Conditionally set pad in geom_freqpoly.

Fixes #1560

Author: hadley

R/geom-freqpoly.r

@@ -6,6 +6,12 @@ geom_freqpoly <- function(mapping = NULL, data = NULL,
                           na.rm = FALSE,
                           show.legend = NA,
                           inherit.aes = TRUE) {
+
+  params <- list(na.rm = na.rm, ...)
+  if (identical(stat, "bin")) {
+    params$pad <- TRUE
+  }
+
   layer(
     data = data,
     mapping = mapping,
@@ -14,10 +20,6 @@ geom_freqpoly <- function(mapping = NULL, data = NULL,
     position = position,
     show.legend = show.legend,
     inherit.aes = inherit.aes,
-    params = list(
-      na.rm = na.rm,
-      pad = TRUE,
-      ...
-    )
+    params = params
   )
 }

tests/testthat/test-geom-freqpoly.R

@@ -0,0 +1,12 @@
+context("freqpoly")
+
+test_that("can do frequency polygon with categorical x", {
+  df <- data.frame(x = rep(letters[1:3], 3:1))
+
+  p <- ggplot(df, aes(x)) + geom_freqpoly(stat = "count")
+  d <- layer_data(p)
+
+  expect_is(d$x, "integer")
+  expect_equal(d$x, 1:3)
+  expect_equal(d$y, 3:1)
+})