Python filter() function

Python filter() function

The filter() function constructs an iterator from those elements of iterable for which the parameter ‘function’ returns a Boolean value true.

Syntax

filter(function, iterable)

Parameter

function: This parameter represents a function to be run for each item in the iterable

Iterable:  It represents the iterable to be filtered

Return

This function returns an iterator where the items are filtered through a function to test if the item is accepted or not.

Example 1

#Python program explaining
# the filter() function
voters_age = [5, 12, 17, 18, 24, 32]
def validAge(age):
  if age < 18:
    return False
  else:
    return True
#applying the filter() function
adults = filter(validAge, voters_age)
for age in adults:
  print(age)

Output

18
24
32

 

Example 2

#Python program explaining
# the filter() function
# a list contains both even and odd numbers. 
values = [10, 11, 12, 13, 15, 18, 103]
print("List: ",values)
# filter() returning odd numbers of the list
even_val = filter(lambda x: x % 2!=0, values)
print("Even Values: ",list(even_val))
# filter() returning even numbers of the list
odd_val = filter(lambda x: x % 2 == 0, values)
print("Odd values: ",list(odd_val))

Output

List:  [10, 11, 12, 13, 15, 18, 103]
Even Values:  [11, 13, 15, 103]
Odd values:  [10, 12, 18]