columbus <- st_read(system.file("shapes/columbus.gpkg", package="spData")[1], quiet=TRUE)
col.gal.nb <- read.gal(system.file("weights/columbus.gal", package="spData")[1])
coords <- st_coordinates(st_centroid(columbus))
col.tri.nb <- tri2nb(coords)
oldpar <- par(mfrow=c(1,2))
if (require("dbscan", quietly=TRUE)) {
col.soi.nb <- graph2nb(soi.graph(col.tri.nb, coords))
plot(st_geometry(columbus), border="grey")
plot(col.soi.nb, coords, add=TRUE)
title(main="Sphere of Influence Graph", cex.main=0.7)
plot(st_geometry(columbus), border="grey")
plot(complement.nb(col.soi.nb), coords, add=TRUE)
title(main="Complement of Sphere of Influence Graph", cex.main=0.7)
}
par(mfrow=c(2,2))
col2 <- droplinks(col.gal.nb, 21)
plot(intersect.nb(col.gal.nb, col2), coords)
title(main="Intersect", cex.main=0.7)
plot(union.nb(col.gal.nb, col2), coords)
title(main="Union", cex.main=0.7)
plot(setdiff.nb(col.gal.nb, col2), coords)
title(main="Set diff", cex.main=0.7)
par(oldpar)
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