Shapes provided via strings instead of integers

NEWS.md

@@ -125,6 +125,9 @@ up correct aspect ratio, and draws a graticule.
   `panel_params` (#1311). These are parameters of the Coord that vary from
   panel to panel.
 
+* Shapes can now be provided using strings instead of integers (i.e.
+  `geom_point(shape = "diamond")`) (@daniel-barnett, #2075). 
+
 ## Minor bug fixes and improvements
 
 ### Facetting

R/geom-point.r

@@ -98,6 +98,14 @@ geom_point <- function(mapping = NULL, data = NULL,
                        na.rm = FALSE,
                        show.legend = NA,
                        inherit.aes = TRUE) {
+  dots <- list(...)
+  if (hasArg("shape")) {
+    # Numerics/Strings of length 1 should not be translated
+    if (is.character(dots$shape) && nchar(dots$shape[1]) > 1) {
+      dots$shape <- translate_shape_string(dots$shape)
+    }
+  }
+
   layer(
     data = data,
     mapping = mapping,
@@ -106,9 +114,9 @@ geom_point <- function(mapping = NULL, data = NULL,
     position = position,
     show.legend = show.legend,
     inherit.aes = inherit.aes,
-    params = list(
+    params = c(
       na.rm = na.rm,
-      ...
+      dots
     )
   )
 }
@@ -144,3 +152,47 @@ GeomPoint <- ggproto("GeomPoint", Geom,
 
   draw_key = draw_key_point
 )
+
+translate_shape_string <- function(shape_string) {
+  pch_table <- c(
+    "0" = "square open",
+    "1" = "circle open",
+    "2" = "triangle open",
+    "3" = "plus",
+    "4" = "cross",
+    "5" = "diamond open",
+    "6" = "triangle down open",
+    "7" = "square cross",
+    "8" = "asterisk",
+    "9" = "diamond plus",
+    "10" = "circle plus",
+    "11" = "star",
+    "12" = "square plus",
+    "13" = "circle cross",
+    "14" = "square triangle",
+    "15" = "square",
+    "16" = "circle small",
+    "17" = "triangle",
+    "18" = "diamond",
+    "19" = "circle",
+    "20" = "bullet",
+    "21" = "circle filled ",
+    "22" = "square filled",
+    "23" = "diamond filled",
+    "24" = "triangle filled",
+    "25" = "triangle down filled"
+  )
+
+  shape_match <- pmatch(shape_string, pch_table, duplicates.ok = TRUE)
+
+  if (any(is.na(shape_match))) {
+    bad_string <- shape_string[is.na(shape_match)]
+    collapsed_names <- paste0(bad_string, collapse = "', '")
+    stop(
+      "Invalid shape name: '", collapsed_names, "'", 
+      call. = FALSE
+    )
+  }
+
+  as.integer(names(pch_table[shape_match]))
+}

R/scale-manual.r

@@ -56,6 +56,12 @@ scale_size_manual <- function(..., values) {
 #' @rdname scale_manual
 #' @export
 scale_shape_manual <- function(..., values) {
+  if (is.character(values) && nchar(values[1]) > 1) {
+    orig_names <- names(values)
+    values <- translate_shape_string(values)
+    names(values) <- orig_names
+  }
+
   manual_scale("shape", values, ...)
 }