split():

当函数默认为空,它会把所有空格(空格符、制表符、换行符)当作分隔符.

但是当函数参数默认为其他,将会对 空格符、制表符、换行符 当作元素进行分割.

a = 'hello world!'

print a.split()

a = 'hello world!' \

    ''

print a.split()

a = 'hello world! ' \

    ''

print a.split(' ')

相对应的输出结果

['hello', 'world!']

['hello', 'world!']

['hello', 'world!', '']

第三个a中的换行符，被当作新元素进行了分割.

print a.split(' ')

print filter(None, a.split(' '))

输出结果为:

['hello', 'world!']

filter(...)
filter(function or None, sequence) -> list, tuple, or string

Return those items of sequence for which function(item) is true. If
function is None, return the items that are true. If sequence is a tuple
or string, return the same type, else return a list.

注意绿字部分:

感谢博主.SZlibraco

原链接:

http://www.cnblogs.com/librasz/p/3232611.html