Python: 从dict字典中删除键的不同方法 del vs dict.pop(), Different ways to Remove a key from Dictionary in Python | del vs dict.pop()

Updated Dictionary : {'Hello': 56, 'test': 43, 'this': 43}

有必要在删除之前检查字典中是否存在密钥，否则请使用throw keyError删除del。

使用del和try / except从字典中删除密钥

如果我们不想在调用del之前添加if if检查，我们也可以使用try / except。让我们尝试删除字典中不存在的键并捕获错误，即

dict.pop(key[, default])

• 如果字典中存在键，则dict.pop（）从字典中删除具有给定键的元素并返回其值。
• 如果字典中不存在给定的键，则它将返回给定的默认值。
• 如果字典中不存在给定键，并且没有将默认值传递给pop（），它将抛出KeyError

让我们使用pop()从dict中删除一个元素

''' 
Deleting an entry from dictionary using pop() 
'''    
 
# As 'this' key is present in dict, so pop() will delete its entry and return its value    
result = wordFreqDic.pop("this", None)    
 
print("Deleted item's value = ", result)
print("Updated Dictionary :" , wordFreqDic)

输出：

Deleted item's value =  43
Updated Dictionary : {'Hello': 56, 'test': 43}

key not found

完整的示例如下：

def main():
    
    # Dictionary of strings and int
    wordFreqDic = {
        "Hello": 56,
        "at" : 23 ,
        "test" : 43,
        "this" : 43
        }
    
    print("Original Dictionary :" , wordFreqDic)   
    
    
    ''' 
    Deleting an entry from dictionary using del 
    '''
    # If key exist in dictionary then delete it using del.
    if "at" in wordFreqDic:
        del wordFreqDic["at"]
        
    print("Updated Dictionary :" , wordFreqDic)      
    
    
    ''' 
    Deleting an entry from dictionary using del and try/except  
    '''
    # If key is not present in dictionary, then del can throw KeyError
    try:
        del wordFreqDic["testing"]
    except KeyError:
        print("Key 'testing' not found")
        
    
    ''' 
    Deleting an entry from dictionary using pop() 
    '''    
    
    # As 'this' key is present in dict, so pop() will delete its entry and return its value    
    result = wordFreqDic.pop("this", None)    
    
    print("Deleted item's value = ", result)
    print("Updated Dictionary :" , wordFreqDic)   
        
    
    # Trying to delete an element from dict, which is not present.
    # It will return given default value i.e. None     
    result = wordFreqDic.pop("testing", None)    
    
    print("Deleted item's value = ", result)
    print("Updated Dictionary :" , wordFreqDic)   
    
    
    # Trying to delete an element from dict, which is not present.
    # Also, if we don't pass any default value then it will throw KeyError.     
    
    try:
        wordFreqDic.pop("testing")    
    except KeyError:
        print("Key not found")    
    
            
    
    
if __name__ == '__main__':
    main()

Original Dictionary : {'this': 43, 'at': 23, 'Hello': 56, 'test': 43}
Updated Dictionary : {'this': 43, 'Hello': 56, 'test': 43}
Key 'testing' not found
Deleted item's value =  43
Updated Dictionary : {'Hello': 56, 'test': 43}
Deleted item's value =  None
Updated Dictionary : {'Hello': 56, 'test': 43}
Key not found