Use output of rsgeo for n_segments (#552)

DESCRIPTION

@@ -1,7 +1,7 @@
 Type: Package
 Package: stplanr
 Title: Sustainable Transport Planning
-Version: 1.1.2.9000
+Version: 1.2.0
 Authors@R: c(
     person("Robin", "Lovelace", , "[email protected]", role = c("aut", "cre"),
            comment = c(ORCID = "0000-0001-5679-6536")),

NEWS.md

@@ -1,7 +1,8 @@
-# stplanr (development version)
+# stplanr 1.2.0
 
-- `line_segment()` now will use `rsgeo::line_segmentize()` if available and only when the input geometry is not in geographic coordinates or does not have a CRS set as it uses euclidean distance
-  - `line_segment()` becomes an S3 generic which now has methods for `sf` and `sfc` class objects
+- `line_segment()` now will use `rsgeo::line_segmentize()` if available
+- `line_segment()` becomes an S3 generic which now has methods for `sf` and `sfc` class objects
+- `line_segment()` now works around [{rsgeo} issue](https://github.com/JosiahParry/rsgeo/issues/42) with `line_segmentize()` returning fewer segments than requested (#552)
 
 # stplanr 1.1.2  (2023-09)
 

R/linefuns.R

@@ -154,7 +154,8 @@ line_midpoint <- function(l, tolerance = NULL) {
 #' This function keeps the attributes.
 #' Note: results differ when `use_rsgeo` is `TRUE`:
 #' the `{rsgeo}` implementation is faster and more reliably
-#' keeps returned linestrings below a the `segment_length` value.
+#' keeps returned linestrings below a the `segment_length` value,
+#' but does not always return the number of segments requested.
 #'
 #' @inheritParams line2df
 #' @param segment_length The approximate length of segments in the output (overides n_segments if set)
@@ -354,6 +355,7 @@ line_segment_rsgeo <- function(l, n_segments) {
 
   # give them them CRS
   res <- sf::st_set_crs(res, crs)
+  n_segments <- length(res)
 
   # calculate the number of original geometries
   n_lines <- length(geo)
@@ -363,13 +365,12 @@ line_segment_rsgeo <- function(l, n_segments) {
   # index the original sf object
   res_tbl <- sf::st_drop_geometry(l)[ids, , drop = FALSE]
 
-  # assign the geometry column
-  nrow(res_tbl)
-
-  res_tbl[[attr(l, "sf_column")]] <- res
-
   # convert to sf and return
-  res_sf <- sf::st_as_sf(res_tbl)
+  res_sf <- sf::st_as_sf(
+    res_tbl,
+    geometry = res,
+    crs = crs    
+    )
   res_sf
 }
 

R/rnet_join.R

@@ -1,7 +1,7 @@
 #' Join route networks
 #'
-#' This is a spatial join function that is enables adding columns to a
-#' 'target' route network from a 'source' route
+#' Join function that adds columns to a
+#' 'target' route network `sf` object from a 'source' route
 #' network that contains the base geometry, e.g. from OSM
 #'
 #' The output is an sf object containing polygons representing
@@ -180,6 +180,10 @@ line_cast <- function(x) {
 }
 
 #' Merge route networks, keeping attributes with aggregating functions
+#' 
+#' This is a small wrapper around `rnet_join()`.
+#' In most cases we recommend using [`rnet_join()`] directly,
+#' as it gives more control over the results
 #'
 #' @inheritParams rnet_join
 #' @param sum_flows Should flows be summed? `TRUE` by default.
@@ -224,9 +228,6 @@ line_cast <- function(x) {
 #' # rnet_y = sf::read_sf("rnet_y_ed.geojson")
 #' # rnet_merged = rnet_merge(rnet_x, rnet_y, dist = 9, segment_length = 20, funs = funs)
 #' @return An sf object with the same geometry as `rnet_x`
-#'
-
-
 rnet_merge <- function(rnet_x, rnet_y, dist = 5, funs = NULL, sum_flows = TRUE, crs = geo_select_aeq(rnet_x), ...) {
 
   # handle_strings = function(strings) {

reprexes/test-rnet_join.R

@@ -69,3 +69,38 @@ funs = list(
     }
 
 rnet_merge(rnet_x, rnet_y, funs = funs, dist = 20)
+
+sfc_integer = sf::st_linestring(
+    cbind(
+        c(418938.4, 418949.7, 418961),
+        c(434303.2, 434280.1, 434257)
+    )
+) |>
+  sf::st_sfc() |>
+  sf::st_set_crs(27700)
+
+line_segment(sfc_integer, 10)
+
+sfc_no_integer = sf::st_linestring(
+    cbind(
+        c(418938.4, 418949.7, 418961.1),
+        c(434303.2, 434280.1, 434257)
+    )
+) |>
+  sf::st_sfc()
+
+
+rsgeo::line_segmentize(rsgeo::as_rsgeo(sfc_integer), n = 6) |>
+  sf::st_as_sfc() |>
+  sf::st_cast("LINESTRING") |>
+  length()
+
+rsgeo::line_segmentize(rsgeo::as_rsgeo(sfc_no_integer), n = 6) |>
+  sf::st_as_sfc() |>
+  sf::st_cast("LINESTRING") |>
+  length()
+
+library(stplanr)
+rnet_x = sf::read_sf("https://github.com/ropensci/stplanr/releases/download/v1.0.2/rnet_x_ed.geojson")
+rnet_y = sf::read_sf("https://github.com/ropensci/stplanr/releases/download/v1.0.2/rnet_y_ed.geojson")
+line_segment(rnet_y, 10)