# filter

def is_odd(n):

return n % 2 == 1

list(filter(is_odd, [1, 2, 34, 4, 5, 6, 7, 8]))

def not_empty(s):

return s and s.strip()

list(filter(not_empty, ['A', 'B', 'C', '', 'D', ' ', 'E']))

# 素数

def _odd_iter():

n = 1

while True:

n += 2

yield n

def _not_divisible(n):

return lambda x: x % n > 0

def primes():

yield 2

it = _odd_iter()

while True:

n = next(it)

yield n

it = filter(_not_divisible(n), it)

# 打印1000以内的素数:

for n in primes():

if n < 10:

print(n)

else:

break

# 回数是指从左向右读和从右向左读都是一样的数，例如12321，909。请利用filter()筛选出回数：

def is_palindrome(n):

L = [i for i in str(n)]

return L == L[::-1]

def is_palindrome_1(n):

if str(n) == str(n)[::-1]:

return n

# 测试:

output = filter(is_palindrome_1, range(1, 100))

print('1~100:', list(output))