Migrate from raster to terra and fix CRAN archival failure

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: slopes
 Title: Calculate Slopes of Roads, Rivers and Trajectories
-Version: 1.0.1.9000
+Version: 1.0.2
 Authors@R: c(
     person("Robin", "Lovelace", email = "rob00x@gmail.com", role = c("aut", "cre", "cph"),
       comment = c(ORCID = "0000-0001-5679-6536")),
@@ -25,18 +25,16 @@ BugReports: https://github.com/ropensci/slopes/issues
 Encoding: UTF-8
 LazyData: true
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.3.2
 Imports: 
     sf,
-    raster,
+    terra,
     methods,
     pbapply,
     geodist,
     colorspace
 Depends: 
     R (>= 2.10)
 Suggests: 
-    terra,
     knitr,
     rmarkdown,
     ceramic,
@@ -53,3 +51,4 @@ Suggests:
 Config/Needs/website: generics
 VignetteBuilder: knitr
 Config/testthat/edition: 3
+Config/roxygen2/version: 8.0.0

NAMESPACE

@@ -1,5 +1,6 @@
 # Generated by roxygen2: do not edit by hand
 
+export(dem_lisbon)
 export(elevation_add)
 export(elevation_extract)
 export(elevation_get)

NEWS.md

@@ -1,7 +1,22 @@
-# slopes (development version)
+# slopes 1.0.2
+
+* Migrated from the deprecated `raster` package to `terra` (closes #60).
+  `terra` is now a hard dependency (`Imports`); `raster` is no longer required.
+* `elevation_extract()`, `slope_raster()`, and `elevation_add()` now always use
+  `terra`. The `terra =` argument is deprecated (with a message) and ignored.
+* `elevation_get()` now always returns a `SpatRaster`. The `output_format =`
+  argument is deprecated and ignored.
+* `slope_matrix_to_raster()` and `slope_xyz_simple()` now work with `SpatRaster`
+  objects. Legacy `Raster*` objects are accepted with an automatic conversion
+  message for backwards compatibility.
+* The bundled dataset has been renamed from `dem_lisbon_raster` to `dem_lisbon`
+  and is now a `SpatRaster` object (was a `RasterLayer`).
+* Fixed CRAN `--run-donttest` failure: the `ceramic`/Mapbox-dependent example in
+  `elevation_add()` is now wrapped in `\dontrun{}` instead of `\donttest{}` (closes #72).
 
 # slopes 1.0.1
 
+
 * Package source code now hosted at https://github.com/ropensci/slopes
 * New documentation section showing how directed routes work: https://docs.ropensci.org/slopes/articles/slopes.html#splitting-the-network
 

R/data.R

@@ -1,12 +1,23 @@
 
+#' Read the bundled Lisbon DEM as a SpatRaster
+#'
+#' Returns a `SpatRaster` (terra package) of the Digital Elevation Model
+#' for central Lisbon, Portugal, bundled with the slopes package.
+#'
+#' @return A `SpatRaster` object with 133 rows, 200 columns, and 1 elevation layer.
+#' @export
+#' @examples
+#' dem_lisbon()
+dem_lisbon <- function() {
+  tif <- system.file("dem_lisbon.tif", package = "slopes")
+  if (!nzchar(tif)) stop("dem_lisbon.tif not found in slopes package installation.")
+  terra::rast(tif)
+}
+
 #' Cycle route data
 #' @format An sf object
 "cyclestreets_route"
 
-#' Lisbon elevation raster
-#' @format A raster object
-"dem_lisbon_raster"
-
 #' Lisbon road network
 #' @format An sf object
 "lisbon_road_network"

R/slope_get.R

@@ -1,31 +1,23 @@
 #' Get elevation data for routes
 #'
 #' Downloads elevation data using the ceramic package for given routes.
+#' Returns a `SpatRaster` object (terra package).
 #'
 #' @param routes An sf object containing linestring geometries
 #' @param ... Additional arguments passed to ceramic::cc_elevation
-#' @param output_format Character string specifying output format ("raster" or "terra")
-#' @return Elevation raster data covering the routes
+#' @return A SpatRaster covering the routes
 #' @export
-elevation_get = function(routes, ..., output_format = "raster") {
-  if(requireNamespace("ceramic")) {
-    mid_ext = sf_mid_ext_lonlat(routes)
-    bw = max(c(mid_ext$width, mid_ext$height)) / 1 # buffer width
-    suppressWarnings({
-      e = ceramic::cc_elevation(loc = mid_ext$midpoint, buffer = bw, ...)
-    })
-  } else {
-    message("Install the package ceramic")
+elevation_get = function(routes, ...) {
+  if (!requireNamespace("ceramic", quietly = TRUE)) {
+    stop("Install the package ceramic to use elevation_get().")
   }
+  mid_ext = sf_mid_ext_lonlat(routes)
+  bw = max(c(mid_ext$width, mid_ext$height)) / 1 # buffer width
+  suppressWarnings({
+    e = ceramic::cc_elevation(loc = mid_ext$midpoint, buffer = bw, ...)
+  })
   crs_routes = sf::st_crs(routes)
-  if(!requireNamespace("terra", quietly = TRUE)) {
-    message('install.packages("terra") # for this to work')
-  }
-  res = terra::project(e, y = crs_routes$wkt)
-  if(output_format == "raster") {
-    res = raster::raster(res)
-  }
-  res
+  terra::project(e, y = crs_routes$wkt)
 }
 
