itertools.groupby

[Carsten Haese]

On Sun, 2007-05-27 at 20:28 -0700, Paul Rubin wrote:
>    fst = operator.itemgetter(0)
>    snd = operator.itemgetter(1)
> 
>    def bates(fd):
>      # generate tuples (n,d) of lines from file fd,
>      # where n is the record number.  Just iterate through all lines
>      # of the file, stamping a number on each one as it goes by.
>      n = 0   # record number
>      for d in fd:
>         if d.startswith('New Record'): n += 1
>         yield (n, d)
> 
>    def records(fd):
>       for i,d in groupby(bates(fd), fst):
>          yield imap(snd, d)

Now there's a clever variation of the Schwartzian transform: decorate,
groupby, undecorate.

That's a nice example of groupby, but it could benefit from using better
variable names.

-- 
Carsten Haese
http://informixdb.sourceforge.net