filter function python code example

Example 1: python filter

number_list = range(-5, 5)
less_than_zero = list(filter(lambda x: x < 0, number_list))
print(less_than_zero)

# Output: [-5, -4, -3, -2, -1]

Example 2: python filter

ages = [5, 12, 17, 18, 24, 32]
def myFunc(x):
  if x < 18:
    return False
  else:
    return True
  
adults = filter(myFunc, ages)
for x in adults:
  print(x)     		# 18 24 32

Example 3: what are filters in python

In simple words, the filter() method filters the given iterable 
with the help of a function that tests
each element in the iterable to be true or not.

Filter Methods is simply a like comprarator class of c++ STL


Code Explanation: 
  # A simple tutorial to show the filter 
# methods in python

grades = ['A','B','C','F']

def remove_fails(grades):
    return grades!='F'

print(list(filter(remove_fails,grades)))

Example 4: filter function in python

nums1 = [2,3,5,6,76,4,3,2]

def bada(num):
    return num>4 # bada(2) o/p: False, so wont return.. else anything above > value returns true hence filter function shows result  

filters = list(filter(bada, nums1))
print(filters)
 
(or) 
 
bads = list(filter(lambda x: x>4, nums1))
print(bads)

Example 5: filter function in python

# filter is just filters things

my_list = [1, 2, 3, 4, 5, 6, 7]


def only_odd(item):
    return item % 2 == 1	# checks if it is odd or even


print(list(filter(only_odd, my_list)))

Example 6: python - filter function

# Filter function
def with_s(student):
    return student.startswith('s')

students = ['sarah', 'mary', 'sergio', 'lucy']   # define a list
s_filter = filter(with_s, students)              # filter() returns true or false
print(next(s_filter))                            # filter() returns a generator
print(list(s_filter))                            # give all elements of the generator