python3基础-切片

2019独角兽企业重金招聘Python工程师标准>>>

切片简介

Python切片是list的一项基本的功能，可适用于str字符串、 list列表、 tuple元组

切片默认以下标索引方式进行，初始位为0，末尾为-1。区间为闭区间

==注意：切片方法在字符串、列表、元组中是通用的，以下仅为部分示例==

字符串切片示例

[0:3] 取字符串第一位到第三位

a = "123456789"
print(a[0:3])

123

或

[:3]

a = "123456789"
print(a[:3])

123

列表切片示例

[:-2] 去除列表后两个元素

li = ["小明","小王","小马","小赵","小李","小蒋"]
print(li[:-2])

['小明', '小王', '小马', '小赵']

[-2:] 取列表后两个元素

li = ["小明","小王","小马","小赵","小李","小蒋"]
print(li[-2:])

['小李', '小蒋']

元组切片示例

[::2] 取公差间隔元素

tu = (0,1,2,3,4,5,6,7,8,9,)
print(tu[::2])

(0, 2, 4, 6, 8)

[::-1] 反转切片

tu = (0,1,2,3,4,5,6,7,8,9,)
print(tu[::-1])

(9, 8, 7, 6, 5, 4, 3, 2, 1, 0)

[::-3] 反转公差间隔元素切片

tu = (0,1,2,3,4,5,6,7,8,9,)
print(tu[::-3])

tu = (0,1,2,3,4,5,6,7,8,9,)
print(tu[::-3])

转载于:https://my.oschina.net/zhaojunhui/blog/1631315