Some articles: >From fields to objects: A review of geographic boundary analysis http://www.springerlink.com/content/q1kxcfqegmrmjv92/
Integrating Edge Detection and Dynamic Modeling in Quantitative Analyses of Ecological Boundaries http://www.bioone.org/perlserv/?request=get-abstract&issn=0006-3568&volume=053&issue=08&page=0730 Measuring the abruptness of patchy ecotones - A simulation-based comparison of landscape pattern statistics http://www.springerlink.com/content/k556v88m62g02462/ Edge effects in fragmented landscapes: a generic model for delineating area of edge influences (D-AEI) http://scholar.google.com/url?sa=U&q=http://research.eeescience.utoledo.edu/lees/pubs/zheng2000.pdf I've got a lot more in my endnote database, I can send you the file if you want to because this copy pasting isn't exactly efficient. regards, Koen -- Koen Hufkens, Phds Department of Biology Research Group of Plant and Vegetation Ecology University of Antwerp Universiteitsplein 1 B-2610 Wilrijk, Belgium [EMAIL PROTECTED] > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Nicholas Lewin-Koh > Sent: zondag 12 november 2006 4:23 > To: Carlos A. Bastos M.Guerra > Cc: r-sig-geo@stat.math.ethz.ch > Subject: Re: [R-sig-Geo] how to do a principle component > analysis with geo-referenced points > > Hi Carlos, > I think that there are tools in the sp package for dealing with grids. > If I am understanding you correctly and you want to do > "zoning" of your region than you probably are not looking to > do pca, but some sort of clustering. > Marie Jose Fortin had some nice papers on a technique called > wombling, for finding regions of abrupt ecological change. > There are some other techniques for spatial partitioning, but > I am not sure if they are implemented in R. It has been a > long time since I worked on ecological problems. > > For more information on the spatial tools in R a good place > to start is http://cran.r-project.org/src/contrib/Views/Spatial.html > the CRAN task view for spatial statistics, and > http://cran.r-project.org/src/contrib/Views/Environmetrics.html > has some more pointers. > > Hope this helps, > > Nicholas > On Sat, 11 Nov 2006 20:24:59 -0000, "Carlos A. Bastos M.Guerra" > <[EMAIL PROTECTED]> said: > > > > Dear Nicholas, > > > > First of all thanks for the references, I think they will > help me with > > my current problem. :) The thing is that I am used to work > with AcrGIS > > to do the spatial analysis, but the statistical methods in > ArcGIS are > > a bit "dummy", namely in spatial PCA. I am used to work with R with > > the ade4 package :) but when I heard that I could do > spatial analysis > > with R I ad to try it...but its more difficult that it seams (at > > first)... > > > > What I did was: (in ArcGIS) convert the centroids of a grid into a > > point shape file, than I have integrated all the information into > > different columns. I converted the dbf file into a txt an then I > > imported the file into R ... and my problems began... :) > > > > My objective is to do a PCA and extract the different > groups of points > > in order to make an ecological zoning. > > > > I am still starting with R and "the Geo tools" can you > point me some > > reading material that I can use? > > > > Best regards, > > > > Carlos > > > > > > -----Mensagem original----- > > De: Nicholas Lewin-Koh [mailto:[EMAIL PROTECTED] > > Enviada: sábado, 11 de Novembro de 2006 19:06 > > Para: r-sig-geo@stat.math.ethz.ch > > Cc: Carlos GUERRA > > Assunto: [R-sig-Geo] RE: how to do a principle component > analysis with > > geo-referenced points > > > > Hi Carlos, > > There are a couple of ways to do this, but you have to be a little > > more specific about what your goals/intentions are. I > assume you have > > points p(x1,y1), ...., p(xn,yn), where p is a vector of > observations. > > > > If the goal is interpolation than you have to model the spatial > > covariance of the orthognal factors, and you should look at > > waekernagel's book. > > if your goal is to extract principal components and account for the > > variance induced by a spatial process, a quick and dirty > approach is > > to include polynomials of the xy coordinates in the data > and do pca on > > the augmented matrix. Take a look at > > > > Borcard, D., P. Legendre & P. Drapeau. 1992. Partialling out the > > spatial component of ecological variation. Ecology 73: 1045-1055 > > > > Méot, A., P. Legendre & D. Borcard. 1998. Partialling out > the spatial > > component of ecological variation: questions and > propositions in the > > linear modeling framework. Environmental and Ecological Statistics 5 > > (1): 1-27. > > > > Another approach is spatial factor analysis > > > > Christensen, WF, and Amemiya, Y (2001). "Generalized > shifted-factor > > analysis method for multivariate geo-referenced data," Mathematical > > Geology, 33, 801-824. > > > > Christensen, WF, and Amemiya, Y (2002). "Latent variable > analysis of > > multivariate spatial data," Journal of the American Statistical > > Association, 97, 302-317 > > > > If your question is there R code to do this, I think the > ade4 package > > can to the spatial variance partitioning, but for factor > analysis, you > > are on your own. > > > > Nicholas > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo