我如何在python中将很长的字符串拆分为较短的字符串列表

>>> s = \"This is a very long string with many many many many and many more sentences and there is not one character that i can use to split by, just by number of words\"
>>> l = s.split()
>>> n = 5
>>> [\' \'.join(l[x:x+n]) for x in xrange(0, len(l), n)]
[\'This is a very long\',
 \'string with many many many\',
 \'many and many more sentences\',
 \'and there is not one\',
 \'character that i can use\',
 \'to split by, just by\',
 \'number of words\']

def split_chunks(s, chunksize):
    pos = 0
    while(pos != -1):
        new_pos = s.rfind(\" \", pos, pos+chunksize)
        if(new_pos == pos):
            new_pos += chunksize # force split in word
        yield s[pos:new_pos]
        pos = new_pos

>>> foo = \"asdf qwerty sderf sdefw regf\"
>>> list(split_chunks(foo, 6)
[\'asdf\', \' qwert\', \'y\', \' sderf\', \' sdefw\', \' regf\', \'\']

def split_n_chunks(s, words_per_chunk):
    s_list = s.split()
    pos = 0
    while pos < len(s_list):
        yield s_list[pos:pos+words_per_chunk]
        pos += words_per_chunk