R/mask_with_fuelmodel.R

In ecmwf/caliver: Calibration and Verification of Gridded Model Outputs

#' @title mask_with_fuelmodel
#'
#' @description This function masks a Raster* object using JRC's fuelmodel.
#'
#' @param x Raster* to mask
#' @param fuelmap Custom fuel map as RasterLayer.
#' @param codes The value of the cells in fuelmap used to mask x.
#' @param value The value of cells masked out by the fuel map (NA by default).
#'
#' @details In absence of vegetation the risk of ignition reduces considerably,
#' regardless of the state of the soil. These areas are mapped in the JRC's
#' fuelmodel (in use in 2018). This package contains a cached version of this
#' map (matching crs and resolution of ERA-Interim),
#' stored in the 'inst/extdata' folder of the package. For evaluating fire
#' danger we use this map to mask deserts, glaciers, urban areas, etc. These
#' areas have codes > 20. The optional argument `fuelmap` allows to input a
#' custom fuelmap and costum `codes` to use for masking.
#' Please note that
#'
#' @export
#'
#' @examples
#' \dontrun{
#'   xmasked <- mask_with_fuelmodel(x)
#' }
#'

mask_with_fuelmodel <- function(x, fuelmap = NULL, codes = NULL, value = NA){

  if (!is.null(fuelmap) & is.null(codes)){
    stop("Please provide codes to be used with custom fuelmap")
  }

  if (is.null(fuelmap)){
    # Load JRC fuelmodel map (longitudes in range [0, 360])
    fuelmodel_file_path <- system.file(file.path("extdata",
                                                 "clim_fuelmodel.nc"),
                                       package = "caliver")
    fuelmap <- raster::raster(fuelmodel_file_path)
    # Deserts, glaciers, urban areas, etc. in the dummy fuelmap have codes 21:26
    codes <- 21:26
  }

  # Compare rasters
  if (raster::compareRaster(x, fuelmap)) {

    # Remove areas with specific codes
    for (code in codes){
      fuelmap[fuelmap == code] <- NA
    }

    # Mask x using fuelmap
    xmasked <- raster::mask(x, fuelmap, updatevalue = value, progress = "text")

  }

  return(xmasked)

}