Re: [R] about"Riply's K function"and "envelope"

From: Roger Bivand <Roger.Bivand_at_nhh.no>
Date: Tue 28 Feb 2006 - 08:16:23 EST


On Mon, 27 Feb 2006, zhang jian wrote:

> I have tried the package"spatial" and "splance".But it is not good.

You are not correct. All three packages, spatial, splancs, and spatstat can be used, and, for the same bounding window, will give the same results. Your complain that spatstat has difficulties computing simulation envelopes for 2000 points (in your fourth appeal for help) also seems unlikely. My impression is that you are not following advice given, and are trying to simulate with an unnecessarily large number of replications, and very likely for far too many distance bins.

Please simplify your task to something that you can make work. In each of the three packages, calculating khat and computing simulation envelopes is just a couple of lines, so try to get them right on a small data set that you understand. Following the examples in the package will be a good start.

Once you have made it work on a small subset of your data following the examples in the packages, you can scale up to your full data sets.

> I think there are some questions when I run the programs.
> I attach a part of data. can you help me try to do it? And attach a simple
> program to me.
> my plot is square, 500m*500m.
> > PIKO[1:10,]
> code species dbh x y tag status branch
> 92 10142 PIKO 38.9 6.05 12.81 10165 alive 0
> 109 10213 PIKO 41.0 6.71 26.21 10202 alive 0
> 135 10222 PIKO 48.3 18.98 21.28 10214 alive 0
> 146 10223 PIKO 47.0 19.45 22.83 10224 alive 0
> 147 10223 PIKO 20.0 19.74 28.65 10225 alive 0
> 151 10223 PIKO 23.3 17.03 28.88 10229 alive 0
> 152 10223 PIKO 33.5 16.94 27.25 10230 alive 0
> 176 10232 PIKO 43.5 19.20 30.88 10248 alive 0
> 181 10233 PIKO 39.0 18.10 35.60 10252 alive 0
> 212 10243 PIKO 71.2 6.94 37.27 10281 alive 0
>
> "x,y" are coordinations. I want to use them to do Ripley's K analysis.
> thank you very much!
> Help me!
> jian zhang
>
> On 2/27/06, Sundar Dorai-Raj <sundar.dorai-raj@pdf.com> wrote:
> >
> >
> >
> > zhang jian wrote:
> > > hi!
> > > I did Riply's K function and envelope in the package "SPATSTAT". When
> > the
> > > species number is less, it can work well and it is quickly. But when the
> > > species number is more(example:2000), it told me"memory limit". So I
> > change
> > > "memory limit". But the speed is very slow. I took 13 hours to run the
> > > programe.
> > > Perhaps there are other methods that can do it. Or just change some
> > > parsmeters.
> > > who can help me?
> > > Thank you!
> > > Jian
> > Zhang
> > >
> >
> > I don't have an example, but have you looked at ?Kenvl in the spatial
> > package?
> >
> > HTH,
> >
> > --sundar
> >
>
> [[alternative HTML version deleted]]
>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand@nhh.no

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Received on Tue Feb 28 08:25:01 2006

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