Dictionary in Python is an unordered collection of data values, used to store data values like a map, which unlike other Data Types that hold only single value as an element, Dictionary holds key:value pair. While using Dictionary, sometimes, we need to add or modify the key/value inside the dictionary. Let’s see how to add a key:value pair to dictionary in Python.
Code #1: Using Subscript notation This method will create a new key:value pair on a dictionary by assigning a value to that key.
Python3
# Python program to add a key:value pair to dictionarydict = {'key1':'Lazyroar', 'key2':'for'}print("Current Dict is: ", dict) # using the subscript notation# Dictionary_Name[New_Key_Name] = New_Key_Valuedict['key3'] = 'Geeks'dict['key4'] = 'is'dict['key5'] = 'portal'dict['key6'] = 'Computer'print("Updated Dict is: ", dict) |
Current Dict is: {‘key2’: ‘for’, ‘key1’: ‘Lazyroar’} Updated Dict is: {‘key3’: ‘Geeks’, ‘key5’: ‘portal’, ‘key6’: ‘Computer’, ‘key4’: ‘is’, ‘key1’: ‘Lazyroar’, ‘key2’: ‘for’}
Time Complexity: O(1)
Auxiliary Space: O(1)
Code #2: Using update() method
Python3
dict = {'key1':'Lazyroar', 'key2':'for'}print("Current Dict is: ", dict)# adding dict1 (key3, key4 and key5) to dictdict1 = {'key3':'Lazyroar', 'key4':'is', 'key5':'fabulous'}dict.update(dict1)# by assigningdict.update(newkey1 ='portal')print(dict) |
Current Dict is: {‘key2’: ‘for’, ‘key1’: ‘Lazyroar’} {‘newkey1’: ‘portal’, ‘key4’: ‘is’, ‘key2’: ‘for’, ‘key1’: ‘Lazyroar’, ‘key5’: ‘fabulous’, ‘key3’: ‘Lazyroar’}
Time Complexity: O(1)
Auxiliary Space: O(1)
Code #3: Taking Key:value as input
Python3
# Let's add key:value to a dictionary, the functional way# Create your dictionary classclass my_dictionary(dict): # __init__ function def __init__(self): self = dict() # Function to add key:value def add(self, key, value): self[key] = value# Main Functiondict_obj = my_dictionary()# Taking input key = 1, value = Geekdict_obj.key = input("Enter the key: ")dict_obj.value = input("Enter the value: ")dict_obj.add(dict_obj.key, dict_obj.value)dict_obj.add(2, 'forGeeks')print(dict_obj) |
Output:
{'1': 'Geeks', 2: 'forGeeks'}
Time Complexity: O(1)
Auxiliary Space: O(n)
Code #4: Using a dictionary comprehension
For example, you can create a new dictionary that adds a key:value pair to an existing dictionary like this:
Python3
existing_dict = {'key1': 'value1', 'key2': 'value2'}new_key = 'key3'new_value = 'value3'updated_dict = {**existing_dict, new_key: new_value}print(updated_dict)#This code is contributed by Edula Vinay Kumar Reddy |
{'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}
This creates a new dictionary called updated_dict that contains all the key:value pairs from existing_dict, as well as the new key:value pair ‘key3’: ‘value3’.
Time Complexity: O(n)
Auxiliary Space: O(n)
