【Python之旅】第二篇（二）：列表与元组

说明：

Python中的列表类似于其它高级语言中的数组，不过Python的列表操作起来要轻松很多。
Python中列表的学习主线主要是围绕对列表参数的操作使用上，重点关注的应该有如下这些：

names.append(
names.count(
names.extend(
names.index(
names.insert(
names.pop(
names.remove(
names.reverse(
names.sort(

下面的内容基本上都是围绕上面的操作进行说明。

1.基本操作

·基本的操作主要有如下：

names[num]：排序为数字num的元素
names[-1:]：最后1个元素
names[-5:]：最后5个元素
names[-5:-1]：最后5个元素，但不包括最后1个元素（即不包括names[-1]）
names[:5]：开始5个元素（即不包括names[5]）
names[0:5]：开始5个元素（即不包括names[5]）
names[10:15]：names[10]到names[14]

·上面有取范围的情况，前后两个数字，可以记为：“虎头蛇尾”，即取前不取后

· 以下面的环境做一个简单的测试：

>>> names = ['xpleaf','yonghaoyip','CL']
>>> names.extend(range(30))
>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]

(1）names[num]：排序为数字num的元素

>>> names[2]
'CL'

（2）names[-1：]：最后1个元素

>>> names[-1:]
[29]

（3）names[-5:]：最后5个元素

>>> names[-5:]
[25, 26, 27, 28, 29]

（4）names[-5:-1]：最后5个元素，但不包括最后1个元素（即不包括names[-1]）

>>> names[-5:-1]
[25, 26, 27, 28]

（5）names[:5]或names[0:5]：开始5个元素（即不包括names[5]）

>>> names[:5]
['xpleaf', 'yonghaoyip', 'CL', 0, 1]
>>> names[0:5]
['xpleaf', 'yonghaoyip', 'CL', 0, 1]

（6）names[10:15]：names[10]到names[14]

>>> names[10:15]
[7, 8, 9, 10, 11]
>>> names[10]
7
>>> names[14]
11
>>> names[15]
12

2.append()参数

·基本功能：向列表中添加元素
·基本语法：

names.append('xpleaf')

·append()参数在列表的最后面增加元素，一次只能添加一个；
·演示如下：

>>> names.append('xpleaf')
>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf']

3.count()参数

·基本功能：计算列表中相同元素的个数·基本语法：

names.count('xpleaf')

·演示如下：

>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf']
>>> names.count('xpleaf')
2

·进阶演示：count()可以比较字符串中是否含有包含的字符串

>>> name = 'xpleaf'
>>> name.count('xp')
1
>>> name.count('leaf')
1
>>> name.count('xpleaf123')
0
===>如果包含有查找的字符串，则返回1，否则返回0

4.extend()参数

·基本功能：将另一个列表中的元素合并到当前列表中·基本语法：

names.extend(range(10))
等价于下面的内容：
names = names + range(10)  ===>列表也可以直接做加法，Python中序列的特性

·演示如下：

>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf']
>>> range(10)    ===>range()的输出本来就是一个列表
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> names.extend(range(10))
>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

·append()添加的是列表中的元素，如果写成下面这样：

names.append(range(10))
===>只会在names列表末尾处添加一个列表元素[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

5.index()参数
·基本功能：找出需要查找的列表元素的索引号·基本语法：

names.index('xpleaf')

·如果列表中有多个相同元素，index()找出的只是第1个相同元素的索引号·演示如下：

>>> names.append('CL')
>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'CL']
>>> names.index('xpleaf')
0
>>> names.index('CL')
2
>>> names[2]
'CL'

6.inset()参数

·基本功能：在列表中某一位置插入元素·基本语法：

names.insert(6,'love') ===>在列表的索引号为6的位置中插入元素'love'

·演示如下：

>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'CL']
>>> names.insert(6,'love')
>>> names
['xpleaf', 'yonghaoyip', 'CL', 0, 1, 2, 'love', 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'CL']
>>> names[6]
'love'

