Add viridis palette

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: scales
-Version: 0.4.1.9000
+Version: 0.4.1.9001
 Authors@R: c(
     person("Hadley", "Wickham", , "hadley@rstudio.com", c("aut", "cre")),
     person("RStudio", role = "cph")
@@ -19,7 +19,8 @@ Imports:
     munsell (>= 0.2),
     labeling,
     methods,
-    Rcpp
+    Rcpp,
+    viridisLite
 LinkingTo: Rcpp
 Suggests:
     testthat (>= 0.8),

NAMESPACE

@@ -87,6 +87,7 @@ export(trans_format)
 export(trans_new)
 export(trans_range)
 export(unit_format)
+export(viridis_pal)
 export(wrap_format)
 export(zero_range)
 importFrom(Rcpp,evalCpp)

NEWS.md

@@ -1,4 +1,7 @@
-# scales 0.4.1.9000
+# scales 0.4.1.9001
+
+* Adds `viridis_pal()` for creating palettes with color maps from the
+  viridisLite package (@karawoo).
 
 # scales 0.4.1
 

R/pal-viridis.r

@@ -0,0 +1,15 @@
+#' Viridis palette
+#' 
+#' @inheritParams viridisLite::viridis
+#' @references \url{https://bids.github.io/colormap/}
+#' @export
+#' @examples
+#' show_col(viridis_pal()(10))
+#' show_col(viridis_pal(direction = -1)(6))
+#' show_col(viridis_pal(begin = 0.2, end = 0.8)(4))
+#' show_col(viridis_pal(option = "plasma")(6))
+viridis_pal <- function(alpha = 1, begin = 0, end = 1, direction = 1, option= "D") {
+  function(n) {
+    viridisLite::viridis(n, alpha, begin, end, direction, option)
+  }
+}