Python Dictionary Append : How to Add Key/Value Pairs with Examples Best Step-by-Step Guide 2025

👉Python Dictionary Append

👉Introduction

Python Dictionary Append:

A Python Dictionary is a crucial data type that stores data in key-value pairs. Each key-value pair is separated by a colon : and each pair is divided by a comma ,.

For example:

python

my_dict = {“a”: “A”, “b”: “B”, “c”: “C”, “d”: “D”}

Dictionaries provide a powerful way to organize and manage data. Let’s explore how to append values to dictionary keys effectively.

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👉Restrictions on Dictionary Keys

Python Dictionary Append: Before learning to append elements, it’s important to understand the key rules for dictionaries:

Python Dictionary Append Unique Keys: Dictionary keys must be unique. If a duplicate key is defined, the last declared value will overwrite the previous one.

python

my_dict = {“Name”: “ABC”, “Address”: “Mumbai”, “Age”: 30, “Name”: “XYZ”}

print(my_dict)

# Output: {‘Name’: ‘XYZ’, ‘Address’: ‘Mumbai’, ‘Age’: 30}

2. Allowed Data Types for Keys:
   
   • Keys can be numbers, strings, floats, booleans, tuples, and even built-in objects like classes and functions.
   • Keys cannot be defined using mutable data types like lists.

python

my_dict = {bin: “001”, hex: “6”, 10: “ten”, bool: “1”, float: “12.8”, int: 1, False: “0”}

print(my_dict)

 ❌ Incorrect Example:

python

my_dict = {[“Name”]: “ABC”}  # This will raise an error

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👉How to Append Elements to a Dictionary Key in Python

Python Dictionary Append: Python’s .append() method allows you to add elements to list-type values inside a dictionary. Here’s how you can do it:

👉Example: Append Elements Using .append()

Consider the following dictionary:

python

my_dict = {“Name”: [], “Address”: [], “Age”: []}

👉Appending Values to Dictionary Keys

python

my_dict[“Name”].append(“Software Moji”)

my_dict[“Address”].append(“Mumbai”)

my_dict[“Age”].append(30)

print(my_dict)

👉Output:

bash

{‘Name’: [‘Software Moji’], ‘Address’: [‘Mumbai’], ‘Age’: [30]}

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👉Accessing Elements in a Python Dictionary

To access values in a dictionary, use square brackets with the key inside.

👉Example: Access Dictionary Elements

python

my_dict = {“username”: “XYZ”, “email”: “xyz@gmail.com”, “location”: “Mumbai”}

print(“username:”, my_dict[‘username’])

print(“email:”, my_dict[’email’])

print(“location:”, my_dict[‘location’])

👉Output:

makefile

username: XYZ

email: xyz@gmail.com

location: Mumbai

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👉Handling Key Errors in Python Dictionary

If you attempt to access a key that does not exist, Python will raise a KeyError.

👉Example: KeyError Handling

python

my_dict = {“username”: “XYZ”, “email”: “xyz@gmail.com”, “location”: “Mumbai”}

try:

    print(“name:”, my_dict[‘name’])

except KeyError:

    print(“Key not found in dictionary.”)

👉Output:

pgsql

Key not found in dictionary.

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👉Best Practices for Appending in Dictionaries

✅ Always initialize dictionary keys with list values if you plan to append data.
✅ Use .get() to safely access dictionary keys without risking KeyError.

👉Example: Using .get() for Safe Access

python

my_dict = {“Name”: [“Alice”], “Age”: [25]}

# Append safely using `.get()` method

my_dict.get(“Name”, []).append(“Bob”)

print(my_dict)  

# Output: {‘Name’: [‘Alice’, ‘Bob’], ‘Age’: [25]}

Python Dictionary Tutorial