Skip to contents

Convert a qgis_result object or one of its elements to a terra object

Source: R/compat-terra.R
qgis_as_terra.Rd

This function performs coercion to one of the terra classes SpatRaster, SpatVector or SpatVectorProxy (add proxy = TRUE for the latter). The distinction between SpatRaster and SpatVector is based on the output type.

Usage

qgis_as_terra(x, ...)

# S3 method for class 'qgis_outputRaster'
qgis_as_terra(x, ...)

# S3 method for class 'qgis_outputLayer'
qgis_as_terra(x, ...)

# S3 method for class 'qgis_outputVector'
qgis_as_terra(x, ...)

# S3 method for class 'qgis_result'
qgis_as_terra(x, ...)

Arguments

x

A qgis_result object from qgis_run_algorithm() or a qgis_output* object from one of the qgis_extract_output() functions.

...

Arguments passed to terra::rast() or terra::vect(), depending on the output type of x (or one of its elements, if x is a qgis_result).

Value

A SpatRaster, SpatVector or SpatVectorProxy object.

See also

Other topics about coercing processing output: qgis_as_raster(), st_as_sf, st_as_stars

Other topics about accessing or managing processing results: qgis_as_raster(), qgis_clean_result(), qgis_extract_output(), qgis_result_status(), st_as_sf, st_as_stars

Examples

# \donttest{
# not running below examples in R CMD check to save time
result <- qgis_run_algorithm(
  "native:slope",
  INPUT = system.file("longlake/longlake_depth.tif", package = "qgisprocess")
)
#> Argument `Z_FACTOR` is unspecified (using QGIS default value).
#> Using `OUTPUT = qgis_tmp_raster()`

# most direct approach, autoselecting a `qgis_outputRaster` type
# output from the `result` object and reading as SpatRaster:
qgis_as_terra(result)
#> class       : SpatRaster 
#> dimensions  : 100, 100, 1  (nrow, ncol, nlyr)
#> resolution  : 18.27273, 15.53535  (x, y)
#> extent      : 409939.9, 411767.1, 5083307, 5084861  (xmin, xmax, ymin, ymax)
#> coord. ref. : NAD83 / UTM zone 20N (EPSG:26920) 
#> source      : file2bd75d9eaaa9.tif 
#> name        : file2bd75d9eaaa9 

# if you need more control, extract the needed output element first:
output_raster <- qgis_extract_output(result, "OUTPUT")
qgis_as_terra(output_raster)
#> class       : SpatRaster 
#> dimensions  : 100, 100, 1  (nrow, ncol, nlyr)
#> resolution  : 18.27273, 15.53535  (x, y)
#> extent      : 409939.9, 411767.1, 5083307, 5084861  (xmin, xmax, ymin, ymax)
#> coord. ref. : NAD83 / UTM zone 20N (EPSG:26920) 
#> source      : file2bd75d9eaaa9.tif 
#> name        : file2bd75d9eaaa9 

# Same holds for coercion to SpatVector
result2 <- qgis_run_algorithm(
  "native:buffer",
  INPUT = system.file("longlake/longlake.gpkg", package = "qgisprocess"),
  DISTANCE = 100
)
#> Argument `SEGMENTS` is unspecified (using QGIS default value).
#> Using `END_CAP_STYLE = "Round"`
#> Using `JOIN_STYLE = "Round"`
#> Argument `MITER_LIMIT` is unspecified (using QGIS default value).
#> Argument `DISSOLVE` is unspecified (using QGIS default value).
#> Argument `SEPARATE_DISJOINT` is unspecified (using QGIS default value).
#> Using `OUTPUT = qgis_tmp_vector()`

qgis_as_terra(result2)
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 1, 1  (geometries, attributes)
#>  extent      : 409850.6, 411856.3, 5083216, 5084951  (xmin, xmax, ymin, ymax)
#>  source      : file2bd76d0ab1b1.gpkg
#>  coord. ref. : NAD83 / UTM zone 20N (EPSG:26920) 
#>  names       :     label
#>  type        :     <chr>
#>  values      : Long Lake
output_vector <- qgis_extract_output(result2, "OUTPUT")
qgis_as_terra(output_vector)
#>  class       : SpatVector 
#>  geometry    : polygons 
#>  dimensions  : 1, 1  (geometries, attributes)
#>  extent      : 409850.6, 411856.3, 5083216, 5084951  (xmin, xmax, ymin, ymax)
#>  source      : file2bd76d0ab1b1.gpkg
#>  coord. ref. : NAD83 / UTM zone 20N (EPSG:26920) 
#>  names       :     label
#>  type        :     <chr>
#>  values      : Long Lake

# SpatVectorProxy:
qgis_as_terra(result2, proxy = TRUE)
#>  class       : SpatVectorProxy
#>  geometry    : polygons 
#>  dimensions  : 1, 1  (geometries, attributes)
#>  extent      : 409850.6, 411856.3, 5083216, 5084951  (xmin, xmax, ymin, ymax)
#>  source      : file2bd76d0ab1b1.gpkg
#>  coord. ref. : NAD83 / UTM zone 20N (EPSG:26920) 
#>  names       : label
#>  type        : <chr>
# }