python list输出每隔五个换行 python列表每五个输出

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 copy
names = ["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 copy
names = ["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']]