Python filter()函数

filter(function, iterable)

def is_positive(x):
    return x > 0

numbers = [-2, 3, 5, -1, 0, 9]
positive_numbers = list(filter(is_positive, numbers))

print(positive_numbers)

[3, 5, 9]

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
even_numbers = list(filter(lambda x: x % 2 == 0, numbers))

print(even_numbers)

[2, 4, 6, 8, 10]

def not_empty(s):
    return s and s.strip()

strings = ['hello', '', 'world', ' ', 'python', '']
non_empty_strings = list(filter(not_empty, strings))

print(non_empty_strings)

['hello', 'world', 'python']

strings = ['apple', 'banana', 'carrot', 'kiwi', 'pear']
long_strings = list(filter(lambda s: len(s) >= 5, strings))

print(long_strings)

['apple', 'banana', 'carrot']