How to Concat Dict in Python?

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Recently, during a live webinar, someone asked about concatenating a dictionary in Python. There are various methods to do this in Python. In this tutorial, I will explain how to contact dict in Python using different methods with examples.

To concatenate dictionaries in Python using the update() method, simply call the update() function on the first dictionary and pass the second dictionary as an argument. This method modifies the first dictionary in place by adding or updating its key-value pairs with those from the second dictionary. For example, dict1.update(dict2) will merge dict2 into dict1, resulting in a combined dictionary containing elements from both.

Concat Dict in Python

Dictionary concatenation involves combining two or more dictionaries into a single dictionary. This is particularly useful when merging data from multiple sources or updating existing dictionaries with new information.

Now let me show you various methods for concatenating dictionaries in Python.

1. Using the update() Method

The update() method is one of the simplest ways to concatenate dictionaries in Python. It updates the dictionary with elements from another dictionary.

Syntax:

Here is the syntax:

dict1.update(dict2)

Example:

Here is an example.

config1 = {'host': 'localhost', 'port': 8080} config2 = {'database': 'test_db', 'user': 'admin'} config1.update(config2) print(config1)

Output:

{'host': 'localhost', 'port': 8080, 'database': 'test_db', 'user': 'admin'}

You can see the exact output in the screenshot below:

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2. Using the | Operator (Python 3.9+)

Python 3.9 introduced the merge operator |, which allows you to concatenate dictionaries in a single line.

Syntax:

Here is the syntax:

dict3 = dict1 | dict2

Example:

Now, let me show you a complete example.

user_info1 = {'name': 'John Doe', 'age': 30} user_info2 = {'city': 'New York', 'email': 'john.doe@example.com'} user_info_combined = user_info1 | user_info2 print(user_info_combined)

Output:

{'name': 'John Doe', 'age': 30, 'city': 'New York', 'email': 'john.doe@example.com'}

Here is the exact output in the screenshot below:

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3. Using Dictionary Unpacking (** Operator)

Dictionary unpacking is another elegant way to concatenate dictionaries. This method is available in Python 3.5+.

Syntax:

Here is the syntax:

dict3 = {**dict1, **dict2}

Example:

Now, let me show you an example.

employee_data1 = {'employee_id': 101, 'name': 'Alice'} employee_data2 = {'department': 'HR', 'location': 'San Francisco'} employee_data_combined = {**employee_data1, **employee_data2} print(employee_data_combined)

Output:

{'employee_id': 101, 'name': 'Alice', 'department': 'HR', 'location': 'San Francisco'}

Read Python Dictionary Count

4. Using the ChainMap Class from collections

The ChainMap class from the collections module can be used to concatenate dictionaries. This method is particularly useful when you want to work with multiple dictionaries as a single unit without actually merging them.

Syntax:

Here is the syntax:

from collections import ChainMap combined_dict = ChainMap(dict1, dict2)

Example:

Here is an example and the complete Python code.

settings1 = {'theme': 'dark', 'language': 'English'} settings2 = {'timezone': 'EST', 'notifications': 'enabled'} combined_settings = ChainMap(settings1, settings2) print(combined_settings)

Output:

ChainMap({'theme': 'dark', 'language': 'English'}, {'timezone': 'EST', 'notifications': 'enabled'})

Read Python Dictionary Update

5. Using a Loop

For more control over the concatenation process, you can use a loop to iterate through the dictionaries and merge them manually.

Syntax:
Below is the syntax:

for key, value in dict2.items(): dict1[key] = value

Example:

Let me show you an example.

preferences1 = {'color': 'blue', 'font_size': 12} preferences2 = {'font_size': 14, 'layout': 'grid'} for key, value in preferences2.items(): preferences1[key] = value print(preferences1)

Output:

{'color': 'blue', 'font_size': 14, 'layout': 'grid'}

Here is the output in the screenshot below:

Conclusion

In this tutorial, I explained how to concatenate dictionaries in Python using various methods, such as the update() method, the elegance of the | operator, etc.