cartography (version 2.2.1)

getOuterBorders: Extract Polygons Outer Borders

Description

Extract outer borders between polygons. Outer borders are non-contiguous polygons borders (e.g. maritime borders).

Usage

getOuterBorders(x, id, res = NULL, width = NULL, spdf, spdfid = NULL)

Arguments

x

an sf object, a simple feature collection or a SpatialPolygonsDataFrame.

id

name of the identifier variable in x, default to the first column. (optional)

res

resolution of the grid used to compute borders (in x units). A high resolution will give more detailed borders. (optional)

width

maximum distance between used to compute borders (in x units). A higher width will build borders between units that are farther apart. (optional)

spdf

deprecated, a SpatialPolygonsDataFrame. This SpatialPolygonsDataFrame has to be projected (planar coordinates).

spdfid

deprecated, identifier field in spdf, default to the first column of the spdf data frame. (optional)

Value

An sf object (MULTILINESTRING) of borders is returned. This object has three id variables: id, id1 and id2. id1 and id2 are ids of units that neighbour a border; id is the concatenation of id1 and id2 (with "_" as separator).

See Also

discLayer, getBorders

Examples

# NOT RUN {
library(sf)
mtq <- st_read(system.file("gpkg/mtq.gpkg", package="cartography"))
# Get units borders
mtq.outer <- getOuterBorders(x = mtq, res = 1000, width = 2500)
# Plot municipalities
plot(st_geometry(mtq), col = "grey60")
# Plot borders
plot(st_geometry(mtq.outer), col = sample(x = rainbow(nrow(mtq.outer))),
     lwd = 3, add = TRUE)
# }