subset.nb: Subset a neighbours list

Description Usage Arguments Value Author(s) See Also Examples

View source: R/subset.nb.R

Description

The function subsets a neighbors list, retaining objects for which the subset argument vector is TRUE.

Usage

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## S3 method for class 'nb'
subset(x, subset, ...)

Arguments

x

an object of class nb

subset

logical expression

...

generic function pass-through

Value

The function returns an object of class nb with a list of integer vectors containing neighbour region number ids (compacted to run from 1:number of regions in subset).

Author(s)

Roger Bivand [email protected]

See Also

nb2listw

Examples

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example(columbus)
coords <- coordinates(columbus)
plot(col.gal.nb, coords)
to.be.dropped <- c(31, 34, 36, 39, 42, 46)
text(coords[to.be.dropped,1], coords[to.be.dropped,2], labels=to.be.dropped,
  pos=2, offset=0.3)
sub.col.gal.nb <- subset(col.gal.nb,
  !(1:length(col.gal.nb) %in% to.be.dropped))
plot(sub.col.gal.nb, coords[-to.be.dropped,], col="red", add=TRUE)
which(!(attr(col.gal.nb, "region.id") %in%
  attr(sub.col.gal.nb, "region.id")))

Example output

Loading required package: sp
Loading required package: Matrix

colmbs> require(maptools)
Loading required package: maptools
Checking rgeos availability: TRUE

colmbs> columbus <- readShapePoly(system.file("etc/shapes/columbus.shp",
colmbs+  package="spdep")[1])

colmbs> col.gal.nb <- read.gal(system.file("etc/weights/columbus.gal",
colmbs+  package="spdep")[1])
Warning message:
use rgdal::readOGR or sf::st_read 
[1] 31 34 36 39 42 46

spdep documentation built on Sept. 2, 2017, 1:11 a.m.