MULTICURVE -> MULTILINESTRING cast; fixes #1194

NAMESPACE

@@ -140,6 +140,7 @@ S3method(st_cast,COMPOUNDCURVE)
 S3method(st_cast,CURVE)
 S3method(st_cast,GEOMETRYCOLLECTION)
 S3method(st_cast,LINESTRING)
+S3method(st_cast,MULTICURVE)
 S3method(st_cast,MULTILINESTRING)
 S3method(st_cast,MULTIPOINT)
 S3method(st_cast,MULTIPOLYGON)

NEWS.md

@@ -1,5 +1,7 @@
 # version 0.8-1
 
+* add `st_cast` method from `MULTICURVE` to `MULTILINESTRING`; #1194
+
 * `st_read` gains a parameter `wkt_filter` for spatially filtering the features to be read; #1192
 
 * `st_area()` and `st_length()` handle `+to_meter` argument in PROJ strings; #1170

R/cast_sfc.R

@@ -24,6 +24,7 @@ which_sfc_col = function(cls) {
 		MULTILINESTRING = 2,
 		POLYGON = 2,
 		MULTIPOLYGON = 3,
+		MULTICURVE = 3,
 		GEOMETRYCOLLECTION = 4,
 		MULTISURFACE = 4,
 		GEOMETRY = 5,

R/cast_sfg.R

@@ -218,12 +218,21 @@ st_cast.MULTISURFACE <- function(x, to, ...) {
 #' @name st_cast
 #' @export
 st_cast.COMPOUNDCURVE <- function(x, to, ...) {
-	if (! missing(to))
-		stop("to should be missing")
+	if (! missing(to) && to != "LINESTRING")
+		stop("to should be missing or LINESTRING")
 	CPL_compoundcurve_to_linear(structure(list(x), crs = NA_crs_, precision = 0.0, 
 		class = c("sfc_COMPOUNDCURVE", "sfc")))[[1]]
 }
 
+#' @name st_cast
+#' @export
+st_cast.MULTICURVE <- function(x, to, ...) {
+	if (! missing(to))
+		stop("to should be missing")
+	st_multilinestring(lapply(x, st_cast, to = "LINESTRING"))
+}
+
+
 #' @name st_cast
 #' @export
 st_cast.CURVE <- function(x, to, ...) { # nocov start

tests/cast.R

@@ -76,3 +76,9 @@ st_is(sfc, "POLYGON")
 st_is(sfc, "LINESTRING")
 st_is(st_sf(a = 1:2, sfc), "LINESTRING")
 st_is(sfc, c("POINT", "LINESTRING"))
+
+#1194:
+wkt <- "MULTICURVE (COMPOUNDCURVE (LINESTRING (-83.62333 35.55244, -83.62328 35.55232, -83.62323 35.55223, -83.62319 35.55216, -83.62312 35.55209, -83.6231 35.55207), CIRCULARSTRING (-83.6231 35.55207, -83.62307 35.55205, -83.62302 35.55204), LINESTRING (-83.62302 35.55204, -83.62299 35.55203, -83.62289 35.55198, -83.62281 35.55189, -83.62271 35.55182)))"
+g <- st_as_sfc(wkt)
+g <- st_sf(demo = "test", geom = g, crs = 4326)
+st_cast(g, "MULTILINESTRING")