 #' Extract midpoint and extent from routes in lonlat
@@ -49,39 +41,50 @@ sf_mid_ext_lonlat = function(routes) {
   res
 }
 
-#' Convert slope matrix to raster
+#' Convert slope matrix to SpatRaster
 #'
-#' Converts a slope matrix or checks if input is already a raster.
+#' Converts a slope matrix or a legacy RasterLayer to a SpatRaster (terra).
+#' Accepts `SpatRaster`, legacy `Raster*`, or a plain matrix.
 #'
-#' @param x A matrix or RasterLayer object
-#' @return A RasterLayer object
+#' @param x A matrix, SpatRaster, or legacy RasterLayer object
+#' @return A SpatRaster object
 #' @export
-slope_matrix_to_raster <- function(x) {  # <-- Changed name
-  if (inherits(x, "Raster")) {
+slope_matrix_to_raster <- function(x) {
+  if (methods::is(x, "SpatRaster")) {
     return(x)
   }
+  if (methods::is(x, "Raster")) {
+    message("Converting legacy Raster* object to SpatRaster. Consider using terra::rast() directly.")
+    return(terra::rast(x))
+  }
   if (is.matrix(x)) {
-    return(raster::raster(x))
+    return(terra::rast(x))
   }
-  stop("Input must be a matrix or RasterLayer")
+  stop("Input must be a matrix, SpatRaster, or legacy RasterLayer")
 }
 
-#' Extract XYZ coordinates from raster or matrix
+#' Extract XYZ coordinates from SpatRaster or matrix
 #'
 #' Simplifies raster or matrix data to XYZ coordinate format.
+#' Accepts `SpatRaster` (terra), legacy `Raster*` objects, or a plain matrix.
 #'
-#' @param x A RasterLayer or matrix object
+#' @param x A SpatRaster, legacy RasterLayer, or matrix object
 #' @return A data frame with x, y, z coordinates
 #' @export
 slope_xyz_simple <- function(x) {
-  if (inherits(x, "Raster")) {
-    xy <- raster::xyFromCell(x, 1:raster::ncell(x))
-    return(data.frame(x = xy[, 1], y = xy[, 2], z = raster::getValues(x)))
+  if (methods::is(x, "Raster")) {
+    message("Converting legacy Raster* object to SpatRaster. Consider using terra::rast() directly.")
+    x <- terra::rast(x)
+  }
+  if (methods::is(x, "SpatRaster")) {
+    df <- terra::as.data.frame(x, xy = TRUE)
+    names(df) <- c("x", "y", "z")
+    return(df)
   }
   if (is.matrix(x)) {
     df <- as.data.frame(as.table(x))
     names(df) <- c("y", "x", "z")
     return(df)
   }
-  stop("Input must be a RasterLayer or matrix")
+  stop("Input must be a SpatRaster, legacy RasterLayer, or matrix")
 }

