How to Add Key Value Pair to Dictionary in Python

September 30, 2024

To add a key-value pair to a dictionary in Python, you can use three different methods.

The following examples show how to add a key-value pair to a dictionary in Python.

Using = Operator

We can use the assignment (=) operator to add a key-value pair to a dictionary.

Suppose we have the following dictionary:

# Declare dictionary
dict1 = {"A": 25, "B": 27, "C": 45}

# Add key-value pair
dict1["D"] = 36

# Show updated dictionary
print("Updated dictionary:", dict1)

Output: 👇️

Updated dictionary: {'A': 25, 'B': 27, 'C': 45, 'D': 36}

In this example, we use the assignment (=) operator to add the key-value pair “D”: 36 to the dictionary.

Using update() Function

We can use the update() function to add a key-value pair to a dictionary.

Suppose we have the same dictionary as above.

We can use the following code to add the key-value pair “D”: 36 to the dictionary:

# Add key-value pair
dict1.update({"D": 36})

# Show updated dictionary
print("Updated dictionary:", dict1)

Output: 👇️

Updated dictionary: {'A': 25, 'B': 27, 'C': 45, 'D': 36}

In this example, we use the update() function to add the key-value pair “D”: 36 to the dictionary.

Using setdefault() Function

We can use the setdefault() function to add a key-value pair to a dictionary.

Suppose we have the same dictionary as above.

We can use the following code to add the key-value pair “D”: 36 to the dictionary:

# Add key-value pair
dict1.setdefault("D", 36)

# Show updated dictionary
print("Updated dictionary:", dict1)

Output: 👇️

Updated dictionary: {'A': 25, 'B': 27, 'C': 45, 'D': 36}

In this example, we use the setdefault() function to add the key-value pair “D”: 36 to the dictionary.