Complementary function filterfalse, ifilterfalse

There is a complementary function for filter in the itertools-module:

# not recommended in real use but keeps the example valid for python 2.x and python 3.x
from itertools import ifilterfalse as filterfalse

from itertools import filterfalse

which works exactly like the generator filter but keeps only the elements that are False:

# Usage without function (None):
list(filterfalse(None, [1, 0, 2, [], '', 'a']))  # discards 1, 2, 'a' 
# Out: [0, [], '']

Usage with function

names = [‘Fred’, ‘Wilma’, ‘Barney’]

def long_name(name):
	return len(name) > 5

list(filterfalse(long_name, names)) # Out: [‘Fred’, ‘Wilma’]

Short-circuit usage with next:

car_shop = [('Toyota', 1000), ('rectangular tire', 80), ('Porsche', 5000)]
def find_something_smaller_than(name_value_tuple):
    print('Check {0}, {1}$'.format(*name_value_tuple)
    return name_value_tuple[1] < 100
next(filterfalse(find_something_smaller_than, car_shop))
# Print: Check Toyota, 1000$
# Out: ('Toyota', 1000)

Using an equivalent generator:

car_shop = [('Toyota', 1000), ('rectangular tire', 80), ('Porsche', 5000)] 
generator = (car for car in car_shop if not car[1] < 100)
next(generator)

Found a mistake? Have a question or improvement idea? Let me know.

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