Merge pull request #459 from rstudio/joe/bugfix/empty-sf

Fix #452: Leaflet returns an error for empty "sf" "dataframe" objects

Author: jcheng5

DESCRIPTION

@@ -64,5 +64,5 @@ Suggests:
     RJSONIO,
     purrr,
     testthat
-RoxygenNote: 5.0.1
+RoxygenNote: 6.0.1
 LazyData: true

NAMESPACE

@@ -18,6 +18,7 @@ S3method(pointData,data.frame)
 S3method(pointData,default)
 S3method(pointData,matrix)
 S3method(pointData,sf)
+S3method(pointData,sfc_GEOMETRY)
 S3method(pointData,sfc_POINT)
 S3method(polygonData,Line)
 S3method(polygonData,Lines)

R/normalize-sf.R

@@ -9,12 +9,16 @@ metaData.sf <- function(obj) {
 
 #' @export
 pointData.sf <- function(obj) {
-  geometry <- obj[[attr(obj, "sf_column")]]
-  pointData(geometry)
+  pointData(sf::st_geometry(obj))
 }
 
 #' @export
 pointData.sfc_POINT <- function(obj) {
+  if (length(obj) == 0) {
+    # If a sfc_GEOMETRY is empty, just return nothing.
+    return(data.frame(lng = numeric(0), lat = numeric(0)))
+  }
+
   check_crs(obj)
 
   structure(
@@ -44,6 +48,21 @@ pointData.POINT <- function(obj) {
   )
 }
 
+#' @export
+pointData.sfc_GEOMETRY <- function(obj) {
+  if (length(obj) == 0) {
+    # If a sfc_GEOMETRY is empty, just return nothing.
+    data.frame(lng = numeric(0), lat = numeric(0))
+  } else if (all(vapply(obj, inherits, logical(1), "POINT"))) {
+    # If it's all POINT objects, then treat it as sfc_POINT.
+    pointData.sfc_POINT(obj)
+  } else {
+    # Otherwise, we don't know what to do. Let pointData.default throw an
+    # error.
+    NextMethod("pointData")
+  }
+}
+
 # polygonData -------------------------------------------------------------
 
 #' @export