union: Union SpatVector or SpatExtent objects

In terra: Spatial Data Analysis

Union SpatVector or SpatExtent objects

Description

If you want to append polygon SpatVectors use rbind instead of union. union will also intersect overlapping polygons between, not within, objects. Union for lines and points simply combines the two data sets; without any geometric intersections. This is equivalent to rbind. Attributes are joined.

If x and y have a different geometry type, a SpatVectorCollection is returned.

If a single SpatVector is supplied, overlapping polygons are intersected. Original attributes are lost. New attributes allow for determining how many, and which, polygons overlapped.

SpatExtent: Objects are combined into their union; this is equivalent to +.

Usage

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

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

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

Arguments

x	SpatVector or SpatExtent
y	Same as x or missing

Value

SpatVector or SpatExtent

See Also

rbind

intersect

combineGeoms

merge and mosaic to union SpatRasters.

crop and extend for the union of SpatRaster and SpatExtent.

merge for merging a data.frame with attributes of a SpatVector.

aggregate to dissolve SpatVector objects.

Examples

e1 <- ext(-10, 10, -20, 20)
e2 <- ext(0, 20, -40, 5)
union(e1, e2)

#SpatVector
v <- vect(system.file("ex/lux.shp", package="terra"))
v <- v[,3:4]
p <- vect(c("POLYGON ((5.8 49.8, 6 49.9, 6.15 49.8, 6 49.65, 5.8 49.8))", 
"POLYGON ((6.3 49.9, 6.2 49.7, 6.3 49.6, 6.5 49.8, 6.3 49.9))"), crs=crs(v))
values(p) <- data.frame(pid=1:2, value=expanse(p))
u <- union(v, p)
plot(u, "pid")

b <- buffer(v, 1000)

u <- union(b)
u$sum <- rowSums(as.data.frame(u))
plot(u, "sum")

terra documentation built on April 12, 2025, 1:43 a.m.