erase function

Erase parts of a SpatVector object

Erase parts of a SpatVector with another SpatVector or with a SpatExtent. You can also erase (parts of) polygons with the other polygons of the same SpatVector. methods

## S4 method for signature 'SpatVector,SpatVector'
erase(x, y)

## S4 method for signature 'SpatVector,missing'
erase(x, sequential=TRUE)

## S4 method for signature 'SpatVector,SpatExtent'
erase(x, y)

Arguments

• x: SpatVector
• y: SpatVector or SpatExtent
• sequential: logical. Should areas be erased sequentially? See Details

Returns

SpatVector or SpatExtent

See Also

crop and intersect for the inverse.

The equivalent for SpatRaster is mask

Details

If polygons are erased sequentially, everything that is covered by the first polygon is removed from all other polygons, then everything that is covered by (what is remaining of) the second polygon is removed, etc.

If polygons are not erased sequentially, all overlapping areas are erased and only the areas covered by a single geometry are returned.

Examples

f <- system.file("ex/lux.shp", package="terra")
v <- vect(f)

# polygons with polygons or extent

e <- ext(5.6, 6, 49.55, 49.7)
x <- erase(v, e)

p <- vect("POLYGON ((5.8 49.8, 6 49.9, 6.15 49.8, 6 49.6, 5.8 49.8))")
y <- erase(v, p)

# lines with polygons
lns <- as.lines(rast(v, ncol=10, nrow=10))[12:22]
eln <- erase(lns, v)
plot(v)
lines(lns, col='blue', lwd=4, lty=3)
lines(eln, col='red', lwd=2)

## self-erase
h <- convHull(v[-12], "NAME_1")
he <- erase(h)
plot(h, lwd=2, border="red", lty=2)
lines(he, col="gray", lwd=3)