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filter(function, iterable)
Construct a list from those elements of iterable for which function returns true. iterable may be either a sequence, a container which supports iteration, or an iterator. If iterable is a string or a tuple, the result also has that type; otherwise it is always a list. If function is None, the identity function is assumed, that is, all elements of iterable that are false are removed.
Note that filter(function, iterable) is equivalent to [item for item in iterable if function(item)] if function is not None and [item for itemin iterable if item] if function is None.
See itertools.ifilter() and itertools.ifilterfalse() for iterator versions of this function, including a variation that filters for elements where the function returns 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 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])
.jpg)
#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', ' '])
.jpg)
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