[Python-ideas] Yet another sum function (fractions.sum)

[David Mertz]

On Tue, Aug 20, 2013 at 3:26 PM, Oscar Benjamin
<oscar.j.benjamin at gmail.com>wrote:

> So with all our powers combined I created binsortmergesum (bsms) and
> it looks like this:
>
> def bsms(iterable):
>     bins = defaultdict(int)
>     for num in iterable:
>         bins[num.denominator] += num.numerator
>     return mergesum([F(n, d) for d, n in sorted(bins.items())])
>

Wow.  I noticed that you didn't do a sort in your binsum(), but I didn't
think it would make much difference.  Actually, I thought the cost of the
sort wouldn't be worth it at all.  It's actually a little unclear to me
exactly why it makes such a big difference as it does in the 'e' case.

Still, I love that function.  It's simple, elegant, and fast (when used on
Fraction, of course; not everywhere).


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