Python字典复制（）

Python Dictionary copy() 方法返回字典的浅表副本。

Python字典 copy()语法：

dict.copy()

Python字典 copy()参数：

The copy() method doesn’t take any parameters.

Python字典 copy()返回：

This method doesn’t modify the original, dictionary just returns copy of the dictionary.

Python字典 copy() 示例：

Input : original = {1:'geeks', 2:'for'}
        new = original.copy()
Output : original:  {1: 'one', 2: 'two'}
         new:  {1: 'one', 2: 'two'}

Python字典复制（）错误：

As we are not passing any parameters 
there is no chance of any error.

示例 1：使用Python字典 copy()

Python3

# Python program to demonstrate working
# of dictionary copy
original = {1: 'geeks', 2: 'for'}
 
# copying using copy() function
new = original.copy()
 
# removing all elements from the list
# Only new list becomes empty as copy()
# does shallow copy.
new.clear()
 
print('new: ', new)
print('original: ', original)

输出：

new:  {}
original:  {1: 'geeks', 2: 'for'}

示例 2： Python字典 copy() 和更新

Python3

# given dictionary
dict1 = {10: 'a', 20: [1, 2, 3], 30: 'c'}
print("Given Dictionary:", dict1)
 
# new dictionary and
# copying using copy() method
dict2 = dict1.copy()
print("New copy:", dict2)
 
# Updating dict2 elements and
# checking the change in dict1
dict2[10] = 10
dict2[20][2] = '45'  # list item updated
 
print("Updated copy:", dict2)

输出：

Given Dictionary: {10: 'a', 20: [1, 2, 3], 30: 'c'}
New copy: {10: 'a', 20: [1, 2, 3], 30: 'c'}
Updated copy: {10: 10, 20: [1, 2, '45'], 30: 'c'}

它与简单的赋值“=”有什么不同？

与 copy() 不同，赋值运算符执行深度复制。

Python3

# Python program to demonstrate difference
# between = and copy()
original = {1: 'geeks', 2: 'for'}
 
# copying using copy() function
new = original.copy()
 
# removing all elements from new list
# and printing both
new.clear()
print('new: ', new)
print('original: ', original)
 
original = {1: 'one', 2: 'two'}
 
# copying using =
new = original
 
# removing all elements from new list
# and printing both
new.clear()
print('new: ', new)
print('original: ', original)

输出：

new:  {}
original:  {1: 'geeks', 2: 'for'}
new:  {}
original:  {}