Python 2.7:如何使用列表

列表使用[ ]，列表包含的元素可以是多种不同的类型;
[cc lang=”python”]
In [1]: squares = [1, 4, 9, 16, 25]
In [2]: squares
Out[2]: [1, 4, 9, 16, 25]
[/cc]
跟字符串一样，列表也可以使用索引和切片：
[cc lang=”python”]
In [3]: squares[0]
Out[3]: 1
In [4]: squares[-1]
Out[4]: 25
In [5]: squares[-3:]
Out[5]: [9, 16, 25]
[/cc]
所有的切片操作都会返回一个新的包含切片内容的新列表，以下操作表示生成一个原列表的副本：
[cc lang=”python”]
In [6]: squares[:]
Out[6]: [1, 4, 9, 16, 25]
[/cc]
列表也支持连接符：
[cc lang=”python”]
In [7]: squares + [36, 49, 64, 81, 100]
Out[7]: [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
[/cc]
列表是可变的，与字符串不同：
[cc lang=”python”]
In [8]: cubes = [1, 8, 27, 65, 125]
In [9]: 4 ** 3
Out[9]: 64
In [10]: cubes[3] = 64
In [11]: cubes
Out[11]: [1, 8, 27, 64, 125]
[/cc]
使用append函数可以在列表的末尾添加新元素：
[cc lang=”python”]
In [12]: cubes.append(216)
In [13]: cubes.append(7 ** 3)
In [14]: cubes
Out[14]: [1, 8, 27, 64, 125, 216, 343]
[/cc]
给切片分配新的内容也可以：
[cc lang=”python”]
In [15]: letters = [‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’, ‘g’]
In [16]: letters
Out[16]: [‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’, ‘g’]
In [17]: letters[2:5] = [‘C’, ‘D’, ‘E’]
In [18]: letters
Out[18]: [‘a’, ‘b’, ‘C’, ‘D’, ‘E’, ‘f’, ‘g’]
In [19]: letters[2:5] = []
In [20]: letters
Out[20]: [‘a’, ‘b’, ‘f’, ‘g’]
In [21]: letters[:] = []
In [22]: letters
Out[22]: []
[/cc]
使用内置函数len也可以计算列表的长度：
[cc lang=”python”]
In [23]: letters = [‘a’, ‘b’, ‘c’, ‘d’]
In [24]: len(letters)
Out[24]: 4
[/cc]
也可以在列表中放进列表：
[cc lang=”python”]
In [25]: a = [‘a’, ‘b’, ‘c’]
In [26]: n = [1, 2, 3]
In [27]: x = [a, n]
In [28]: x
Out[28]: [[‘a’, ‘b’, ‘c’], [1, 2, 3]]
In [29]: x[0]
Out[29]: [‘a’, ‘b’, ‘c’]
In [30]: x[0][1]
Out[30]: ‘b’
[/cc]
来源：http://linjohn.blog.51cto.com/1026193/1608870