cartography (version 2.4.2)

getBorders: Extract Polygons Borders

Description

Extract borders between polygons.

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

Usage

getBorders(x, id, spdf, spdfid = NULL)
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)

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)

res

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

width

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

Examples

# NOT RUN {
library(sf)
mtq <- st_read(system.file("gpkg/mtq.gpkg", package="cartography"))
# Get borders
mtq.borders <- getBorders(x = mtq)
# Plot polygons
plot(st_geometry(mtq), border = NA, col = "grey60")
# Plot borders
plot(st_geometry(mtq.borders), 
     col = sample(x = rainbow(nrow(mtq.borders))), 
     lwd = 3, add = TRUE)
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)
# }