Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!gegeweb.42!gegeweb.eu!nntpfeed.proxad.net!proxad.net!feeder2-2.proxad.net!nx01.iad01.newshosting.com!newshosting.com!69.16.185.16.MISMATCH!npeer02.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!spln!extra.newsguy.com!newsp.newsguy.com!news7
From: Wojtek <nowhere@a.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: RandomDirichlet?
Date: Tue, 01 Nov 2011 04:54:36 -0700
Organization: NewsGuy - Unlimited Usenet $19.95
Lines: 29
Message-ID: <mn.09267dbb94fe8ed2.70216@a.com>
References: <CAD575DC.8551%bravegag@hotmail.com>
NNTP-Posting-Host: p96c9af138f0eac2ea5fa47c39d56f968467f735967f0e78f.newsdawg.com
Mime-Version: 1.0
Content-Type: text/plain; charset="iso-8859-15"; format=flowed
Content-Transfer-Encoding: 8bit
X-Newsreader: MesNews/1.08.03.00-gb
Xref: x330-a1.tempe.blueboxinc.net comp.lang.java.programmer:9334

Giovanni Azua wrote :
> Hello,
>
> I need to generate random TPCH workloads but I don't want a Uniform
> distribution where Q1, RF1, RF2 would be equally probable i.e. using new
> Random().nextInt(..)
>
> I instead would like to draw samples from a Dirichlet distribution which
> would give a very skewed PD depending on the input alphas (which specify how
> skewed I want the PD to be). The Matlab code would be exactly:
>
> function r = dirichlet_sample(a,n)
> p = length(a);
> r = gamrnd(repmat(a,n,1),1,n,p);
> r = r ./ repmat(sum(r,2),1,p);
> End
>
> But there is no "gamrnd" RandomGamma in Java nor RandomDirichlet. Before I
> spend time writing this, can anyone advice for a low-footprint library
> implementing those functions?

Google is your friend: java RandomDirichlet

jgibblda.sourceforge.net

-- 
Wojtek :-)