Python-列表操作

插入

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen"]

#将chenyunfei插入到gunyun前面

names.insert(1, "chenyunfei")#"1"是想插入的位置

print(names)

 

 

删除

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen"]

#第一种方法

names.remove("gunyun")

 

#第二种方法

del names[1]

 

返回列中元素的位置

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen"]

print(names.index("gunyun"))

 

统计列表中相同元素的个数

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen"]

names.append("gunyun")

 

print(names.count("gunyun"))

 

copy操作：浅拷贝（第二个列表中的每一个元素只是第一个列表中每个元素的一个引用），只拷贝了第一层列表

浅拷贝的三种方式：

person = ['name', ['saving', 100]]

 

p1 = copy.copy(person)

p2 = person[:]

p3 = list(person)

 

 

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen"]

name2 = names.copy()

print(names)

print(name2)

names[0] = "张扬"

print(names)

print(name2)

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen",["chen", "yun"]]

name2 = names.copy()

print(names)

print(name2)

#这次打印的话，name2中子列表中的值也发生了对应的话，这是因为在copy的时候，第一层拷贝的是值，对于子列表，可以认为拷贝的是指针，那么在打印的时候，当打印到name2的子列表时，就会去访问这个指针所指向的内存中存储的内容，所以就发生了变化

names[4][0] = 'CHEN'

print(names)

print(name2)

 

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen']

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen']

['张扬', 'gunyun', 'xiangpeng', 'xuliangchen']

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen']

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['chen', 'yun']]

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['chen', 'yun']]

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['CHEN', 'yun']]

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['CHEN', 'yun']]

 

浅拷贝在其中一个地方很有用：

import copy

 

#person当做模板

person = ['name', ['saving', 100]]

 

#用person模板生成p1和p2,假设p1和p2具有夫妻关系，他们具有一个相同的银行账号

p1 = person[:]

p2 = person[:]

 

p1[0] = 'alex'

p2[0] = 'fengjie'

 

print(p1)

print(p2)

 

p1[1][1] = 50

print(p2)

 

result:

['alex', ['saving', 100]]

['fengjie', ['saving', 100]]

['fengjie', ['saving', 50]]

 

 

 

深拷贝

import copy

 

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen"]

name2 = copy.deepcopy(names)

print(names)

print(name2)

names[0] = "张扬"

print(names)

print(name2)

names = ["zhangyang", "gunyun", "xiangpeng", "xuliangchen",["chen", "yun"]]

name2 = copy.deepcopy(names)

print(names)

print(name2)

names[4][0] = 'CHEN'

print(names)

print(name2)

 

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen']

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen']

['张扬', 'gunyun', 'xiangpeng', 'xuliangchen']

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen']

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['chen', 'yun']]

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['chen', 'yun']]

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['CHEN', 'yun']]

['zhangyang', 'gunyun', 'xiangpeng', 'xuliangchen', ['chen', 'yun']]