[R-sig-Geo] Assign a unique ID number to each patch in a raster

[Nelly Reduan]

Hello,
I would like to assign a unique ID number to each patch (a patch is composed of a set of adjacent cells) as shown in this figure:
 [cid:bab831e5-4246-4a77-884c-0012101662a5]

I tested the clump function (package raster) by applying an eight adjacent cells rule but this function mixes all cell values into single patch.

Here is a code example to create a raster. The raster contains values ranged from 1 to 9.
r <- raster(ncols=12, nrows=12)
r[] <- round(runif(ncell(r),1,9),digits=0)
plot(r)

Is there a way to assign a unique ID number to grouping cells that form a patch for each class (i.e., values 1, 2, 3, 4, 5, 6, 7, 8, 9) ?

Thanks a lot for your time
Nell


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