官网解释：

filter(function,iterable)

Construct a list from those elements ofiterablefor whichfunctionreturns true.iterablemay be either a sequence, a container which supports iteration, or an iterator. Ifiterableis a string or a tuple, the result also has that type; otherwise it is always a list. IffunctionisNone, the identity function is assumed, that is, all elements ofiterablethat are false are removed.

Note thatfilter(function,iterable)is equivalent to[itemforiteminiterableiffunction(item)]if function is notNoneand[itemforiteminiterableifitem]if function isNone.

Seeitertools.ifilter()anditertools.ifilterfalse()for iterator versions of this function, including a variation that filters for elements where thefunctionreturns false.



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 itsvalues 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', ' '])



补充：

.strip(None/string)：从头尾开始，按对象字符串顺序删除

a.如果strip参数中没有对象头尾开始的字符，则无法删除，返回对象全字符

str1='www.example.com'print(str1.strip('lcoz.'))####strip参数中没有'w'/'m'，两端删除受阻


b.如果strip参数中有对象的头尾开始字符，则匹配删除参数中的字符，返回未删除字符

str1='www.example.com'print(str1.strip('lcwmeoza.'))xamp####strip参数中没有'x'/'p',两端删除受阻