0到1的数据，例中0省略不写

In [6]: L[:-1]
Out[6]: [‘Michael‘, ‘Sarah‘, ‘Tracy‘, ‘Bob‘]
负数表示倒数

In [7]: L[-1:-3]
Out[7]: []
这样取不出数据，切片从左到右进行

In [8]: L[-3:-1]
Out[8]: [‘Tracy‘, ‘Bob‘]


In [9]: L[-3:]
Out[9]: [‘Tracy‘, ‘Bob‘, ‘Jack‘]
倒数第3个到结束

In [10]: L[:]
Out[10]: [‘Michael‘, ‘Sarah‘, ‘Tracy‘, ‘Bob‘, ‘Jack‘]
所有