Intersecting two dictionaries in Python

August 16, 2021

Intersecting two dictionaries in Python

Dictionary is an unordered collection of data in the form of key-value pairs separated by commas inside curly brackets. Dictionaries are indexed by keys. They are generally optimized to retrieve values when the key is known. Values (definitions) are mapped to a specific key (words) similar to that of a dictionary in the real world.

Now our task is intersecting two dictionaries using their keys. We can achieve this in two ways

Dictionary Comprehension
& Operator

Using Dictionary Comprehension:

Before we move on to learn this method, please refer to this article about Dictionary Comprehension for better understanding.

https://docs.google.com/document/d/13bMIsQim-pDQTk2crKPrbxSGlvGKqt_8ZU_UMGo8MqI/edit?usp=sharing (To be replaced with the article link to i2tutorials website)

Now, let’s take an example of two dictionaries x and y with the following keys and values.

We now take an iterator i which is the key of x and check whether the i(key) in x exists in y as well by running a for loop.

 { i : x[i] for i in x if i in y }

If it finds one, the common key and its value are pushed inside a new dictionary named z.

z = { i : x[i] for i in x if i in y }

We can see the common key:value pair {‘a’: ‘one’} has been printed when we tried to print z.

Using &(AND) Operator:

Let’s consider the same example of two dictionaries x and y. We now try to convert the two dictionaries into a list using the items() function and relate them using the &(AND) Operator.