python列表的切片

python列表的切片 列表切片[开始索引:结束索引]

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
print(players[0:3])  # => ['charles', 'martina', 'michael'] 

可以生成列表的任何子集，如你要提取列表的第2~4个元素，可将起始索引指定为1，将结束索引指定为4：

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
print(players[1:4]) #=>['martina', 'michael', 'florence'] 

如果没有指定第一个索引，Python将自动从列表开头开始：

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
print(players[:4]) #=>['charles', 'martina', 'michael', 'florence']  

要让切片结束于列表末尾，也可使用类似的语法,返回从第3个元素到列表末尾的所有元素：

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
print(players[2:]) #=>['michael', 'florence', 'eli'] 

负数索引返回离列表末尾相应距离的元素，例如，如果你要输出名单上的最后三名队员，可使用切片players[-3:]：

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
print(players[-3:]) #=>['michael', 'florence', 'eli'] 

复制列表

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
player2 = players[:]
print(player2.append('11'))
print(players)  # = >['charles', 'martina', 'michael', 'florence', 'eli'] 
print(player2)  # = >['charles', 'martina', 'michael', 'florence', 'eli', '11']