What Is List And Dictionary Comprehension In Python?

What Is List And Dictionary Comprehension In Python?

Published on October 07 2023
In this tutorial, we will learn what is a list and dictionary comprehension with detailed explanations and examples. This tutorial is part of Python's top 25 most commonly asked interview questions.

Definition

  • provide a more compact and elegant way to create lists and dictionaries based on existing iterable.
  • Comprehension saves a lot of time and code that might be considerably more complex and time-consuming.
  • In simple words if you say it combines your loop and conditional statement in one line.

Type

  • List Comprehension
# Syntax For List Comprehension

a for a in iterator OR a for a in iterator if condition
  • Dictionary Comprehension
# Syntax for Dictionary Comprehension

{ key: expression for an item in iterator }

Benefits

  • Performing mathematical operations on the entire list and dictionary.
  • Performing conditional filtering operations on the entire list and dictionary.
  • Combining multiple lists into one

Example List Comprehension

my_list = [2, 3, 5, 7, 11]
even_squared_list = [x**2 for x in my_list if x % 2 == 0]

Output

[4]

Example Dict Comprehension

my_list = [2, 3, 5, 7, 11]
squared_dict = { x:x**2 for x in my_list }

Output

{2: 4, 3: 9, 5: 25, 7: 49, 11: 121}

To know about it, please refer to the official documentation website - official website.



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