[R] Patch for legend.position={left,top,bottom} in ggplot2

[Karsten Loesing]

Hi Hadley and everyone,

here's a patch for ggplot2 that fixes the behavior of
opts(legend.position={left,top,bottom}). If you try the following code
in an unmodified ggplot2

options(warn = -1)
suppressPackageStartupMessages(library("ggplot2"))
data <- data.frame(
    x = c(1, 2, 3, 4, 5, 6),
    y = c(2, 3, 4, 3, 4, 5),
    colour = c(TRUE, TRUE, TRUE, FALSE, FALSE, FALSE))
ggplot(data, aes(x = x, y = y, colour = colour)) +
    geom_line() + opts(title = "title", legend.position = "right")
ggplot(data, aes(x = x, y = y, colour = colour)) +
    geom_line() + opts(title = "title", legend.position = "left")
ggplot(data, aes(x = x, y = y, colour = colour)) +
    geom_line() + opts(title = "title", legend.position = "top")
ggplot(data, aes(x = x, y = y, colour = colour)) +
    geom_line() + opts(title = "title", legend.position = "bottom")

you'll see that plots 2 to 4 are broken.

I think I located the bug in surround_viewports() where the graphical
elements are placed into the grid. If we increment all rows and columns
of the graphical elements for positions "left", "top", and "bottom" by
1, those graphs look sane again. I assume that a new first row and
column were added at some point in the development, but only the
parameters for the default position "right" were adjusted. Here's the patch:


--- ggplot2-orig2	2010-06-07 13:14:35.000000000 +0200
+++ ggplot2	2010-06-07 15:22:33.000000000 +0200
@@ -7003,27 +7003,27 @@
     )
   } else if (position == "left") {
     viewports <- vpList(
-      vp("panels", 2, 3),
-      vp("legend_box", 2, 1),
-      vp("ylabel", 2, 2),
-      vp("xlabel", 3, 3),
-      vp("title", 1, 3)
+      vp("panels", 3, 4),
+      vp("legend_box", 3, 2),
+      vp("ylabel", 3, 3),
+      vp("xlabel", 4, 4),
+      vp("title", 2, 4)
     )
   } else if (position == "top") {
     viewports <- vpList(
-      vp("panels", 3, 2),
-      vp("legend_box", 2, 2),
-      vp("ylabel", 3, 1),
-      vp("xlabel", 4, 2),
-      vp("title", 1, 2)
+      vp("panels", 4, 3),
+      vp("legend_box", 3, 3),
+      vp("ylabel", 4, 2),
+      vp("xlabel", 5, 3),
+      vp("title", 2, 3)
     )
   } else if (position == "bottom") {
     viewports <- vpList(
-      vp("panels", 2, 2),
-      vp("legend_box", 4, 2),
-      vp("ylabel", 2, 1),
-      vp("xlabel", 3, 2),
-      vp("title", 1, 2)
+      vp("panels", 3, 3),
+      vp("legend_box", 5, 3),
+      vp("ylabel", 3, 2),
+      vp("xlabel", 4, 3),
+      vp("title", 2, 3)
     )
   } else {
     viewports <- vpList(


Best,
--Karsten