How to use filter function in Python

The filter() function in Python is used to filter items from any iterable (list, tuple, dictionary etc.) based on a condition defined by a function. The filter() function returns a new iterable (iterator) that can be used to iterate over the items that satisfy the condition. The general syntax of filter() function is as follows:

filter(function, iterable)

Here, function is the function that needs to be applied to each element of the iterable, and iterable is the sequence that needs to be filtered. The function should return True or False for each element of the iterable, based on which the filtering is done.

Here’s an example that demonstrates how to use the filter() function in Python:

def is_even(num):
    return num % 2 == 0

my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
even_numbers = list(filter(is_even, my_list))

print(even_numbers)   # Output: [2, 4, 6, 8, 10]

In this example, we define a function is_even that takes a number as input and returns True if the number is even. We then define a list my_list containing some numbers (from 1 to 10). We use the filter() function to filter the even numbers from the list my_list using the is_even() function. Finally, we convert the result into a list and print it.

In this way, you can use the filter() function to filter items from any iterable based on a condition.