数据筛选器的用途广泛，比如我们要从一堆随机数中筛选出奇数或者偶数，比如我们要从一组学生证筛选出所有年龄大于10岁的女同学，等等。

下面的示例代码演示了如何快速方便的实现数据筛选器：

import random

numbers = []
for i in range(10):
    n = random.randint(1, 100)
    numbers.append(n)

print(numbers)

odds = [n for n in numbers if n % 2 == 1]
print(odds)

evens = (n for n in numbers if n % 2 == 0)
print(evens)
for e in evens:
    print(e)
    
prices = {
          'apple':13.5,
          'banana':6.0,
          'pear': 6.8,
          'orange': 9.9
          }

p1 = {key:value for key, value in prices.items() if value < 10}
print(p1)

favourites = ['banana', 'pear']
p2 = {key:value for key, value in prices.items() if key in favourites}
print (p2)