R/slopes.R

@@ -154,23 +154,26 @@ slope_matrices <- function(m_xyz_split, fun = slope_matrix_weighted, ...) {
 #' Calculates slope gradients for routes using digital elevation model (DEM) raster data.
 #'
 #' @param routes An sf object containing linestring geometries
-#' @param dem A raster object containing elevation data
+#' @param dem A SpatRaster object (terra package) containing elevation data
 #' @param lonlat Logical, whether coordinates are longitude/latitude (default: auto-detected)
 #' @param method Method for raster extraction (default: "bilinear")
 #' @param fun Function for slope calculation (default: slope_matrix_weighted)
-#' @param terra Logical, whether to use terra package (default: auto-detected)
+#' @param terra Deprecated. Ignored; terra is always used.
 #' @param directed Logical, whether to calculate directed slopes (default: FALSE)
 #' @return Numeric vector of slope values
 #' @export
 slope_raster <- function(routes, dem, lonlat = sf::st_is_longlat(routes),
                          method = "bilinear", fun = slope_matrix_weighted,
-                         terra = has_terra() && methods::is(dem, "SpatRaster"),
+                         terra = NULL,
                          directed = FALSE) {
+  if (!is.null(terra)) {
+    .Deprecated(msg = "The 'terra' argument is deprecated and ignored. terra is always used.")
+  }
   if (is.na(lonlat)) stop("CRS of routes not known. Set CRS with sf::st_crs(routes) = 4326")
   stop_is_not_linestring(routes)
   routes <- sf::st_geometry(routes)
   m <- sf::st_coordinates(routes)
-  z <- elevation_extract(m, dem, method = method, terra = terra)
+  z <- elevation_extract(m, dem, method = method)
   m_xyz_df <- data.frame(x = m[, "X"], y = m[, "Y"], z = z, L1 = m[, "L1"])
   slope_xyz(m_xyz_df, fun = fun, lonlat = lonlat, directed = directed)
 }
@@ -202,36 +205,45 @@ slope_xyz <- function(route_xyz, fun = slope_matrix_weighted, lonlat = TRUE, dir
 #' Extract elevation values from coordinates
 #'
 #' Extracts elevation values from a DEM raster at specified coordinate locations.
+#' Accepts both `SpatRaster` (terra) and legacy `Raster*` (raster) objects;
+#' legacy objects are automatically converted to `SpatRaster`.
 #'
 #' @param m Matrix or sf object with coordinates
-#' @param dem A raster object containing elevation data
+#' @param dem A SpatRaster (or legacy RasterLayer) containing elevation data
 #' @param method Method for raster extraction (default: "bilinear")
-#' @param terra Logical, whether to use terra package (default: auto-detected)
+#' @param terra Deprecated. Ignored; terra is always used.
 #' @return Numeric vector of elevation values
 #' @export
-elevation_extract <- function(m, dem, method = "bilinear", terra = has_terra() && methods::is(dem, "SpatRaster")) {
+elevation_extract <- function(m, dem, method = "bilinear", terra = NULL) {
+  if (!is.null(terra)) {
+    .Deprecated(msg = "The 'terra' argument is deprecated and ignored. terra is always used.")
+  }
   if (any(grepl(pattern = "sf", class(m)))) m <- sf::st_coordinates(m)
-  if (terra) {
-    terra::extract(dem, m[, 1:2], method = method)[[1]]
-  } else {
-    raster::extract(dem, m[, 1:2], method = method)
+  if (!methods::is(dem, "SpatRaster")) {
+    if (requireNamespace("terra", quietly = TRUE)) {
+      message("Converting legacy Raster* object to SpatRaster. Consider using terra::rast() directly.")
+      dem <- terra::rast(dem)
+    } else {
+      stop("terra package is required. Install it with: install.packages('terra')")
+    }
   }
+  terra::extract(dem, m[, 1:2], method = method)[[1]]
 }
 
 #' Add elevation data to route linestrings
 #'
 #' Adds elevation (Z) coordinates to linestring geometries using DEM data.
 #'
 #' @param routes An sf object containing linestring geometries
-#' @param dem A raster object containing elevation data (default: NULL for automatic download)
+#' @param dem A SpatRaster object containing elevation data (default: NULL for automatic download)
 #' @param method Method for raster extraction (default: "bilinear")
-#' @param terra Logical, whether to use terra package (default: auto-detected)
+#' @param terra Deprecated. Ignored; terra is always used.
 #' @return An sf object with XYZ linestring geometries
 #' @export
 #' @examples
 #' library(sf)
 #' routes = lisbon_road_network[204, ]
-#' dem = dem_lisbon_raster
+#' dem = dem_lisbon()
 #' (r3d = elevation_add(routes, dem))
 #' st_z_range(routes)
 #' st_z_range(r3d)
@@ -244,20 +256,23 @@ elevation_extract <- function(m, dem, method = "bilinear", terra = has_terra() &
 #'   plot_slope(r3d_get)
 #' }
 #' }
-elevation_add <- function(routes, dem = NULL, method = "bilinear", terra = has_terra() && methods::is(dem, "SpatRaster")) {
+elevation_add <- function(routes, dem = NULL, method = "bilinear", terra = NULL) {
+  if (!is.null(terra)) {
+    .Deprecated(msg = "The 'terra' argument is deprecated and ignored. terra is always used.")
+  }
   stopifnotsf(routes)
   if (is.null(dem)) {
-    dem <- elevation_get(routes)  # Example will be \donttest{} in Rd
+    dem <- elevation_get(routes)  # returns SpatRaster
     r_original <- routes
-    routes <- sf::st_transform(routes, raster::crs(dem))
+    routes <- sf::st_transform(routes, terra::crs(dem))
     suppressWarnings({sf::st_crs(routes) <- sf::st_crs(r_original)})
     m <- sf::st_coordinates(routes)
     mo <- sf::st_coordinates(r_original)
-    z <- as.numeric(elevation_extract(m, dem, method = method, terra = terra))
+    z <- as.numeric(elevation_extract(m, dem, method = method))
     m_xyz <- cbind(mo[, 1:2], z)
   } else {
     m <- sf::st_coordinates(routes)
-    z <- as.numeric(elevation_extract(m, dem, method = method, terra = terra))
+    z <- as.numeric(elevation_extract(m, dem, method = method))
     m_xyz <- cbind(m[, 1:2], z)
   }
   n <- nrow(routes)

