Thank you Roger, I've posted the original shape file for the dataset on the website at: http://web.ics.purdue.edu/~twgriffi/R_matrix.htm
One shape file is projected while the other is not; however both sets of *.dbf are identical and contain both decimal degrees and Northing and Easting in meters. I chose a <=75 meter distance threshold and a power=1. The final inverse distance matrix was row standardized so it is not symmetric. The weight characteristics you list below are nearly identical to those that SpaceStat provides. I really appreciate this. Thank you, Terry -----Original Message----- From: Roger Bivand [mailto:[EMAIL PROTECTED] Sent: Friday, March 17, 2006 5:50 PM To: Griffin, Terry W Cc: [email protected] Subject: RE: [R-sig-Geo] inverse distance weights matrix Terry: http://web.ics.purdue.edu/~twgriffi/mat4rf and http://web.ics.purdue.edu/~twgriffi/mat4rs throw access errors. Do you have the coordinates and your specifications for the inverse weighted neighbours (distance threshold, power if any)? inMAT <- matrix(scan("cottonID75wm", sep=","), nrow=2451, ncol=2451, byrow=TRUE) does read the matrix - the weights aren't symmetric, are they? >From the weights matrix I get: inMATlw <- mat2listw(inMAT) print(is.symmetric.nb(inMATlw$neighbours)) [1] TRUE print(inMATlw$neighbours) Neighbour list object: Number of regions: 2451 Number of nonzero links: 1182982 Percentage nonzero weights: 19.69208 Average number of links: 482.6528 If you could post the coordinates and your specifications, I could see how to reproduce the weights within R if you like. Roger On Fri, 17 Mar 2006, Griffin, Terry W wrote: > > The MATLAB routines are the Spatial Econometrics Toolbox format. I > tried the read.dat2listw() in R; the code and error message for a small > matrix example is below; this uses a full matrix from MATLAB (realizing > that "read.dat2listw" is intended for sparse matrices). > > > mattry<-read.dat2listw("mat4rf") > Error in "[.default"(sn, , 1) : incorrect number of dimensions > > traceback() > 5: NextMethod("[") > 4: "[.factor"(sn, , 1) > 3: sn[, 1] > 2: unique(sn[, 1]) > 1: read.dat2listw("mat4rf") > > > I'm not able to use dlmwrite in MATLAB to export the sparse matrix so I > tried to import the full matrix into R (code is above). The MATLAB code > I'm using came from this listserve archive. The MATLAB code and error > message are below. I'm able to use dlmwrite to create the MATLAB full > matrix (used above in the R code). > > load testmat.GWT; A = (spconvert(testmat)); %have to change name in two > locations on this line > n=size(A); nobs=n(1); > % Normalize matrix (adapted form LeSage 1999) > wt = sparse(A); > [i1,j1,s1]=find(wt); > rsum=sum(wt); > for i=1:nobs; > ind=find(i1==i); > s1(ind,1)=s1(ind,1)/rsum(1,i); > end; > [m,n] = size(wt); > W = sparse(i1,j1,s1,m,n); > S = sparse(W); > dlmwrite('mat4rst', S); %give the new sparse weight matrix a permanent > name for R > ??? Error using ==> sprintf > Function is not defined for sparse inputs. > > Error in ==> dlmwrite at 172 > str = sprintf(format,m(i,:)); > > If anyone wants to give it a try, I've put the small example matrices > and the "real" matrix up on my website at: > http://web.ics.purdue.edu/~twgriffi/R_matrix.htm > > My objective is to use R for my spatial data analysis using inverse > distance weights matrices. I'm struggling with the inverse distance > matrices. I hope to either create these inverse distance matrices in > SpaceStat then import into R or create the matrices in R. > > Thank you, > > Terry > > > > > -----Original Message----- > From: Roger Bivand [mailto:[EMAIL PROTECTED] > Sent: Friday, March 17, 2006 2:43 PM > To: Griffin, Terry W > Cc: [email protected] > Subject: Re: [R-sig-Geo] inverse distance weights matrix > > On Thu, 16 Mar 2006, Griffin, Terry W wrote: > > > Greetings, > > > > > > > > I'm migrating from MATLAB to R and am having trouble converting > inverse > > distance weights matrix into a form usable by R. I've created the > > matrix in SpaceStat (in *.FMT format) and converted to *.GWT format > and > > also have it in MATLAB *.m format. > > > > I wonder whether your Matlab data are in the Spatial Econometrics > Toolbox > format - if they are, you could try the read.dat2listw() function > mentioned on the read.gwt2nb function help page. > > > > > > I've tried using the read.gwt2nb in R, but without success. There are > > nearly 2,451 observations with an average of 482 linkages. About 20 % > > have nonzero weights. Any suggestions are appreciated. > > Without details of what you mean by "without success", it's hard to > offer > any advice. Could you create a small example of the problems you are > seeing, and repost with copies of the commands you give and any error > messages? > > If you are seeing errors ("Error in ..." messages from R), please also > type traceback() at the prompt and report the output. You could also put > the uncooperative GWT file on a website for others to try to see what is > going on. > > > > > > > > > Thank you, > > > > Terry > > > > > > > > > > > > Terry W. Griffin > > > > Graduate Research Assistant > > > > Agricultural Economics > > > > Purdue University > > > > 403 W State St > > > > West Lafayette, IN 47907 > > > > 765-494-4257 > > > > http://web.ics.purdue.edu/~twgriffi/ > > <http://web.ics.purdue.edu/~twgriffi/> > > > > > > > > > > > > > > [[alternative HTML version deleted]] > > > > _______________________________________________ > > R-sig-Geo mailing list > > [email protected] > > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > > > > -- 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: [EMAIL PROTECTED] _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
