Python | Ways to remove a key from dictionary
Dictionary is used in manifold practical applications such as day-day programming, web development and AI/ML programming as well, making it a useful container overall. Hence, knowing shorthands for achieving different tasks related to dictionary usage always is a plus. This article deals with one such task of deleting a dictionary key-value pair from a dictionary.
Method 1 : Using del
del keyword can be used to inplace delete the key that is present in the dictionary. One drawback that can be thought of using this is that is raises an exception if the key is not found and hence non-existence of key has to be handled.
Code #1 : Demonstrating key-value pair deletion using del
# Python code to demonstrate # removal of dict. pair # using del # Initializing dictionary test_dict = {"Arushi" : 22, "Anuradha" : 21, "Mani" : 21, "Haritha" : 21} # Printing dictionary before removal print ("The dictionary before performing remove is : " + str(test_dict)) # Using del to remove a dict # removes Mani del test_dict['Mani'] # Printing dictionary after removal print ("The dictionary after remove is : " + str(test_dict)) # Using del to remove a dict # raises exception del test_dict['Manjeet'] |
Output :
The dictionary before performing remove is : {'Anuradha': 21, 'Haritha': 21, 'Arushi': 22, 'Mani': 21}
The dictionary after remove is : {'Anuradha': 21, 'Haritha': 21, 'Arushi': 22}
Exception :
Traceback (most recent call last):
File "/home/44db951e7011423359af4861d475458a.py", line 20, in
del test_dict['Manjeet']
KeyError: 'Manjeet'
Method 2 : Using pop()
pop() can be used to delete a key and its value inplace. Advantage over using del is that it provides the mechanism to print desired value if tried to remove a non-existing dict. pair. Second, it also returns the value of key that is being removed in addition to performing a simple delete operation.
Code #2 : Demonstrating key-value pair deletion using pop()
# Python code to demonstrate # removal of dict. pair # using pop() # Initializing dictionary test_dict = {"Arushi" : 22, "Anuradha" : 21, "Mani" : 21, "Haritha" : 21} # Printing dictionary before removal print ("The dictionary before performing remove is : " + str(test_dict)) # Using pop() to remove a dict. pair # removes Mani removed_value = test_dict.pop('Mani') # Printing dictionary after removal print ("The dictionary after remove is : " + str(test_dict)) print ("The removed key's value is : " + str(removed_value)) print ('\r') # Using pop() to remove a dict. pair # doesn't raise exception # assigns 'No Key found' to removed_value removed_value = test_dict.pop('Manjeet', 'No Key found') # Printing dictionary after removal print ("The dictionary after remove is : " + str(test_dict)) print ("The removed key's value is : " + str(removed_value)) |
Output :
The dictionary before performing remove is : {'Arushi': 22, 'Anuradha': 21, 'Mani': 21, 'Haritha': 21}
The dictionary after remove is : {'Arushi': 22, 'Anuradha': 21, 'Haritha': 21}
The removed key's value is : 21
The dictionary after remove is : {'Arushi': 22, 'Anuradha': 21, 'Haritha': 21}
The removed key's value is : No Key found
Method 3 : Using items() + dict comprehension
items() coupled with dict comprehension can also help us achieve task of key-value pair deletion but, it has drawback of not being an inplace dict. technique. Actually a new dict if created except for the key we don’t wish to include.
Code #3 : Demonstrating key-value pair deletion using items() + dict. comprehension
# Python code to demonstrate # removal of dict. pair # using items() + dict comprehension # Initializing dictionary test_dict = {"Arushi" : 22, "Anuradha" : 21, "Mani" : 21, "Haritha" : 21} # Printing dictionary before removal print ("The dictionary before performing remove is : " + str(test_dict)) # Using items() + dict comprehension to remove a dict. pair # removes Mani new_dict = {key:val for key, val in test_dict.items() if key != 'Mani'} # Printing dictionary after removal print ("The dictionary after remove is : " + str(new_dict)) |
Output :
The dictionary before performing remove is : {'Anuradha': 21, 'Haritha': 21, 'Arushi': 22, 'Mani': 21}
The dictionary after remove is : {'Anuradha': 21, 'Haritha': 21, 'Arushi': 22}