Python3.5--列表（上）

列表是Python里面最常用的数据类型之一，通过列表可以对数据实现最方便的存储、修改等操作。

1、列表的定义

names = ["Liu","Zhang","Mao"]print(names)#打印结果#['Liu', 'Zhang', 'Mao']

2、通过下标取列表中的元素，其中，下标是从0开始计数的

names = ["Liu","Zhang","Mao"]print(names[0],names[2])print(names[-1],names[-2])   #倒着取#打印结果#['Liu', 'Zhang', 'Mao']#Liu Mao#Mao Zhang

3、从列表中取多个元素：切片（顺序：从左向右）

names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names[1:4])#打印结果#['Zhang', 'Mao', 'Sun']#特点：顾头不顾尾（左闭右开）names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names[-3:])   #如果想取最后一个，必须不能写-1，只能这么写#结果：['Sun', 'Wang', 'Song']  print(names[:3])#如果是从头开始取，0可以忽略#结果：['Liu', 'Zhang', 'Mao']

4、在列表后边追加新的字符串：调用.append("新添加的内容")

names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names)names.append("Zhao")print(names)#结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song']#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Zhao']

5、在列表中插入新的字符串：调用.insert(要插入的位置下标,要插入的内容)

names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names)names.insert(1,"Chen")print(names)#结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song']#['Liu', 'Chen', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song']

6、在列表中修改某个位置的字符串：直接修改该位置的内容

names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names)names[2] = "Li"print(names)#运行结果#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song']#['Liu', 'Zhang', 'Li', 'Sun', 'Wang', 'Song']

7、在列表中删除某个字符串：直接删除del；删除指定的字符串：remove；删除最后一个元素（不添加下标时，添加下标与del等价）：pop

names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names)del names[1]print(names)names.remove("Mao")print(names)names.pop()print(names)#输出结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song']#['Liu', 'Mao', 'Sun', 'Wang', 'Song']#['Liu', 'Sun', 'Wang', 'Song']#['Liu', 'Sun', 'Wang']

8、

在列表中查找某个元素所在的位置：调用.index("要查找的元素名")

names = ["Liu","Zhang","Mao","Sun","Wang","Song"]print(names.index("Mao"))print(names[names.index("Mao")])#运行结果：#2#Mao

9、在列表中统计同一个元素出现的次数：调用.count("要统计的元素名")

names = ["Liu","Zhang","Mao","Sun","Wang","Song","Mao","Mao"]print(names.count("Mao"))#运行结果#3

10、清空列表中元素：调用.clear()

names = ["Liu","Zhang","Mao","Sun","Wang","Song","Mao","Mao"]names.clear()print(names)#运行结果：#[]

11、翻转列表中的元素的位置：调用.reverse()

names = ["Liu","Zhang","Mao","Sun","Wang","Song","Mao","Mao"]print(names)names.reverse()print(names)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']#['Mao', 'Mao', 'Song', 'Wang', 'Sun', 'Mao', 'Zhang', 'Liu']

12、排序列表中的元素（安装字母的起始顺序）：调用.sort()

names = ["Liu","Zhang","Mao","Sun","Wang","Song","Mao","Mao"]print(names)names.sort()print(names)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Mao', 'Mao', 'Mao', 'Song', 'Sun', 'Wang', 'Zhang']

13、在列表中扩展某些新元素：调用.extend(扩展的内容)

names = ["Liu","Zhang","Mao","Sun","Wang","Song","Mao","Mao"]print(names)names2 = ["1san","Shi","Meng"]names.extend(names2)print(names)print(names2)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao', '1san', 'Shi', 'Meng']#['1san', 'Shi', 'Meng']  

14、复制列表中的元素：调用.copy()。复制结束后再修改原来列表里面的元素，拷贝的内容不变。

names = ["Liu","Zhang","Mao","Sun","Wang","Song","Mao","Mao"]names1 = names.copy()print(names)print(names1)names[0] = "刘"print(names)print(names1)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']#['刘', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', 'Wang', 'Song', 'Mao', 'Mao']

15、列表里面还可以嵌套新的列表（被嵌套的整体作为嵌套的一个下标）

names = ["Liu","Zhang","Mao","Sun",["Li","Tian"],"Wang","Song","Mao","Mao"]print(names)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', ['Li', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']

（1）注：copy结合嵌套列表：copy只是复制第一层的元素，嵌套的第二层只是复制内存地址，不复制元素内容（浅复制）

names = ["Liu","Zhang","Mao","Sun",["Li","Tian"],"Wang","Song","Mao","Mao"]names1 = names.copy()print(names)print(names1)names[0] = "刘"names[4][0] = "李"print(names)print(names1)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', ['Li', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', ['Li', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']#['刘', 'Zhang', 'Mao', 'Sun', ['李', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', ['李', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']

（2）引入独立的copy模块，调用copy模块下面的copy方法实现复制（与上面的浅复制是一样的打印效果）

import copynames = ["Liu","Zhang","Mao","Sun",["Li","Tian"],"Wang","Song","Mao","Mao"]names1 = copy.copy(names)print(names)print(names1)names[0] = "刘"names1[4][0] = "李"print(names)

（3）要想完全独立复制，需调用copy模块下面的deepcopy方法，一般情况下不需要完全独立复制一个列表（少用deepcopy）。

import copynames = ["Liu","Zhang","Mao","Sun",["Li","Tian"],"Wang","Song","Mao","Mao"]names1 = copy.deepcopy(names)print(names)print(names1)names[0] = "刘"names[4][0] = "李"print(names)print(names1)#运行结果：#['Liu', 'Zhang', 'Mao', 'Sun', ['Li', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', ['Li', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']#['刘', 'Zhang', 'Mao', 'Sun', ['李', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']#['Liu', 'Zhang', 'Mao', 'Sun', ['Li', 'Tian'], 'Wang', 'Song', 'Mao', 'Mao']

16、列表循环（for循环）

names = ["Liu","Zhang","Mao","Sun",["Li","Tian"],"Wang","Song"]for i in names:    print(i)#运行结果：#Liu#Zhang#Mao#Sun#['Li', 'Tian']#Wang#Song

17、列表的切片（以步长是2为例）

names = ["Liu","Zhang","Mao","Sun",["Li","Tian"],"Wang","Song"]print(names[0:-1:2])   #0和-1都可以去掉，即：print(names[::2])#运行结果：#['Liu', 'Mao', ['Li', 'Tian']]