python切片处理

python切片处理

创建切片，可指定要使用的第一个元素的索引和最后一个元素的索引加一

#创建列表players
players = ['charles', 'martina', 'michael', 'florence', 'eli']
#打印出列表
print(players)
=>
['charles', 'martina', 'michael', 'florence', 'eli']#切片1
print(players[1:4])#打印从索引1位置的元素开始的三个元素
=>['martina', 'michael', 'florence']
#切片2
print(players[:4])#如果没有指定第一个索引，python将自动从列表的开头开始
=>['charles', 'martina', 'michael', 'florence']
#切片3
print(players[2:])#从索引为2，打印最后三个
=>['michael', 'florence', 'eli']
#切片4
print(players[-3:])#打印倒数三个元素
['michael', 'florence', 'eli']

遍历切片

for player in players[:]:print(player.title())
=>
Charles
Martina
Michael
Florence
Eli

复制列表

得到两个列表
相当于复制一个副本

copy = players[:]
players.append('ev')
copy.append('wuh')
print(players)
print(copy)
=>
['charles', 'martina', 'michael', 'florence', 'eli', 'ev']
['charles', 'martina', 'michael', 'florence', 'eli', 'wuh']

一个列表
相当于赋值

copy1 = players
players.append('ev')
copy1.append('wuh')
print(players)
print(copy1)
=>
['charles', 'martina', 'michael', 'florence', 'eli', 'wuh']
['charles', 'martina', 'michael', 'florence', 'eli', 'wuh']