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

By Bhavani

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πŸ‘‰Python Dictionary Append

πŸ‘‰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.


πŸ‘‰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}

  1. 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)

 βŒ Incorrect Example:

python

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


πŸ‘‰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:

πŸ‘‰Example: Append Elements Using .append()

Consider the following dictionary:

python

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

πŸ‘‰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)

πŸ‘‰Output:

bash

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


πŸ‘‰Accessing Elements in a Python Dictionary

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

πŸ‘‰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’])

πŸ‘‰Output:

makefile

username: XYZ

email: xyz@gmail.com

location: Mumbai


πŸ‘‰Handling Key Errors in Python Dictionary

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

πŸ‘‰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.”)

πŸ‘‰Output:

pgsql

Key not found in dictionary.


πŸ‘‰Best Practices for Appending in Dictionaries

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

πŸ‘‰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

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