```
library(raster)
# Make random forest cover map
emptyRas <- raster(extent(0,1e2,0,1e2), res = 1)
# start from two cells near middle
loci <- (ncell(emptyRas)/2 - ncol(emptyRas))/2 + c(-3, 3)
# Allow overlap
emptyRas[] <- 0
Rings <- rings(emptyRas, loci = loci, allowOverlap = TRUE, returnIndices = TRUE)
# Make a raster that adds together all id in a cell
wOverlap <- Rings[,list(sumEventID=sum(id)),by="indices"]
emptyRas[wOverlap$indices] <- wOverlap$sumEventID
if (interactive())
Plot(emptyRas, new = TRUE)
# No overlap is default, occurs randomly
emptyRas[] <- 0
Rings <- rings(emptyRas, loci = loci, minRadius = 7, maxRadius = 9, returnIndices = TRUE)
emptyRas[Rings$indices] <- Rings$id
if (interactive())
Plot(emptyRas, new = TRUE)
# Variable ring widths, including centre cell for smaller one
emptyRas[] <- 0
Rings <- rings(emptyRas, loci = loci, minRadius = c(0,7), maxRadius = c(8, 18),
returnIndices = TRUE)
emptyRas[Rings$indices] <- Rings$id
if (interactive())
Plot(emptyRas, new = TRUE)
```

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