question

[Peter Otten]

 CarpeSkium at gmail.com wrote:

> "I've parsed a webpage into a text file. In doing so, I've kept all
> the text I'm interested in, and removed all the text I don't want. My
> result is a text file that is comma-separated. However, the text file
> is one, very long, single string. I need to substitute every eighth
> (8th) comma with a new line ("\n"). I've tried regular expressions,
> but don't know how to make this happen on only every eighth comma. I'd
> post my code, but none of it works. Thanks for the help."

>>> text = "aaa," * 20
>>> from itertools import cycle, groupby
>>> print "\n".join(",".join(g) for k, g in groupby(text.split(","),
...     key=lambda key, c=cycle([True]*8+[False]*8): c.next()))
aaa,aaa,aaa,aaa,aaa,aaa,aaa,aaa
aaa,aaa,aaa,aaa,aaa,aaa,aaa,aaa
aaa,aaa,aaa,aaa,

:-)

Peter