How to merge two dictionaries in Python?

Table of Contents

• Introduction
• Methods to Merge Two Dictionaries
  • 1. Using the update() Method
  • Example:
  • Example: Merging Without Modifying Original Dictionary
  • 2. Using Dictionary Unpacking (Python 3.5+)
  • Example:
  • Example: Merging Multiple Dictionaries
  • 3. Using dict() Constructor with ** Unpacking
  • Example:
  • 4. Using the | Operator (Python 3.9+)
• Example:
• Practical Examples
  • Example : Merging Dictionaries with Default Values
  • Example : Combining Configuration Settings
  • Example : Merging Lists of Dictionaries
• Conclusion

Introduction

Merging dictionaries in Python is a common operation when combining data from multiple sources. Python provides several methods to merge dictionaries, each suitable for different scenarios. This guide explains how to merge two dictionaries using various techniques and provides practical examples.

Methods to Merge Two Dictionaries

1. Using the update() Method

• update() Method: The update() method updates the dictionary with elements from another dictionary. If the same key exists in both dictionaries, the value from the second dictionary will overwrite the value from the first.

Example:

Example: Merging Without Modifying Original Dictionary

2. Using Dictionary Unpacking (Python 3.5+)

• Dictionary Unpacking: From Python 3.5 onwards, you can use the ** operator to unpack dictionaries and merge them into a new dictionary. This method provides a clean and concise way to merge dictionaries.

Example:

Example: Merging Multiple Dictionaries

3. Using dict() Constructor with ** Unpacking

• dict() Constructor: Another way to merge dictionaries is by using the dict() constructor with the ** unpacking method. This is useful when you need to create a dictionary from multiple sources.

Example:

4. Using the | Operator (Python 3.9+)

• | Operator: From Python 3.9 onwards, you can use the | operator to merge dictionaries. This operator creates a new dictionary with the combined keys and values from the dictionaries being merged.

Example:

Practical Examples

Example : Merging Dictionaries with Default Values

Example : Combining Configuration Settings

Example : Merging Lists of Dictionaries

Conclusion

Merging dictionaries in Python can be done using several methods, including the update() method, dictionary unpacking, the dict() constructor, and the | operator. Each method has its use cases, providing flexibility in how you combine and manage dictionary data. Understanding these methods allows you to efficiently handle dictionary merging tasks in Python.