[GRASS-user] mantel correlogram

[Thomas Adams]

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 <tech_dev at wildintellect.com> 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
> > _______________________________________________
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> > grass-user at lists.osgeo.org <javascript:;>
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
>
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-- 
Thomas E Adams, III
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