Grow a categorical SpatRaster by certain amount of pixels or distance.

A common issue in aggregating categorical rasters is that coastal and boundary gridcells tend to decrease owing to aggregation effects. This can cause issues of non-matching grid cells later on. This simple function takes a categorical SpatRaster object and grows it into no-data areas (those with NA values) within an optionally provided distance.

Usage

spl_growGrid(x, iter = 2)

Arguments

x

A categorical SpatRaster to be grown.

iter

A numeric values of the maximum number of iterations from the grid cell border of which x should be grown (Default: 2).

Value

SpatRaster

Note

Only NA grid cells will be filled!

See also

buffer, focal

Examples

set.seed(42)
ras <- terra::rast(ncol = 100, nrow = 100, xmin = 0, xmax = 100,
ymin = 0, ymax = 100, resolution = 10, crs = NA)

# Fill with dummy values but keep half as NA
terra::values(ras) <- c(rep(NA,50),rbinom(terra::ncell(ras)/2, 10, 0.5))

# Convert to factor
ras <- terra::as.factor(ras)
assertthat::assert_that(terra::is.factor(ras))
#> [1] TRUE

ras_nona <- spl_growGrid(x = ras, iter = 10)
terra::plot(ras_nona)