issue #2505, hiding boxplot outliers (#2658)

* expand boxplot documentation; don't try to match strings of length 0
to shape names. closes #2505

* update documentation

Author: clauswilke

R/geom-boxplot.r

@@ -37,6 +37,13 @@
 #'
 #'   In the unlikely event you specify both US and UK spellings of colour, the
 #'   US spelling will take precedence.
+#'
+#'   Sometimes it can be useful to hide the outliers, for example when overlaying
+#'   the raw data points on top of the boxplot. Hiding the outliers can be achieved
+#'   by setting `outlier.shape = NA`. Importantly, this does not remove the outliers,
+#'   it only hides them, so the range calculated for the y-axis will be the
+#'   same with outliers shown and outliers hidden.
+#'
 #' @param notch If `FALSE` (default) make a standard box plot. If
 #'   `TRUE`, make a notched box plot. Notches are used to compare groups;
 #'   if the notches of two boxes do not overlap, this suggests that the medians

R/geom-point.r

@@ -146,7 +146,8 @@ GeomPoint <- ggproto("GeomPoint", Geom,
 )
 
 translate_shape_string <- function(shape_string) {
-  if (nchar(shape_string[1]) == 1) {
+  # strings of length 0 or 1 are interpreted as symbols by grid
+  if (nchar(shape_string[1]) <= 1) {
     return(shape_string)
   }