union: Union SpatVector or SpatExtent objects

In terra: Spatial Data Analysis

Union SpatVector or SpatExtent objects

Description

Overlapping polygons (between, not within, objects) are intersected. Union for lines and points simply combines the two data sets; without any geometric intersections. This is equivalent to c. Attributes are joined. See c if you want to combine polygons without intersection.

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

intersect

merge and mosaic to union SpatRaster objects.

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 Oct. 13, 2023, 5:08 p.m.