How do I merge two dictionaries in a single expression in Python?

Better Stack Team
Updated on January 24, 2023

To merge two dictionaries in a single expression you can use the dictionary unpacking operator **. This creates a new dictionary and unpacks all key-value pairs into the new dictionary. Let’s look at the example below.

x = {'firstname': 'John'}
y = {'lastname': 'Doe'}

z = {**x,**y}

This will create a new dictionary z with the value of {'firstname': 'John', 'lastname': 'Doe'}.

Using OR operator

If you are using python 3.9.0 or greater, you can also use the bitwise OR operator also known as a pipe operator.

z = x | y

The result will be the same.

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