address comment from @bart1

Author: edzer

R/sf.R

@@ -44,14 +44,19 @@ st_as_sf.data.frame = function(x, ..., agr = NA_agr_, coords, wkt,
 		else
 			x$geometry = st_as_sfc(as.character(x[[wkt]]))
 	} else if (! missing(coords)) {
-		cc = as.data.frame(lapply(x[coords], as.numeric))
+		cc = if (length(coords) == 1) {
+				stopifnot(is.matrix(x[[coords]]), is.numeric(x[[coords]]))
+				x[[coords]]
+			} else {
+				if (length(coords) == 2)
+					dim = "XY"
+				stopifnot(length(coords) == nchar(dim), dim %in% c("XY", "XYZ", "XYZM", "XYM"))
+				as.data.frame(lapply(x[coords], as.numeric))
+			}
 		if (na.fail && anyNA(cc))
 			stop("missing values in coordinates not allowed")
 		# classdim = getClassDim(rep(0, length(coords)), length(coords), dim, "POINT")
 		# x$geometry = structure( points_rcpp(attr(x, "points"), dim),
-		if (length(coords) == 2)
-			dim = "XY"
-		stopifnot(length(coords) == nchar(dim), dim %in% c("XY", "XYZ", "XYZM", "XYM"))
 		points = as.matrix(cc)
 		dimnames(points) = NULL
 		x$geometry = structure(vector("list", length = nrow(cc)),

R/sfc.R

@@ -162,12 +162,24 @@ st_sfc = function(..., crs = NA_crs_, precision = 0.0, check_ring_dir = FALSE, d
 
 
 #' @export
-#"[<-.sfc" = function (x, i, j, value) {
 "[<-.sfc" = function (x, i, value) {
-	if (is.null(value) || inherits(value, "sfg"))
+	if (is.null(value) || inherits(value, "sfg")) {
+		is_points = inherits(value, "POINT")
 		value = list(value)
+	} else
+		is_points = inherits(value, "sfc_POINT")
+	if (inherits(x, "sfc_POINT") && !is.null(attr(x, "points"))) {
+		if (is_points) {
+			repl = if (!is.null(pts <- attr(value, "points")))
+					pts
+				else
+					do.call(rbind, value)
+			attr(x, "points")[i, ] = repl
+			return(structure(x, n_empty = sum(is.na(attr(x, "points")[,1])))) # RETURNS
+		} else
+			x = x[] # realize
+	} 
 	x = unclass(x) # becomes a list, but keeps attributes
-
 	ret = st_sfc(NextMethod(), recompute_bbox = TRUE)
 	structure(ret, n_empty = sum(sfc_is_empty(ret)))
 }

R/tidyverse.R

@@ -52,8 +52,13 @@ group_split.sf <- function(.tbl, ..., .keep = TRUE) {
 #' }
 filter.sf <- function(.data, ..., .dots) {
 	agr = st_agr(.data)
+	g = st_geometry(.data)
 	class(.data) <- setdiff(class(.data), "sf")
-	.re_sf(NextMethod(), sf_column_name = attr(.data, "sf_column"), agr)
+	if (inherits(g, "sfc_POINT") && !is.null(pts <- attr(g, "points"))) {
+		.data[[ attr(.data, "sf_column") ]] = pts
+		st_as_sf(NextMethod(), coords = attr(.data, "sf_column"), agr = agr, remove = FALSE) # FIXME: doesn't handle tibble?
+	} else
+		.re_sf(NextMethod(), sf_column_name = attr(.data, "sf_column"), agr)
 }
 
 #' @name tidyverse