Alex, I believe Tyler does plan on using R for the statistical analyses, but using GRASS GIS in combination with R is the easiest path, I think.
Tom On Tuesday, March 11, 2014, Alex Mandel <[email protected]> wrote: > Use R. It includes Moran's I and Geary's C tests for > spatial-autocorrelation. Look like it has mantel too. > > You'll probably need the sp, spdep and rgdal packages. You might also > want to use the Raster package to extract the sampling data, or you can > use spGRASS to tie the R and Grass together. > > See chapter 9 (1st ed) of Applied Spatial Data Analysis with R. > http://www.asdar-book.org/ > > Enjoy, > Alex > > On 03/11/2014 09:18 AM, Tyler Smith wrote: > > Hello, > > > > We're preparing a field sampling program, and would like to determine > > a minimum distance between samples to reduce/eliminate spatial > > autocorrelation. I think a good approach would be to calculate a > > mantel correlogram, and use the range of the correlogram as our > > minimum sampling distance. > > > > * Questions > > > > 1) is this a reasonable approach > > 2) if so, how best to do this? > > > > * Details > > We have a vector map with the point coordinates of several hundred > > potential sampling sites, and ~ 10 raster layers with appropriate data > > to test for spatial autocorrelation (WORLDCLIM, soils). I could do > > something like the following, but I'm not sure if there's a simpler or > > more appropriate approach: > > > > 1) extract the raster data for each point > > 2) save the data to csv; import into R > > 3) calculate the spatial distances between points, after projecting > > the lat-long data into an appropriate scale (?) > > 4) calculate the climate distance using the WORLDCLIM data > > 5) use the 'mgram' function in the 'ecodist' package to calculate the > > actual correlogram between the spatial distance and climate distance > > > > Any suggestions on the approach or the methods would be welcome! > > > > Thanks, > > > > Tyler > > _______________________________________________ > > grass-user mailing list > > [email protected] <javascript:;> > > http://lists.osgeo.org/mailman/listinfo/grass-user > > > > _______________________________________________ > grass-user mailing list > [email protected] <javascript:;> > http://lists.osgeo.org/mailman/listinfo/grass-user > -- Thomas E Adams, III 718 McBurney Drive Lebanon, OH 45036 1 (513) 739-9512 (cell)
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