--小的综合操作：将上面列表中的'xpleaf'替换为'xpleaf_Yip'
·未充分利用Python特性的笨方法：

>>> while True:
...   if names.count('xpleaf') == 0:
...     break
...   else:
...     names[names.index('xpleaf')] = 'xpleaf_Yip'
...
>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 0, 1, 2, 'love', 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'CL']

·虽然可以达到目的，但实际上该方法是比较笨的；

·充分利用Python特性的方法：

>>> for i in range(names.count('xpleaf')):
...   names[names.index('xpleaf')] = 'xpleaf_Yip'
...
>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 0, 1, 2, 'love', 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'CL']

7.pop()参数
·基本功能：将列表中最后一个元素删除·基本语法：

names.pop()

·演示如下：

>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 0, 1, 2, 'love', 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'CL']
>>> names.pop()
'CL'
>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 0, 1, 2, 'love', 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

8.remove()参数
·基本功能：删除列表中指定内容的元素·基本语法：

names.remove('love')    ===>删除列表中'love'元素

·演示如下：

>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 0, 1, 2, 'love', 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> names.remove('love')
>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

·如果存在多个相同的元素，则只删除第1个：

>>> names.remove(0)
>>> names
['xpleaf_Yip', 'yonghaoyip', 'CL', 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'xpleaf_Yip', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

9.sort()参数
·基本功能：以ASCII表的顺序对列表中的元素进行排序，纯数值元素会在前面·基本语法：

names.sort()

·演示如下：

>>> names.sort()
>>> names
[0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 'CL', 'xpleaf_Yip', 'xpleaf_Yip', 'yonghaoyip']

·如果有多个元素的字符串，则按字符串中的字符依次顺序比较，直到有不相同的为止；

10.reverse()参数
·基本功能：将原来列表中的元素倒序存储·基本语法：

names.reverse()

·演示如下：

>>> names.reverse()
>>> names
['yonghaoyip', 'xpleaf_Yip', 'xpleaf_Yip', 'CL', 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 9, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0]

11.与列表相关的其它操作
--删除列表中的元素：del
·不用remove()的方式删除，需要指定索引号；·演示如下：

>>> names
['yonghaoyip', 'xpleaf_Yip', 'xpleaf_Yip', 'CL', 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 9, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0]
>>> names[2]
'xpleaf_Yip'
>>> del names[2]
>>> names
['yonghaoyip', 'xpleaf_Yip', 'CL', 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 9, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0]

--将字符串内容变为列表中的元素：list()·演示如下：

>>> import string
>>> string.ascii_lowercase
'abcdefghijklmnopqrstuvwxyz'
>>> a = list(string.ascii_lowercase)
>>> a
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

--将列表中的元素连接为字符串：''.join()·str()只会将整个列表作为一个字符串：

>>> str(a)
"['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']"

·把列表元素连接成字符串方法如下：

>>> ''.join(a)
'abcdefghijklmnopqrstuvwxyz'
>>> '_'.join(a)
'a_b_c_d_e_f_g_h_i_j_k_l_m_n_o_p_q_r_s_t_u_v_w_x_y_z'

·''.join()参数中的列表元素只能是字符串型，不能是数值型：

>>> str(names)
"['yonghaoyip', 'xpleaf_Yip', 'CL', 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 9, 8, 8, 7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0]"
>>> ''.join(names)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: sequence item 3: expected string, int found

12.元组的提及
·元组跟列表一样，但元组内容一旦生成，无法修改；·元组主要是用来存储别人不能修改的内容；·元组的相关操作演示和说明如下：

>>> tuple = ('a', 'b', 'c', 1, 2, 3)
>>> tuple
('a', 'b', 'c', 1, 2, 3)
>>> tuple[3]    ===>取特定一个元素时，与列表类似
1
>>> tuple[3] = 'b'    ===>不能修改元组的元素内容
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> del tuple[3]    ===>也不能删除元组中的某一元素
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'tuple' object doesn't support item deletion
>>> list(tuple)
['a', 'b', 'c', 1, 2, 3]
>>> tuple.    ===>按tab键后可以看到只有count()和index（）参数与列表相似
……
tuple.count(
tuple.index(

·将元组变为列表时可使用list()函数。