Reads GeoTIFF files from a directory OR combines already-loaded SpatRasters. Computes the union of their extents, resamples them to a common grid, and returns a single multilayer SpatRaster.
Arguments
- raster_list
Optional list of SpatRaster objects already loaded in R. If provided, dir_path and pattern are ignored.
- dir_path
Character. Directory containing input GeoTIFF files. Only used if raster_list is NULL.
- pattern
Character. Pattern that file names must contain. Only used if raster_list is NULL.
- method
Character. Resampling method passed to terra::resample(), e.g. "bilinear" (default) or "near" for categorical data.
Value
A single multilayer SpatRaster with one layer per input. Layers are named from list names or file basenames without extension.
Details
The first raster (file or list element) defines the target resolution, origin and CRS; the union of all extents defines the spatial coverage. Areas where a raster has no data are filled with NA.
Examples
# \donttest{
library(terra)
# Create 3 separate rasters with different extents
r1 <- rast(ncol = 30, nrow = 30, xmin = 0, xmax = 10,
ymin = 0, ymax = 10, crs = "EPSG:4326")
values(r1) <- runif(ncell(r1), 0, 100)
r2 <- rast(ncol = 30, nrow = 30, xmin = 1, xmax = 11,
ymin = 1, ymax = 11, crs = "EPSG:4326")
values(r2) <- runif(ncell(r2), 0, 100)
r3 <- rast(ncol = 30, nrow = 30, xmin = -1, xmax = 9,
ymin = -1, ymax = 9, crs = "EPSG:4326")
values(r3) <- runif(ncell(r3), 0, 100)
# Combine into single multilayer SpatRaster
raster_list <- list(baseline = r1, future_A = r2, future_B = r3)
combined <- combine.rasters(raster_list = raster_list)
combined
#> class : SpatRaster
#> size : 36, 36, 3 (nrow, ncol, nlyr)
#> resolution : 0.3333333, 0.3333333 (x, y)
#> extent : -1, 11, -1, 11 (xmin, xmax, ymin, ymax)
#> coord. ref. : lon/lat WGS 84 (EPSG:4326)
#> source(s) : memory
#> names : baseline, future_A, future_B
#> min values : 0.3315152, 0.174157, 0.132205
#> max values : 99.9023285, 99.964592, 99.983269
# }