The **`filter()` function** facilitates a functional approach to Python programming. It takes as an argument a *function* and an *iterable* and applies the passed function to each element of the iterable. Once this is done, it returns an *iterable*.

The `filter()` function is similar to a for-loop in Python but is much fast as a built-in function.

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# Syntax
Here is the function signature for the `filter()` function in Python:


# function signature for the filter() method
returned_iterable = filter(function, iterable)

As described above, the `filter()` function takes the following two arguments as input:

- **`function`:** A valid, pre-defined function. This is a [lambda function](https://www.educative.io/answers/what-is-a-python-lambda-function) in most cases.

- **`iterable`:** This is an iterable object (e.g. list, tuple, dictionary). 

**Returned:** An iterator to the *filtered* items' iterable object.

# Examples

Let's take a look at a couple of examples of how the `filter()` method works:

## 1. Using a lambda function


myList = [10, 25, 17, 9, 30, -5]
# Returns the elements which are multiples of 5
myList2 = list(filter(lambda n : n%5 == 0, myList))
print(myList2)

# Returns the elements which are multiples of 5
def multipleOf5(n):
  if(n % 5 == 0):
    return n
myList = [10, 25, 17, 9, 30, -5]
myList2 = list(filter(multipleOf5, myList))
print(myList2)

How to use the filter() method in Python

The filter() function facilitates a functional approach to Python programming. It takes as an argument a function and an iterable and applies the passed function to each element of the iterable. Once this is done, it returns an iterable. The filter() function is similar to a for-loop in Python but is much fast as a built-in function.  Syntax Here is the function signature for the filter() function in Python: 

How to use the filter() method in Python

Syntax

Examples

1. Using a lambda function

2. Using a pre-defined function