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Subset a SpatRaster or a SpatVector

subset.Rd

Select a subset of layers from a SpatRaster or select a subset of records (row) and/or variables (columns) from a SpatVector.

Usage

# S4 method for class 'SpatRaster'
subset(x, subset, negate=FALSE, NSE=FALSE, filename="", overwrite=FALSE, ...)

# S4 method for class 'SpatVector'
subset(x, subset, select, drop=FALSE, NSE=FALSE)

Arguments

x

SpatRaster or SpatVector

subset

if x is a SpatRaster: integer or character to select layers

if x is a SpatVector: logical expression indicating the rows to keep (missing values are taken as FALSE)

select

expression, indicating columns to select

negate

logical. If TRUE all layers that are not in the subset are selected

NSE

logical. If TRUE, non-standard evaluation (the use of unquoted variable names) is allowed. Set this to FALSE when calling subset from a function

drop

logical. If TRUE, the geometries will be dropped, and a data.frame is returned

filename

character. Output filename

overwrite

logical. If TRUE, filename is overwritten

...

additional arguments for writing files as in writeRaster

Value

if x is a SpatRaster: SpatRaster

if x is a SpatVector: SpatVector or, if drop=TRUE, a data.frame.

Examples

### SpatRaster
s <- rast(system.file("ex/logo.tif", package="terra"))   
subset(s, 2:3)
#> class       : SpatRaster 
#> dimensions  : 77, 101, 2  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> names       : green, blue 
#> min values  :     0,    0 
#> max values  :   255,  255 
subset(s, c(3,2,3,1))
#> class       : SpatRaster 
#> dimensions  : 77, 101, 4  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> names       : blue, green, blue, red 
#> min values  :    0,     0,    0,   0 
#> max values  :  255,   255,  255, 255 

#equivalent to 
s[[ c(3,2,3,1) ]]
#> class       : SpatRaster 
#> dimensions  : 77, 101, 4  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> names       : blue, green, blue, red 
#> min values  :    0,     0,    0,   0 
#> max values  :  255,   255,  255, 255 

s[[c("red", "green")]]
#> class       : SpatRaster 
#> dimensions  : 77, 101, 2  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> names       : red, green 
#> min values  :   0,     0 
#> max values  : 255,   255 
s$red
#> class       : SpatRaster 
#> dimensions  : 77, 101, 1  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> name        : red 
#> min value   :   0 
#> max value   : 255 

# expression based (partial) matching of names with single brackets
s["re"]
#> class       : SpatRaster 
#> dimensions  : 77, 101, 2  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> names       : red, green 
#> min values  :   0,     0 
#> max values  : 255,   255 
s["^re"]
#> class       : SpatRaster 
#> dimensions  : 77, 101, 1  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : 0, 101, 0, 77  (xmin, xmax, ymin, ymax)
#> coord. ref. : Cartesian (Meter) 
#> source      : logo.tif 
#> name        : red 
#> min value   :   0 
#> max value   : 255 

# not with double brackets
# s[["re"]]


### SpatVector

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

subset(v, v$NAME_1 == "Diekirch", c("NAME_1", "NAME_2"))
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 5, 2  (geometries, attributes)
#>  extent      : 5.74414, 6.315773, 49.69933, 50.18162  (xmin, xmax, ymin, ymax)
#>  coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#>  names       :   NAME_1   NAME_2
#>  type        :    <chr>    <chr>
#>  values      : Diekirch Clervaux
#>                Diekirch Diekirch
#>                Diekirch  Redange

subset(v, NAME_1 == "Diekirch", c(NAME_1, NAME_2), NSE=TRUE)
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 5, 2  (geometries, attributes)
#>  extent      : 5.74414, 6.315773, 49.69933, 50.18162  (xmin, xmax, ymin, ymax)
#>  coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#>  names       :   NAME_1   NAME_2
#>  type        :    <chr>    <chr>
#>  values      : Diekirch Clervaux
#>                Diekirch Diekirch
#>                Diekirch  Redange

# or like this
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, c("NAME_1", "NAME_2")]
#>  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   NAME_2
#>  type        :    <chr>    <chr>
#>  values      : Diekirch Clervaux
#>                Diekirch Diekirch