How to run R scripts on servers without X11

Question

I want to run R scripts and save the plots using png(). X11 is not supported on the Unix servers and I get the following error message:

Error in X11(paste("png::", filename, sep = ""), g$width, g$height, pointsize,  : 
  unable to start device PNG
Calls: png
In addition: Warning message:
In png("test.png", width = 900, height = 400) :
  unable to open connection to X11 display ''
Execution halted

Setting environment variables

Sys.setenv("DISPLAY"=":0.0")

or

Sys.setenv("DISPLAY"=":0")

in the R scripts didn't solve the problem.

This code example produces the error above:

library(ggplot2)
library(grid)

# Some data
df = data.frame(x = c(1.2,5,3,5.3,2,9,4,6,8,0), y = c(1.5,6,2.5,5.1,2.3,8.7,4.1,6,8,0))


# Base plot
p <- ggplot(df, aes(x,y)) + geom_point() +
   scale_x_continuous(limits = c(0, 8), expand = c(0,0)) +
   scale_y_continuous(limits = c(0, 8), expand = c(0,0)) +
   geom_smooth(method="lm", se=FALSE, formula=y~x, aes(colour="2"), show_guide=TRUE, fill=NA, size=1.2) +
   geom_vline(xintercept = 3) + geom_vline(xintercept = 7) +
   opts(plot.margin = unit(c(1,1,4,1), "lines"))

# Create the text Grobs
Text1 = textGrob("Part 1")
Text2 = textGrob("Part 2")
Text3 = textGrob("Part 3")

# Add the annotations
# Segment 1
p1 = p +
     annotation_custom(grob = linesGrob(), xmin = 0, xmax = 0, ymin = 
-1, ymax = -.75) +
     annotation_custom(grob = linesGrob(), xmin = 0, xmax = 3, ymin = 
-1, ymax = -1) +
     annotation_custom(grob = linesGrob(), xmin = 3, xmax = 3, ymin = 
-1, ymax = -.75) +
     annotation_custom(grob = Text1,  xmin = 0, xmax = 3, ymin = -1.25, 
ymax = -1.25)

# Segment 2
p1 = p1 +
     annotation_custom(grob = linesGrob(), xmin = 3, xmax = 7, ymin = 
-1, ymax = -1) +
     annotation_custom(grob = linesGrob(), xmin = 7, xmax = 7, ymin = 
-1, ymax = -.75) +
     annotation_custom(grob = Text2,   xmin = 3, xmax = 7, ymin = -1.25, 
ymax = -1.25)

# Segment 3
p1 = p1 +
     annotation_custom(grob = linesGrob(), xmin = 7, xmax = 8, ymin = 
-1, ymax = -1) +
     annotation_custom(grob = linesGrob(), xmin = 8, xmax = 8, ymin = 
-1, ymax = -.75) +
     annotation_custom(grob = Text3,  xmin = 7, xmax = 8, ymin = -1.25, 
ymax = -1.25)

png("test.png", width=900, height=400)

# Code to override clipping
gt <- ggplot_gtable(ggplot_build(p1))
gt$layout$clip[gt$layout$name=="panel"] <- "off"
grid.draw(gt)

dev.off()

The outcome of capabilities() is:

   jpeg      png     tiff    tcltk      X11     aqua http/ftp  sockets 
   FALSE    FALSE    FALSE     TRUE    FALSE    FALSE     TRUE     TRUE 

  libxml     fifo   cledit    iconv      NLS  profmem    cairo 
    TRUE     TRUE    FALSE     TRUE     TRUE    FALSE    FALSE

I am running the scripts via a sun grid engine.

Answer 1

if you are using R 3.0, try options(bitmapType='cairo') it worked for me

Answer 2

I answered this once before -- can cannot make a program which expects X11 to certainly forget about it, but you can use the virtual framebuffer to 'pretend' X11 is present.

So see this older SO question for details and an example.