fixes #2357

NEWS.md

@@ -1,5 +1,7 @@
 # version 1.0-17
 
+* when `dim` is not `XYZM`, `sf_as_sf.data.frame()` interprets a length 4 `coords` argument to specify the corners of a rectangular polygon; #2357
+
 * `st_interpolate_aw()` gains an `na.rm` argument, for removing features with `NA` attributes before interpolating; #830
 
 # version 1.0-16

R/sf.R

@@ -10,14 +10,16 @@ st_as_sf = function(x, ...) UseMethod("st_as_sf")
 #' @param agr character vector; see details section of \link{st_sf}
 #' @param coords in case of point data: names or numbers of the numeric columns holding coordinates
 #' @param wkt name or number of the character column that holds WKT encoded geometries
-#' @param dim passed on to \link{st_point} (only when argument coords is given)
+#' @param dim specify what 3- or 4-dimensional points reflect: passed on to \link{st_point} (only when argument coords is given)
 #' @param remove logical; when coords or wkt is given, remove these columns from data.frame?
 #' @param na.fail logical; if \code{TRUE}, raise an error if coordinates contain missing values
 #' @param sf_column_name character; name of the active list-column with simple feature geometries; in case
 #' there is more than one and \code{sf_column_name} is \code{NULL}, the first one is taken.
 #' @param ... passed on to \link{st_sf}, might included named arguments \code{crs} or \code{precision}
 #' @details setting argument \code{wkt} annihilates the use of argument \code{coords}. If \code{x} contains a column called "geometry", \code{coords} will result in overwriting of this column by the \link{sfc} geometry list-column.  Setting \code{wkt} will replace this column with the geometry list-column, unless \code{remove} is \code{FALSE}.
 #'
+#' If `coords` has length 4, and `dim` is not `XYZM`, the four columns are taken as the xmin, ymin, xmax, ymax corner coordinates of a rectangle, and polygons are returned.
+#'
 #' @examples
 #' pt1 = st_point(c(0,1))
 #' pt2 = st_point(c(1,1))
@@ -50,14 +52,19 @@ st_as_sf.data.frame = function(x, ..., agr = NA_agr_, coords, wkt,
 		# classdim = getClassDim(rep(0, length(coords)), length(coords), dim, "POINT")
 		if (is.null(sf_column_name))
 			sf_column_name = "geometry"
-		x[[sf_column_name]] = structure( points_rcpp(as.matrix(cc), dim),
-			n_empty = 0L, precision = 0, crs = NA_crs_,
-			bbox = structure(
-				c(xmin = min(cc[[1]], na.rm = TRUE),
-				ymin = min(cc[[2]], na.rm = TRUE),
-				xmax = max(cc[[1]], na.rm = TRUE),
-				ymax = max(cc[[2]], na.rm = TRUE)), class = "bbox"),
-			class =  c("sfc_POINT", "sfc" ), names = NULL)
+		x[[sf_column_name]] = if (nchar(dim) < 4 && ncol(cc) == 4) { # create POLYGONs:
+				fn = function(x) st_as_sfc(st_bbox(c(xmin = x[[1]], ymin = x[[2]], xmax = x[[3]], ymax = x[[4]])))
+				do.call(c, apply(as.matrix(cc), 1, fn))
+			} else { # points:
+				structure( points_rcpp(as.matrix(cc), dim),
+				n_empty = 0L, precision = 0, crs = NA_crs_,
+				bbox = structure(
+					c(xmin = min(cc[[1]], na.rm = TRUE),
+					ymin = min(cc[[2]], na.rm = TRUE),
+					xmax = max(cc[[1]], na.rm = TRUE),
+					ymax = max(cc[[2]], na.rm = TRUE)), class = "bbox"),
+				class =  c("sfc_POINT", "sfc" ), names = NULL)
+			}
 
 		if (remove) {
 			if (is.character(coords))