Plotting to a file in R

Question

I'm a complete newbie to R, and none of the introductions I've seen cover how to use R when all you've got is the command line and no windowing system. My data's on a server, and I'm working with it via ssh. In gnuplot, you can set your "display" to be a PNG file on disk. How do I plot something to a file on disk from R? R-2.9.1 on CentOS, if it matters. Thanks!

(Sorry if this is unusually basic, but I have the worst time Googling for quick answers with R. Cute name, impossible to search for.)

Answer 1

Just to expand on Gnoupi answer, you also need to close the connection to the device with dev.off if you want the plot to be written to file.

For instance

pdf("mygraph.pdf")
plot(x, y, "l")
dev.off()

Answer 2

Keep in mind that postscrpt(), pdf(), png(), and jpeg() have specific function parameters which can be used to customize the output.

For example:

postscript("filename.eps", horizontal=F, width=4, height=4, 
             paper="special", onefile=F)
plot(x)
dev.off()

check ?postscriptfor more information on the parameters that can be utilized.

Secondly, keep in mind that all commands that you want to be included in your saved plot should be executed prior to dev.off()

For example:

postscript("filename.eps", horizontal=F, width=4, height=4, 
             paper="special", onefile=F)
plot(x)    
text(5, 1, "This is a message for the aliens")
text(5, 0.5, "Pizza is tasty")
dev.off()

Another example:

regone <- glm(y ~ x1, data=mydata, family=...)
summary(regone)

postscript("filename.eps", horizontal=F, width=4, height=4, 
                 paper="special", onefile=F)
plot(x, y)
abline(regone)
dev.off()

Hope that helps.