reverse axis order for short codes in generated grids

Author: e-kotov

R/backend_sequential.R

@@ -10,12 +10,14 @@ create_grid_internal <- function(
   use_convex_hull = FALSE,
   buffer_m = 0,
   id_format = c("both", "long", "short", "none"),
+  axis_order = c("NE", "EN"),
   include_llc = TRUE,
   point_type = c("centroid", "llc")
 ) {
   # --- 1. PRE-CHECKS AND HELPERS ---
   output_type <- match.arg(output_type)
   id_format <- match.arg(id_format)
+  axis_order <- match.arg(axis_order)
   point_type <- match.arg(point_type)
 
   if (!requireNamespace("sf", quietly = TRUE)) {
@@ -40,12 +42,21 @@ create_grid_internal <- function(
     }
     n
   }
-  make_ids <- function(x_llc, y_llc, cs, epsg = 3035) {
+  make_ids <- function(x_llc, y_llc, cs, axis_order, epsg = 3035) {
     nzeros <- tz_count(cs)
     div <- as.integer(10^nzeros)
     size_lbl <- if (cs >= 1000) paste0(cs / 1000, "km") else paste0(cs, "m")
+
+    # Long IDs are strictly N...E according to INSPIRE spec, so we don't change this.
     id_long <- sprintf("CRS%sRES%smN%.0fE%.0f", epsg, cs, y_llc, x_llc)
-    id_short <- sprintf("%sN%.0fE%.0f", size_lbl, y_llc / div, x_llc / div)
+
+    # Short IDs support swapping order
+    id_short <- if (axis_order == "NE") {
+      sprintf("%sN%.0fE%.0f", size_lbl, y_llc / div, x_llc / div)
+    } else {
+      sprintf("%sE%.0fN%.0f", size_lbl, x_llc / div, y_llc / div)
+    }
+
     list(long = id_long, short = id_short)
   }
 
@@ -197,6 +208,7 @@ create_grid_internal <- function(
       out_obj$X_LLC,
       out_obj$Y_LLC,
       cellsize_m,
+      axis_order = axis_order,
       epsg = grid_crs$epsg %||% 3035
     )
     if (id_format == "long") {

R/create_grid.R

@@ -35,6 +35,13 @@
 #'   clipping. Defaults to `0` (no buffer).
 #' @param id_format A character string specifying which grid cell IDs to generate.
 #'   Options are `"both"` (default), `"long"`, `"short"`, or `"none"`.
+#' @param axis_order A character string specifying the coordinate order for the
+#'   output Short INSPIRE IDs. This parameter is **only used when `id_format` is
+#'   `"short"` or `"both"`**. It can be one of:
+#'   \itemize{
+#'     \item `"NE"` (the default) to produce the format `{cellsize}N{y}E{x}`.
+#'     \item `"EN"` to produce the format `{cellsize}E{x}N{y}` (e.g. this format is used in [Danish national grid](https://www.dst.dk/en/TilSalg/produkter/geodata/kvadratnet)).
+#'   }
 #' @param include_llc A logical value. If `TRUE` (default), columns for the
 #'   lower-left corner coordinates (`X_LLC`, `Y_LLC`) of each cell are included
 #'   in the output.
@@ -108,6 +115,7 @@ create_grid <- function(
   use_convex_hull = FALSE,
   buffer_m = 0,
   id_format = "both",
+  axis_order = "NE",
   include_llc = TRUE,
   point_type = "centroid",
   parallel = "auto",
@@ -176,6 +184,7 @@ create_grid <- function(
     use_convex_hull = use_convex_hull,
     buffer_m = buffer_m,
     id_format = id_format,
+    axis_order = axis_order,
     include_llc = include_llc,
     point_type = point_type,
     ...

man/create_grid.Rd

@@ -416,3 +416,63 @@ test_that("Memory warning is triggered with insufficient (fake) RAM", {
   # Ensure the option is unset and doesn't interfere with other tests
   expect_null(getOption("gridmaker.fake_ram"))
 })
+
+test_that("create_grid respects axis_order argument for Short IDs", {
+  # Use a simple bounding box for testing
+  # 10km grid
+  # LLC at 0,0
+  simple_extent <- sf::st_bbox(c(xmin = 0, ymin = 0, xmax = 20000, ymax = 10000), crs = 3035)
+  cellsize <- 10000
+
+  # 1. Test Default (NE)
+  grid_ne <- create_grid(
+    simple_extent,
+    cellsize_m = cellsize,
+    id_format = "short",
+    axis_order = "NE",
+    quiet = TRUE
+  )
+
+  # Expect format: 10kmN0E0 (Northing then Easting)
+  # Check the first ID (LLC 0,0)
+  expected_ne <- "10kmN0E0"
+  expect_true(expected_ne %in% grid_ne$GRD_ID)
+
+  # 2. Test EN Order
+  grid_en <- create_grid(
+    simple_extent,
+    cellsize_m = cellsize,
+    id_format = "short",
+    axis_order = "EN",
+    quiet = TRUE
+  )
+
+  # Expect format: 10kmE0N0 (Easting then Northing)
+  expected_en <- "10kmE0N0"
+  expect_true(expected_en %in% grid_en$GRD_ID)
+
+  # 3. Test that Long IDs are NOT affected (Must remain N...E for standard compliance)
+  grid_both_en <- create_grid(
+    simple_extent,
+    cellsize_m = cellsize,
+    id_format = "both",
+    axis_order = "EN",
+    quiet = TRUE
+  )
+
+  # Short ID should be EN
+  expect_true("10kmE0N0" %in% grid_both_en$GRD_ID_SHORT)
+
+  # Long ID should still be NE (CRS...RES...N...E...)
+  # 0,0 is usually N0E0
+  long_id <- grid_both_en$GRD_ID_LONG[grid_both_en$GRD_ID_SHORT == "10kmE0N0"]
+  expect_true(grepl("N0E0", long_id))
+  expect_false(grepl("E0N0$", long_id)) # Should not end in E...N...
+})
+
+test_that("create_grid throws error for invalid axis_order", {
+  expect_error(
+    create_grid(nc, CELLSIZE, axis_order = "XY"),
+    regexp = "'arg' should be one of"
+  )
+})