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