DESCRIPTION

Import and generation of patch raster data based on individual patch based raster data.

NOTES

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EXAMPLE

An example for the North Carolina sample dataset: In order to run r.pi.import we need an exported patch index raster: 
r.pi.index input=landclass96 output=landclass96_forestclass5_area keyval=5 method=area
export this resulting map: 
r.pi.export input=landclass96_forestclass5_area output=patch_area_out values=patch_area_values id_raster=forestclass5_ID stats=average,variance,min
modify it with R or just import the file again and assign the percentage coverage to each fragment. You need the patch_area_values file and the previously used input file forestclass96 raster (important: the same patch coverage is mandatory otherwise patch ID in the text file and raster are not congruent!): 
r.pi.import input=patch_area_values raster=landclass96 output=imported_values keyval=5 id_col=1 val_col=2
if you want to export the patch values to R and do e.g. a linear regression of two patch values and import them again in GRASS, do:
apply r.pi.export with two indices (A and B), in R, do: 
resid.AB <- resid(lm(A[,3]~B[,3])) #write residuals of a linear regression
df.resid.AB <- data.frame(A[,1],resid.AB) #merge patch IDs and resid into same data frame
write.table(df.resid.AB,"resid.for.GRASS",row.names=F,col.names=F)
exit R and run in GRASS: 
r.pi.import input=resid.for.GRASS raster=landclass96 output=resid.AB keyval=5 id_col=1 val_col=2

SEE ALSO

r.pi.export, r.pi

AUTHORS

Programming: Elshad Shirinov
Scientific concept: Dr. Martin Wegmann
Department of Remote Sensing
Remote Sensing and Biodiversity Unit
University of Wuerzburg, Germany

Port to GRASS GIS 7: Markus Metz

Last changed: $Date$