On May 29, 2:34 am, Raymond Hettinger <[EMAIL PROTECTED]> wrote:
> If the posters on this thread have developed an interest
> in the subject, I would find it useful to hear their
> ideas on new and creative ways to use groupby(). The
> analogy to UNIX's uniq filter was found only after the
> design was complete. Likewise, the page numbering trick
> (shown above by Paul and in the examples in the docs)
> was found afterwards. I have a sense that there are entire
> classes of undiscovered use cases which would emerge
> if serious creative effort where focused on new and
> interesting key= functions (the page numbering trick
> ought to serve as inspiration in this regard).
>
> The gauntlet has been thrown down. Any creative thinkers
> up to the challenge? Give me cool recipes.
Although obfuscated one-liners don't have a large coolness factor in
Python, I'll bite:
from itertools import groupby
from random import randint
x = [randint(0,100) for _ in xrange(20)]
print x
n = 7
# <-- insert fat comments here about the next line --> #
reduce(lambda acc,(rem,divs): acc[rem].extend(divs) or acc,
groupby(x, key=lambda div: div%n),
[[] for _ in xrange(n)])
George
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