Aggregate a spatial neighbours object
The method aggregates a spatial neighbours object, creating a new object listing the neighbours of the aggregates.
## S3 method for class 'nb' aggregate(x, IDs, remove.self = TRUE, ...)
x |
an nb neighbour object |
IDs |
a character vector of IDs grouping the members of the neighbour object |
remove.self |
default TRUE: remove self-neighbours resulting from aggregation |
... |
unused - arguments passed through |
an nb neighbour object, with empty aggregates dropped.
Method suggested by Roberto Patuelli
Roger Bivand Roger.Bivand@nhh.no
data(used.cars, package="spData") data(state) cont_st <- match(attr(usa48.nb, "region.id"), state.abb) cents <- as.matrix(as.data.frame(state.center))[cont_st,] opar <- par(mfrow=c(2,1)) plot(usa48.nb, cents, xlim=c(-125, -65), ylim=c(25, 50)) IDs <- as.character(state.division[cont_st]) agg_cents <- aggregate(cents, list(IDs), mean) agg_nb <- aggregate(usa48.nb, IDs) plot(agg_nb, agg_cents[, 2:3], xlim=c(-125, -65), ylim=c(25, 50)) text(agg_cents[, 2:3], agg_cents[, 1], cex=0.6) par(opar)
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