标签：eve 表复制 style 简单 影响 pytho NPU 一个 默认
浅拷贝：简单类型元素全复制，引用类型元素只复制引用
L1 = [3,2,1,[4,5,6],8,‘abc‘] L1 [3, 2, 1, [4, 5, 6], 8, ‘abc‘] L2 = L1.copy() L2 [3, 2, 1, [4, 5, 6], 8, ‘abc‘]
L1[3][1] = 10 #修改L1中的元素L2也随之变化 L1 [3, 2, 1, [4, 10, 6], 8, ‘abc‘] L2 [3, 2, 1, [4, 10, 6], 8, ‘abc‘]
深拷贝：copy模块提供了deepcopy，引用类型完全复制为新元素
import copy L3 = copy.deepcopy(L1) L3 [3, 2, 1, [4, 10, 6], 8, ‘abc‘]
L1[3][1] = 20 L1 [3, 2, 1, [4, 20, 6], 8, ‘abc‘] L3 #L3为深拷贝新生成的列表，修改L1元素对L3无影响 [3, 2, 1, [4, 10, 6], 8, ‘abc‘]
*：对引用类型做浅拷贝处理
L4 = [[1,2,3]] * 3 L4 [[1, 2, 3], [1, 2, 3], [1, 2, 3]] L4[1][1] = 10 L4 [[1, 10, 3], [1, 10, 3], [1, 10, 3]]
for x in L4: print(x) print(id(x)) #取内存地址 [1, 10, 3] 84289032 [1, 10, 3] 84289032 [1, 10, 3] 84289032 #内存地址相同
L5 = [[1, 2, 3], [1, 2, 3], [1, 2, 3]] L5 [[1, 2, 3], [1, 2, 3], [1, 2, 3]] for x in L5: print(x) print(id(x)) [1, 2, 3] 87157000 [1, 2, 3] 84213512 [1, 2, 3] 87157128
remove(value) 基于元素查找，移除第一个出现的元素，并会引起列表元素移动O(n)
L6 = [3,2,1,4,5,6,7,2,3,4] L6 [3, 2, 1, 4, 5, 6, 7, 2, 3, 4] L6.remove(2) L6 [3, 1, 4, 5, 6, 7, 2, 3, 4] L6.remove(10) --------------------------------------------------------------------------- ValueError Traceback (most recent call last) <ipython-input-31-8cf95df45268> in <module> ----> 1 L6.remove(10) ValueError: list.remove(x): x not in list
pop(index) 基于索引查找，移除索引位元素O(1)，并会引起列表元素移动O(n)
L6.pop(3)
5 L6 [3, 1, 4, 6, 7, 2, 3, 4] L6.pop(10) L6 --------------------------------------------------------------------------- IndexError Traceback (most recent call last) <ipython-input-33-8663c8410c3d> in <module> ----> 1 L6.pop(10) 2 L6 IndexError: pop index out of range
pop() 移除列表尾部一个元素O(1)，效率高
L6.pop()
4
L6
[3, 1, 4, 6, 7, 2, 3]
clear() 清除列表所有元素，使列表长度为0，元素引用计数减1，剩下一个空列表
L6.clear()
L6
[]
reverse() 将列表元素反转，修改自身
L7 = [3,2,1,4,5,6,7,2,3,4] L7 [3, 2, 1, 4, 5, 6, 7, 2, 3, 4] L7.reverse() L7 [4, 3, 2, 7, 6, 5, 4, 1, 2, 3]
sort(key=function,reverse=True) 对列表元素排序，默认升序，修改自身
key指定不同类型元素如何排序，只在排序中使用，不修改元素
reverse=True为降序排序
L8 = [3,2,1,4,5,6,7,2,3,4,‘a‘,‘b‘,‘c‘] L8 [3, 2, 1, 4, 5, 6, 7, 2, 3, 4, ‘a‘, ‘b‘, ‘c‘] L8.sort() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) <ipython-input-46-951f259be954> in <module> ----> 1 L8.sort() TypeError: ‘<‘ not supported between instances of ‘str‘ and ‘int‘ L8.sort(key=str,reverse=True) L8 [‘c‘, ‘b‘, ‘a‘, 7, 6, 5, 4, 4, 3, 3, 2, 2, 1]
in 判断元素在列表中是否存在，返回bool值
‘c‘ in L8 True 4 in L8 True 10 in L8 False
Python列表操作与深浅拷贝（7）——列表深浅拷贝、删除、反转、排序
标签：eve 表复制 style 简单 影响 pytho NPU 一个 默认
原文地址：https://www.cnblogs.com/omgasw/p/11613085.html
