Python 字典副本()
Python 字典副本()方法返回字典的一个浅副本。
Python 字典副本()语法:
dict.copy()
Python 字典副本()参数:
copy()方法不接受任何参数。
Python 字典副本()返回:
这个方法不修改原字典，只返回字典的副本。
Python 字典副本()示例:
Input : original = {1:'geeks', 2:'for'}
new = original.copy()
Output : original: {1: 'one', 2: 'two'}
new: {1: 'one', 2: 'two'}
Python 字典副本()错误:
As we are not passing any parameters
there is no chance of any error.
示例 1:使用 Python 字典副本()
Python 3
# 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 字典复制()并更新
Python 3
# 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'}
与简单赋值“=”有何不同？
与 copy()不同，赋值运算符执行深度复制。
Python 3
# 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: {}
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