README.Rmd

@@ -25,7 +25,7 @@ knitr::opts_chunk$set(
 The **slopes** R package calculates the slope (longitudinal steepness, also known as gradient) of roads, rivers and other linear (simple) features, based on two main inputs:
 
 - [vector](https://r.geocompx.org/spatial-class.html) linestring geometries defined by classes in the [`sf`](https://r-spatial.github.io/sf/) package
-- [raster](https://r.geocompx.org/spatial-class.html) objects with pixel values reporting average height, commonly known as digital elevation model (**DEM**) datasets, defined by classes in the [`raster`](https://cran.r-project.org/package=raster) or more recent [`terra`](https://rspatial.org/terra) packages
+- [raster](https://r.geocompx.org/spatial-class.html) objects with pixel values reporting average height, commonly known as digital elevation model (**DEM**) datasets, defined by classes in the [`terra`](https://rspatial.org/terra) package (`SpatRaster`)
 
 Data on slopes are useful in many fields of research, including [hydrology](https://en.wikipedia.org/wiki/Stream_gradient), natural hazards (including [flooding](https://response.reliefweb.int/afghanistan) and [landslide risk management](https://assets.publishing.service.gov.uk/media/57a08d0740f0b652dd0016f4/R7815-ADD017_col.pdf)), recreational and competitive sports such as [cycling](https://theclimbingcyclist.com/gradients-and-cycling-an-introduction/), [hiking](https://trailism.com/trail-grades/), and [skiing](https://www.snowplaza.co.uk/blog/16682-skiing-steeps-what-does-gradient-mean-ski-piste/).
 Slopes are also also important in some branches of [transport and emissions modelling](https://doi.org/10.1016/j.trpro.2016.05.258) and [ecology](https://doi.org/10.1016/j.ncon.2016.10.001).
@@ -119,7 +119,7 @@ With the default argument `dem = NULL`, the function downloads the necessary ele
 You can also this use a local DEM (`dem = ...`), as shown in the example below:
 
 ```{r}
-sf_linestring_xyz_local = elevation_add(sf_linestring, dem = dem_lisbon_raster)
+sf_linestring_xyz_local = elevation_add(sf_linestring, dem = dem_lisbon())
 ```
 
 In both cases you can obtain the average gradient of the linestring with `slope_xyz()` and plot the elevation profile with `plot_slope()` as follows:

cran-comments.md

@@ -1,15 +1,26 @@
-Updated with DOI not journal's URL.
+# slopes 1.0.2 — CRAN resubmission after archival
 
-Removed the CRAN-SUBMISSIONS file.
+## Summary of changes
 
-Updated references based on feedback from manual CRAN checks.
+The package was archived on 2026-05-24 due to a CRAN check failure (#72).
+This submission fixes that issue and also resolves the long-standing issue #60
+(migrate from the deprecated `raster` package to `terra`).
 
-We have updated the URLs to comply with CRAN feedback
+### Key changes:
+- **Migrated from `raster` to `terra`** (closes #60): `raster` is no longer
+  developed and was removed from `Imports`. `terra` is now the sole raster
+  dependency.
+- **Fixed CRAN `--run-donttest` failure** (closes #72): The
+  `elevation_add()` example that triggered `ceramic`/Mapbox downloads is now
+  wrapped in `\dontrun{}` instead of `\donttest{}`.
+- The bundled DEM dataset has been renamed from `dem_lisbon_raster` (a
+  `RasterLayer`) to `dem_lisbon()` (a function returning a `SpatRaster`).
+  terra rasters cannot be serialised to `.rda`; shipping as a `.tif` in
+  `inst/` and exposing via an accessor function is the recommended pattern.
 
-Exported `plot_dz()` to avoid using ::: in examples
+## R CMD check results (local, --as-cran)
 
-## R CMD check results
+0 errors | 0 warnings | 0 notes
 
-0 errors | 0 warnings | 1 note
-
-* This is a new release.
+Tested on:
+- Linux (Ubuntu 24.04), R 4.6.x