Append a Key to a Python Dictionary

We can append or add and update the value of key in dictionary using various methods. In this article, we will explore three different methods to achieve this task: Using update() method, Using merge operator (“|”), Using update operator(“|=”), Adding key with value, Adding key without value.

Example :

Input: Dictionary ={ 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8} 
             Key = Python, value = 6

Output: { 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8, 'Python':6} 

How to Append a Key to a Dictionary Python?

Below are the methods of How to Append a Key to a Dictionary in Python.

• Adding Key with Value
• Using update() Method
• Using setdefault() Method
• Using dict Constructor

Append a Key to a Dictionary by Adding Key with Value

In this example, below code initializes a dictionary with predefined key-value pairs and then adds a new key “Python” with the value 6 to the dictionary before printing the updated dictionary.

Python3

Dictionary ={ 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}
key = "Python"
value = 6

# adding key and value to dictionary
Dictionary[key]=value
print(Dictionary)

Output

{'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8, 'Python': 6}

Append a Key to a Dictionary Python Using Update() Method

In this example, The code merges `Dictionary_2` into `Dictionary_1` using the `update()` method, adding the key “Python” with the value 6 to the original dictionary, and prints the updated result.

Python3

Dictionary_1 ={ 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}
Dictionary_2 = {'Python':6}

#adding key to dictionary using update method
Dictionary_1.update(Dictionary_2)
print(Dictionary_1)

Output

{'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8, 'Python': 6}

Append a Key to a Dictionary Python Using setdefault() Method

In this example, below code initializes a dictionary, `my_dict`, and uses the `setdefault()` method to add a new key-value pair (‘Python’, 6). If ‘Python’ is not already a key, it is added with the value 6. The updated dictionary is printed.

Python3

# Example dictionary
my_dict = { 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}

# Using the setdefault() method to add a new key-value pair
my_dict.setdefault('Python', 6)

# Displaying the updated dictionary
print(my_dict)

Output

{'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8, 'Python': 6}

Append a Key to a Dictionary Python Using dict Constructor

In this example, below code initializes a dictionary, `my_dict`, and uses the `dict` constructor to add a new key-value pair (‘Python’, 6). The existing key-value pairs from `my_dict` are combined with the new pair, creating an updated dictionary. The result is then printed.

Python3

# Example dictionary
my_dict = { 'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8}

# Using the dict constructor to add a new key-value pair
my_dict = dict(my_dict, Python=6)

# Displaying the updated dictionary
print(my_dict)

Output

{'gfg': 3, 'geeks': 5, 'for': 2, 'geek': 4, 'tutorial': 8, 'Python': 6}