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Scale a raster object’s values to a range between 0 and 1

Source: R/spat_scale_0_1.R
scale_0_1.Rd

Scales the values of a SpatRaster (from the terra package), Raster* (from the raster package), or a raster file loaded via terra::rast() to a range between 0 and 1.

Usage

scale_0_1(raster)

Arguments

raster

A SpatRaster, RasterLayer, RasterStack, RasterBrick object, or a character string specifying the path to a raster file that can be loaded with terra::rast() (e.g., GeoTIFF, NetCDF).

Value

A SpatRaster object with all values scaled between 0 and 1.

Note

This function accepts a SpatRaster, Raster* object, or a file path. Raster* objects are coerced to SpatRaster using terra::rast(), and file paths are loaded as SpatRaster. It calculates the minimum and maximum values and scales all values between 0 and 1.

Author

Ahmed El-Gabbas

Examples

ecokit::load_packages(terra, raster, fs, ggplot2, tidyterra)

# Setup temporary directory
temp_dir <- fs::path_temp("scale_0_1")
fs::dir_create(temp_dir)

# Example with SpatRaster
r <- terra::rast(ncols = 10, nrows = 10)
terra::values(r) <- rnorm(terra::ncell(r))
r_scaled <- scale_0_1(r)
c(r, r_scaled)
#> class       : SpatRaster 
#> size        : 10, 10, 2  (nrow, ncol, nlyr)
#> resolution  : 36, 18  (x, y)
#> extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
#> coord. ref. : lon/lat WGS 84 (CRS84) (OGC:CRS84) 
#> source(s)   : memory
#> names       :     lyr.1, lyr.1 
#> min values  : -2.525689,     0 
#> max values  :  1.707957,     1 

# Example with RasterLayer
r_raster <- raster::raster(ncol = 10, nrow = 10)
raster::values(r_raster) <- rnorm(raster::ncell(r_raster))
r_raster_scaled <- scale_0_1(r_raster)
c(r_raster, r_raster_scaled)
#> [[1]]
#> class      : RasterLayer 
#> dimensions : 10, 10, 100  (nrow, ncol, ncell)
#> resolution : 36, 18  (x, y)
#> extent     : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
#> crs        : +proj=longlat +datum=WGS84 +no_defs 
#> source     : memory
#> names      : layer 
#> values     : -2.071058, 2.020903  (min, max)
#> 
#> 
#> [[2]]
#> class       : SpatRaster 
#> size        : 10, 10, 1  (nrow, ncol, nlyr)
#> resolution  : 36, 18  (x, y)
#> extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
#> coord. ref. : +proj=longlat +datum=WGS84 +no_defs 
#> source(s)   : memory
#> name        : lyr.1 
#> min value   :     0 
#> max value   :     1 
#> 

# Example with file path
r_file <- fs::path(temp_dir, "raster.tif")
terra::writeRaster(r, r_file, overwrite = TRUE)
r_file_scaled <- scale_0_1(r_file)
c(terra::rast(r_file), r_file_scaled)
#> class       : SpatRaster 
#> size        : 10, 10, 2  (nrow, ncol, nlyr)
#> resolution  : 36, 18  (x, y)
#> extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
#> coord. ref. : lon/lat WGS 84 (EPSG:4326) 
#> sources     : raster.tif  
#>               memory  
#> names       :     lyr.1, lyr.1 
#> min values  : -2.525689,     0 
#> max values  :  1.707957,     1 

# Visualize results
ggplot2::ggplot() +
  tidyterra::geom_spatraster(data = r, maxcell = Inf) +
  ggplot2::theme_minimal()


ggplot2::ggplot() +
  tidyterra::geom_spatraster(data = r_scaled, maxcell = Inf) +
  ggplot2::theme_minimal()


# clean up
fs::dir_delete(temp_dir)