gdalcubes/R/join_bands.R

91 lines
2.9 KiB
R

#' Join bands of two identically shaped data cubes
#'
#' Create a proxy data cube, which joins the bands of two identically shaped data cubes. The resulting cube
#' will have bands from both input cubes.
#'
#' @param cube_list a list with two or more source data cubes
#' @param cube_names list or character vector with optional name prefixes for bands in the output data cube (see Details)
#' @return proxy data cube object
#' @examples
#' # create image collection from example Landsat data only
#' # if not already done in other examples
#' if (!file.exists(file.path(tempdir(), "L8.db"))) {
#' L8_files <- list.files(system.file("L8NY18", package = "gdalcubes"),
#' ".TIF", recursive = TRUE, full.names = TRUE)
#' create_image_collection(L8_files, "L8_L1TP", file.path(tempdir(), "L8.db"), quiet = TRUE)
#' }
#'
#' L8.col = image_collection(file.path(tempdir(), "L8.db"))
#' v = cube_view(extent=list(left=388941.2, right=766552.4,
#' bottom=4345299, top=4744931, t0="2018-01", t1="2018-05"),
#' srs="EPSG:32618", nx = 497, ny=526, dt="P1M")
#' L8.cube = raster_cube(L8.col, v)
#' L8.cube.b04 = select_bands(raster_cube(L8.col, v), c("B04"))
#' L8.cube.b05 = select_bands(raster_cube(L8.col, v), c("B05"))
#' join_bands(list(L8.cube.b04,L8.cube.b05))
#' \donttest{
#' plot(join_bands(list(L8.cube.b04,L8.cube.b05)))
#' }
#' @note This function returns a proxy object, i.e., it will not start any computations besides deriving the shape of the result.
#' @details
#' The number of provided cube_names must match the number of provided input cubes.
#' If no cube_names are provided, bands of the output cube will adopt original names from the input cubes (without any prefix). If any two of the input bands have identical names,
#' prefixes default prefixes ("X1", "X2", ...) will be used.
#'
#' @export
join_bands <- function(cube_list, cube_names = NULL) {
ncubes = length(cube_list)
stopifnot(is.list(cube_list))
stopifnot(length(cube_list) > 1)
for (i in 1:ncubes) {
stopifnot(is.cube(cube_list[[i]]))
}
if (is.null(cube_names)) {
names = character()
for (i in 1:ncubes) {
names = c(names, names(cube_list[i]))
}
if (anyDuplicated(names) > 0) {
cube_names = paste0("X", 1:ncubes)
}
else {
cube_names = character()
}
}
else {
if (is.list(cube_names)) {
cube_names = as.character(unlist(cube_names))
}
stopifnot(length(cube_names) == ncubes)
stopifnot(is.vector(cube_names))
stopifnot(is.character(cube_names))
}
x = gc_create_join_bands_cube(cube_list, cube_names)
class(x) <- c("join_bands_cube", "cube", "xptr")
return(x)
}
is.join_bands_cube <- function(obj) {
if(!("join_bands_cube" %in% class(obj))) {
return(FALSE)
}
if (gc_is_null(obj)) {
warning("GDAL data cube proxy object is invalid")
return(FALSE)
}
return(TRUE)
}