topology: Vector topology methods

In terra: Spatial Data Analysis

Vector topology methods

Description

makeNodes create nodes on lines

mergeLines connect lines to form polygons

removeDupNodes removes duplicate nodes in geometries and optionally rounds the coordinates

emptyGeoms returns the indices of empty (null) geometries. is.na also checks if any of the coordinates is NA.

snap makes boundaries of geometries identical if they are very close to each other. The tolerance is expressed in the coordinate reference system's units: meters (or feet, etc.) for projected data, and degrees for lon/lat data. To snap lon/lat geometries with a tolerance expressed in meters, project the data to a metric CRS first with project, snap, then project back. simplifyGeom uses the same convention.

Usage

## S4 method for signature 'SpatVector'
mergeLines(x)
## S4 method for signature 'SpatVector'
snap(x, y=NULL, tolerance)
## S4 method for signature 'SpatVector'
removeDupNodes(x, digits = -1)
## S4 method for signature 'SpatVector'
makeNodes(x)

Arguments

x	SpatVector of lines or polygons
y	SpatVector of lines or polygons to snap to. If NULL snapping is to the other geometries in x
tolerance	numeric. Snapping tolerance, expressed in the units of the CRS of x (i.e. meters or feet for projected data, degrees for lon/lat data). One degree of latitude is approximately 111 km.
digits	numeric. Number of digits used in rounding. Ignored if < 0

Value

SpatVector

See Also

sharedPaths, gaps, simplifyGeom, forceCCW, fillHoles

Examples

p1 <- as.polygons(ext(0,1,0,1))
p2 <- as.polygons(ext(1.1,2,0,1))

p <- rbind(p1, p2)

y <- snap(p, tol=.15)
plot(p, lwd=3, col="light gray")
lines(y, col="red", lwd=2)

terra documentation built on Aug. 22, 2026, 5:07 p.m.