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Date: Sun, 26 Sep 2010 23:19:23 +0200
From: Gilles Sadowski <gilles@harfang.homelinux.org>
To: dev@commons.apache.org
Subject: Re: [math] speeding up percentile based statistics
Message-ID: <20100926211923.GN10200@dusk.harfang.homelinux.org>
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> [...]
> >>
> >> ---CUT---
> >>    double[] a = new double[] {1, 2, 3};
> >>    double[] b = new double[] {1, 2, 3, 4, 5};
> >>    Percentile pA = new Percentile(a);
> >>    Percentile pB = new Percentile(b);
> >>
> >>    double r;
> >>    r = pA.evaluate(50);
> >>    r = pB.evaluate(50);
> >>    r = pA.evaluate(50);
> >>    r = pB.evaluate(50);
> >> ---CUT---
> >>
> >> That way, later calls can benefit from whatever preprocessing was done in
> >> previous calls.
> >> The instance will always control all the information needed (e.g. after a
> >> call to an "addValues" method) for the processing without the need to rely
> >> on the user for calling "clearCache" whenever necessary.
> >>
> >>
> >> Gilles
> > 
> > +1
> > I think that is a really good idea and I agree on the points made.
> 
> This proposal is point 4. It breaks the UnivariateStatistic API and it
> breaks what the user found interesting in this API, i.e. have a general
> statistics framework where one statistic can be replaced by another one.
> 
> If you read again one of my earlier messages from today, we will combine
> this method (i.e. evaluate without values) and the UnivariateStatistics API.
> 
> Perhaps we could add these new methods (i.e. addValues and evaluate
> without values) to UnivariateStatistics, but this can only be done on 3.0.

+1

Is it urgent to complicate the code? If the API conflicts with a necessary
efficiency improvement, why not postpone the change?


Gilles

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