scale_linetype_discrete, default to na.value='blank'

Fixes #711

Author: wch

R/scale-linetype.r

@@ -5,6 +5,7 @@
 #' values.
 #'
 #' @inheritParams scale_x_discrete
+#' @param na.value The linetype to use for \code{NA} values.
 #' @rdname scale_linetype
 #' @export
 #' @examples
@@ -19,8 +20,9 @@
 #' qplot(date, value, data=ecm, geom="line", colour=variable)
 #' 
 #' # See scale_manual for more flexibility
-scale_linetype <- function(...) {
-  discrete_scale("linetype", "linetype_d", linetype_pal(), ...)
+scale_linetype <- function(..., na.value = "blank") {
+  discrete_scale("linetype", "linetype_d", linetype_pal(),
+    na.value = na.value, ...)
 }
 
 #' @rdname scale_linetype

man/scale_linetype.Rd

@@ -4,13 +4,16 @@
 \alias{scale_linetype_discrete}
 \title{Scale for line patterns.}
 \usage{
-  scale_linetype(...)
+  scale_linetype(..., na.value = "blank")
 
   scale_linetype_continuous(...)
 
-  scale_linetype_discrete(...)
+  scale_linetype_discrete(..., na.value = "blank")
 }
 \arguments{
+  \item{na.value}{The linetype to use for \code{NA}
+  values.}
+
   \item{...}{common discrete scale parameters: \code{name},
   \code{breaks}, \code{labels}, \code{na.value},
   \code{limits} and \code{guide}.  See