python 高阶函数:filter(过滤器)

Posted 2020-12-04

官网解释：

• str.strip([chars])

• Return a copy of the string with the leading and trailing characters removed. The chars argument is a string specifying the set of characters to be removed. If omitted or None, the chars argument defaults to removing whitespace. The chars argument is not a prefix or suffix; rather, all combinations of its values are stripped:

  >>> '   spacious   '.strip()
  'spacious'
  >>> 'www.example.com'.strip('cmowz.')
  'example'

就是，如果省略参数，默认过滤空格。

#过滤list中的偶数

def get_odd(s):
    return s % 2 == 1;   #C语言绝对不能这么写
   
print "get odd:", filter(get_odd, [1, 2, 3, 4, 5, 6])

#过滤list中的空格
def not_empty(s):
    return s and s.strip()   #s过滤了'None'元素，s.strip()默认过滤空格
   
print "not_empty:", filter(not_empty, ['A', ' ', 'B', None, 'C', '  '])