Python字典 update() 方法

Python Dictionary update() 方法使用来自另一个字典对象或可迭代的键/值对的元素更新字典。

Syntax: dict.update([other])

Parameters: This method takes either a dictionary or an iterable object of key/value pairs (generally tuples) as parameters.

Returns: It doesn’t return any value but updates the Dictionary with elements from a dictionary object or an iterable object of key/value pairs.

Python字典 update() 示例

示例 #1：使用另一个字典进行更新

Python3

# Python program to show working
# of update() method in Dictionary
 
# Dictionary with three items
Dictionary1 = {'A': 'Geeks', 'B': 'For', }
Dictionary2 = {'B': 'Geeks'}
 
# Dictionary before Updation
print("Original Dictionary:")
print(Dictionary1)
 
# update the value of key 'B'
Dictionary1.update(Dictionary2)
print("Dictionary after updation:")
print(Dictionary1)

输出：

Original Dictionary:
{'A': 'Geeks', 'B': 'For'}

Dictionary after updation:
{'A': 'Geeks', 'B': 'Geeks'}

示例 #2：使用可迭代更新

Python3

# Python program to show working
# of update() method in Dictionary
 
# Dictionary with single item
Dictionary1 = {'A': 'Geeks'}
 
# Dictionary before Updation
print("Original Dictionary:")
print(Dictionary1)
 
# update the Dictionary with iterable
Dictionary1.update(B='For', C='Geeks')
print("Dictionary after updation:")
print(Dictionary1)

输出：

Original Dictionary:
{'A': 'Geeks'}

Dictionary after updation:
{'C': 'Geeks', 'B': 'For', 'A': 'Geeks'}

示例 #3：如果键存在，则Python字典更新值

Python3

def checkKey(dict, key):
       
    if key in dict.keys():
        print("Key exist, ", end =" ")
        dict.update({'m':600})
        print("value updated =", 600)
    else:
        print("Not Exist")
dict = {'m': 700, 'n':100, 't':500}
   
key = 'm'
checkKey(dict, key)
print(dict)

输出：

Key exist,  value updated = 600
{'m': 600, 'n': 100, 't': 500}