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From Ajo Fod <ajo....@gmail.com>
Subject Re: [math] enumerating combinations
Date Tue, 20 Aug 2013 19:34:05 GMT
I feel like it belongs in a separate class in utils.

-Ajo


On Tue, Aug 20, 2013 at 12:24 PM, Phil Steitz <phil.steitz@gmail.com> wrote:

> On 8/20/13 12:09 PM, Ajo Fod wrote:
> > I think it belongs in stat.inference. That is where all the tests are.
>
> Sorry, I should have been more clear.  I intend to put
> KolmogorovSmirnovTest in stat.inference.  I agree it belongs there.
> What I am puzzling over is where to put the combinations iterator.
>
> Phil
> >
> > -Ajo
> >
> >
> > On Tue, Aug 20, 2013 at 8:51 AM, Phil Steitz <phil.steitz@gmail.com>
> wrote:
> >
> >> The monte carlo approach I developed for 2-sample Kolmogorov-Smirnov
> >> tests converges too slowly to be practical.  I suspect full
> >> enumeration of n - m partitions of n + m will actually be faster for
> >> small m + n.  To do this, I need to enumerate combinations.  I have
> >> implemented a fast, non-recursive algorithm to do this (Knuth's
> >> algorithm T from 7.2.1.3 of TACP 4A), exposed as
> >>
> >> class LexicographicCombinationIterator implements Iterator<int[]>
> >>
> >> The constructor takes <n, k> and the int[] arrays returned by next()
> >> are increasing k-length arrays from {0, ..., n - 1}, iterated in
> >> lexicographic order.  The array-based approach is what I need in K-S
> >> and also fastest.
> >>
> >> Initially, I implemented this as a private inner class in
> >> KolmogorovSmirnovTest, but this is making testing inconvenient and
> >> it also seems like a generically useful class.  The question is
> >> where to put it.  One possibility is to make it a public inner class
> >> of MathArrays.  Of just add it as a class in util.  Advice appreciated.
> >>
> >> Phil
> >>
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> >>
>
>
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