“How to use list comprehension in Python?”

List comprehensions are a concise and efficient way to create, manipulate, and filter lists. Using list comprehensions in Python is very simple, as you just need to write them in a specific syntax.

The basic syntax format for list comprehensions is as follows:

[expression for variable in list if condition]

Expressions can be any valid Python expression, variables are temporary variables used for iterating through the list, the list is the source list to be iterated through, and the condition is an optional filtering condition.

Here are a few examples of using list comprehension:

1. Create a list containing all the even numbers between 1 and 10:

even_numbers = [i for i in range(1, 11) if i % 2 == 0]
print(even_numbers)  # [2, 4, 6, 8, 10]

1. Multiply each element in the list by 2.

numbers = [1, 2, 3, 4, 5]
double_numbers = [x * 2 for x in numbers]
print(double_numbers)  # [2, 4, 6, 8, 10]

1. Filter out the negative numbers from the list.

numbers = [1, -2, 3, -4, 5]
negative_numbers = [x for x in numbers if x < 0]
print(negative_numbers)  # [-2, -4]

1. Creating a two-dimensional list using multiple loops.

matrix = [[i * j for i in range(1, 4)] for j in range(1, 4)]
print(matrix)  # [[1, 2, 3], [2, 4, 6], [3, 6, 9]]

In summary,

By utilizing concise syntax, list comprehensions can quickly create, manipulate, and filter lists. Mastering list comprehensions can help improve the readability and execution efficiency of code.