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rspatialterra

`sp::over()` equivalent in `terra`

Is there an equivalent of sp::over() in package terra? To get a data frame showing which geometries of a SpatVector overlay which geometries of another SpatVector -- like this, but using only terra:

# get a polygons map:
library(terra)
lux <- vect(system.file("ex/lux.shp", package="terra"))
plot(lux)
text(lux, lux$NAME_2)

# get points that overlay some of those polygons:
pts <- vect(cbind(c(5.8, 6, 6.2), c(49.85, 49.5, 49.6)), crs = crs(lux))
plot(pts, col = "blue", add = TRUE)

# find which points overlay which polygons:
library(sp); library(raster)
over(as(pts, "Spatial"), as(lux, "Spatial"))

#   ID_1     NAME_1 ID_2           NAME_2 AREA    POP
# 1    1   Diekirch    3          Redange  259  18664
# 2    3 Luxembourg    9 Esch-sur-Alzette  251 176820
# 3    3 Luxembourg   10       Luxembourg  237 182607

enter image description here

Solution

  • Your example data

    library(terra)
lux <- vect(system.file("ex/lux.shp", package="terra"))
pts <- vect(cbind(c(5.8, 6, 6.2), c(49.85, 49.5, 49.6)), crs = crs(lux))

    You can use extract (also in raster)

    extract(lux, pts)[,-1]
#  ID_1     NAME_1 ID_2           NAME_2 AREA    POP
#1    1   Diekirch    3          Redange  259  18664
#2    3 Luxembourg    9 Esch-sur-Alzette  251 176820
#3    3 Luxembourg   10       Luxembourg  237 182607

    Or you can do (a variation on the solution by lovalery)

    i <- relate(pts, lux, "within") |> apply(2, any)
lux[i,] |> data.frame()
#  ID_1     NAME_1 ID_2           NAME_2 AREA    POP
#1    1   Diekirch    3          Redange  259  18664
#2    3 Luxembourg    9 Esch-sur-Alzette  251 176820
#3    3 Luxembourg   10       Luxembourg  237 182607

    Or simply like this

    i <- is.related(lux, pts, "intersects")
lux[i,] |> data.frame()
#  ID_1     NAME_1 ID_2           NAME_2 AREA    POP
#1    1   Diekirch    3          Redange  259  18664
#2    3 Luxembourg    9 Esch-sur-Alzette  251 176820
#3    3 Luxembourg   10       Luxembourg  237 182607