Extract values from a SpatRaster, SpatVector or SpatExtent

Extract values from a SpatRaster; a subset of records (row) and/or variables (columns) from a SpatVector; or a number from a SpatExtent.

You can use indices (row, column, layer or cell numbers) to extract. You can also use other Spat* objects.

# S4 method for SpatRaster,ANY,ANY,ANY
[(x, i, j, k)

# S4 method for SpatVector,numeric,numeric
[(x, i, j, drop=FALSE)

# S4 method for SpatVector,SpatVector,missing
[(x, i, j)

# S4 method for SpatExtent,numeric,missing
[(x, i, j)

Arguments

x

SpatRaster, SpatVector or SpatExtent

i

if x is a SpatRaster: numeric, logical or missing to select rows or, if j is missing, to select cells numbers.

if x is a SpatVector: numeric or missing to select rows. if i is another SpatVector: get a new SpatVector with the geometries that intersect.

if x is a SpatExtent: integer between 1 and 4.

j

numeric, logical, or missing to select columns

k

numeric, character, or missing to select layers

drop

logical. If FALSE an object of the same class as x is returned

Value

numeric if x is a SpatExtent. Same as x if drop=FALSE. Otherwise a data.frame

See also

linkextract, link{subset}, link{$}, link{[[},

Examples

### SpatRaster
f <- system.file("ex/elev.tif", package="terra")
r <- rast(f)
r[3638]
#>   elevation
#> 1       473
rowColFromCell(r, 2638)
#>      [,1] [,2]
#> [1,]   28   73
r[39, 28]
#>   elevation
#> 1       473
x <- r[39:40, 28:29, drop=FALSE] 
as.matrix(x, wide=TRUE)
#>      [,1] [,2]
#> [1,]  473  429
#> [2,]  430  436

### SpatVector

v <- vect(system.file("ex/lux.shp", package="terra"))
v[2:3,]
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 2, 6  (geometries, attributes)
#>  extent      : 5.746118, 6.315773, 49.69933, 49.98745  (xmin, xmax, ymin, ymax)
#>  coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#>  names       :  ID_1   NAME_1  ID_2   NAME_2  AREA   POP
#>  type        : <num>    <chr> <num>    <chr> <num> <int>
#>  values      :     1 Diekirch     2 Diekirch   218 32543
#>                    1 Diekirch     3  Redange   259 18664
v[1:2, 2:3]
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 2, 2  (geometries, attributes)
#>  extent      : 5.826232, 6.315773, 49.78479, 50.18162  (xmin, xmax, ymin, ymax)
#>  coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#>  names       :   NAME_1  ID_2
#>  type        :    <chr> <num>
#>  values      : Diekirch     1
#>                Diekirch     2
v[1:2, 2:3, drop=TRUE]
#>     NAME_1 ID_2
#> 1 Diekirch    1
#> 2 Diekirch    2