列表的操作

增

• 列表赋值

names = ['a','b','c','d','e','f']
print(names)

#['a', 'b', 'c', 'd', 'e', 'f']

•  插入

names = ['a','b','c','d','e','f']
names.append('g')       #插到最后
names.insert(1,'a1')    #指定位置插入
print(names)

#['a', 'a1', 'b', 'c', 'd', 'e', 'f', 'g']

•  列表合并

 

names = ['a','b','c','d','e','f']
names2 = [1,2,3,4,5]
names.extend(names2)    #列表合并不会删除被合并列表
print(names,names2)

#['a', 'b', 'c', 'd', 'e', 'f', 1, 2, 3, 4, 5] [1, 2, 3, 4, 5]

查

•  切片

names = ['a','b','c','d','e','f']
print(names)
print(names[2])
print(names[3:5])      # 顾头不顾尾
print(names[:2])       # =[0:2],0可以省略
print(names[-4:-1])
print(names[-4:])
print(names[0:5:2])    #步长切片

'''
['a', 'b', 'c', 'd', 'e', 'f']
c
['d', 'e']
['a', 'b']
['c', 'd', 'e']
['c', 'd', 'e', 'f']
['a', 'c', 'e']
'''

• 索引

names = ['a','b','c','d','e','f']
print(names.index('d'))   #索引
print(names[names.index('d')])

'''
3
d
'''

• 统计

names = ['a','b','c','d','e','f','f','f','f']
print(names.count('f'))    #统计

#4

 

改

names = ['a','b','c','d','e','f']
names[3] = 'd9'
print(names)

#['a', 'b', 'c', 'd9', 'e', 'f']

 

删

• 删除

names = ['a','b','c','d','e','f']
names.remove('c')
del names[1]
names.pop()   #指定位置删除，不指定默认删除最后一个：names.pop(3) = del names[3]
print(names)

#['a', 'd', 'e']

 

• 删除变量

names = ['a','b','c','d','e','f']
del names
print(names)

#NameError: name 'names' is not defined

• 清空列表

names = ['a','b','c','d','e','f','f','f','f']
names.clear()               #清空列表
print(names)

#[]

 其他

•  浅copy

names = ['a','b','c','d','e',[0,1,2],'f']
names2 = names.copy()   #copy为浅copy，只copy第一层列表，第二层列表复制的是内存地址
                        #import copy，names2=copy.copy(name) 同样为浅copy
names[2] = 'CC'
names[5][1] = 155       #names2第二层列表会随之变化
print(names)
print(names2)

'''
['a', 'b', 'CC', 'd', 'e', [0, 155, 2], 'f']
['a', 'b', 'c', 'd', 'e', [0, 155, 2], 'f']
'''

• 深copy

import copy
names = ['a','b','c','d','e',[0,1,2],'f']
names2 = copy.deepcopy(names)   #深copy会导致占用双倍内存，慎用
names[2] = 'CC'
names[5][1] = 155
print(names)
print(names2)

'''
['a', 'b', 'CC', 'd', 'e', [0, 155, 2], 'f']
['a', 'b', 'c', 'd', 'e', [0, 1, 2], 'f']
'''

•  翻转

names = ['a','b','c','d','e','f','f','f','f','1','F','@','56']
names.reverse()  #翻转
print(names)

#['56', '@', 'F', '1', 'f', 'f', 'f', 'f', 'e', 'd', 'c', 'b', 'a']

• 排序

names = ['a','b','c','d','e','f','f','f','f','1','F','@','56']
names.sort()     #排序
print(names)

#['1', '56', '@', 'F', 'a', 'b', 'c', 'd', 'e', 'f', 'f', 'f', 'f']

•  循环

names = ['a','b','c','d','e',[0,1,2],'f']
for i in names:
    print(i)

'''
a
b
CC
d
e
[0, 155, 2]
f
'''