Empty raster

[ben519]

When I try to do

ggplot(data.frame(x=c(1,2),y=c(1,2),z=c(1.5,1.5)),aes(x=x,y=y,color=z)) +
  geom_point()

I get the error "Error in grid.Call.graphics(L_raster, x$raster, x$x, x$y, x$width, x$height, : Empty raster"

I described this issue in a little more detail here http://stackoverflow.com/questions/23003527/weird-ggplot2-error-empty-raster

[rvernica]

Here is another case which triggers the same error:

R version 3.1.1 (2014-07-10)
Platform: x86_64-redhat-linux-gnu (64-bit)

library(ggplot2)
d <- data.frame(x=1, y=10, z=260)
ggplot(d, aes(x, y)) + geom_tile(aes(fill=z)) ## Works properly

d <- data.frame(x=1, y=10, z=261)
ggplot(d, aes(x, y)) + geom_tile(aes(fill=z))
Error in grid.Call.graphics(L_raster, x$raster, x$x, x$y, x$width, x$height,  : 
  Empty raster

[krlmlr]

According to the stack trace, this is probably a grid issue, and ggplot2 hardly can do anything about it:

 1: print(list(data = list(x = 1, y = 10, z = 261), layers = list(<envi
 2: print(list(data = list(x = 1, y = 10, z = 261), layers = list(<envi
 3: print.ggplot(list(data = list(x = 1, y = 10, z = 261), layers = lis
 4: grid.draw(gtable)
 5: grid.draw.gtable(gtable)
 6: grid.draw(gt)
 7: grid.draw.gTree(gt)
 8: recordGraphics(drawGTree(x), list(x = x), getNamespace("grid"))
 9: drawGTree(x)
10: grid.draw(x$children[[i]], recording = FALSE)
11: grid.draw.gTableChild(x$children[[i]], recording = FALSE)
12: NextMethod()
13: grid.draw.gtable(x$children[[i]], recording = FALSE)
14: grid.draw(gt)
15: grid.draw.gTableChild(gt)
16: NextMethod()
17: grid.draw.gTree(gt)
18: recordGraphics(drawGTree(x), list(x = x), getNamespace("grid"))
19: drawGTree(x)
20: grid.draw(x$children[[i]], recording = FALSE)
21: grid.draw.gTableChild(x$children[[i]], recording = FALSE)
22: NextMethod()
23: grid.draw.gtable(x$children[[i]], recording = FALSE)
24: grid.draw(gt)
25: grid.draw.gTableChild(gt)
26: NextMethod()
27: grid.draw.gTree(gt)
28: recordGraphics(drawGTree(x), list(x = x), getNamespace("grid"))
29: drawGTree(x)
30: grid.draw(x$children[[i]], recording = FALSE)
31: grid.draw.gTableChild(x$children[[i]], recording = FALSE)
32: NextMethod()
33: grid.draw.grob(x$children[[i]], recording = FALSE)
34: recordGraphics(drawGrob(x), list(x = x), getNamespace("grid"))
35: drawGrob(x)
36: drawDetails(x, recording = FALSE)
37: drawDetails.rastergrob(x, recording = FALSE)
38: grid.Call.graphics(L_raster, x$raster, x$x, x$y, x$width, x$height,

The function grid.Call.graphics is part of the grid namespace and simply calls a C implementation where the error probably occurs.

[krlmlr]

I stand corrected, it seems to be a ggplot2 issue after all. It looks like the color scale is not drawn correctly when the continuous scale uses only one color. The code below works:

d <- data.frame(x=1, y=10, z=260)
ggplot(d, aes(x, y)) + geom_tile(aes(fill=z)) + scale_fill_continuous(guide=FALSE)
d <- data.frame(x=1, y=10, z=261)
ggplot(d, aes(x, y)) + geom_tile(aes(fill=z)) + scale_fill_continuous(guide=FALSE)