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list comprehension in python
List comprehension is a powerful and concise way to create a new list 📝📝. This lesson post covers its syntax 📃, usage 💻, and best practices.
What is List Comprehension?
List comprehension could be a quick and exquisite way to form a new list in Python by iterating over an existing iterable, such as a list, tuple, string, or range, and applying a few changes or filtering to its elements. It permits you to write code more expressively and can spare time and exertion.
List comprehension has a simple and elegant syntax that consists of three parts:
new_list = [expression for variable in iterable if condition]
The for loop and the if statement are the two fundamental building blocks of list comprehension. The for loop iterates over the iterable object, and the if statement filters the elements based on a condition.
Let's see some examples of list comprehension in action.
Creating a new list of squared values
numbers = [1, 2, 3, 4, 5] squared_numbers = [y**2 for y in numbers] print(squared_numbers)
In this example, we're creating a new list called squared_numbers that contains the squared values of the elements in the numbers list.
Filtering elements in a list
numbers = [1, 2, 3, 4, 5] even_numbers = [y for y in numbers if x % 2 == 0] print(even_numbers)
In this example, we're creating a new list called even_numbers that contains only the even numbers from the numbers list.
Nested list comprehension
matrix = [[1, 2], [3, 4], [5, 6]] flattened_matrix = [element for row in matrix for element in row] print(flattened_matrix)
In this example, we're creating a new list called flattened_matrix that contains all the elements in the matrix list. We're using a nested list comprehension with two for loops to achieve this.
Here are some best practices to follow when using list comprehension in your code:
List comprehension is a powerful and elegant feature of Python that allows you to create new lists easily. It can help you write more concise and readable code and save you time and effort. Following best practices and using list comprehension effectively can make your Python code more efficient and expressive.
Answer: b. A way to create a new list by iterating over an existing iterable and applying some transformation or filtering to its elements.
Answer: b. For loop and if statement
Answer: c. To make the code easier to understand
Answer:c. Use meaningful variable names and keep it simple