How to save a plot as image on the disk?

Question

I plot a simple linear regression using R. I would like to save that image as PNG or JPEG, is it possible to do it automatically? (via code)

There are two different questions: First, I am already looking at the plot on my monitor and I would like to save it as is. Second, I have not yet generated the plot, but I would like to directly save it to disk when I execute my plotting code.

Answer 1

There are two closely-related questions, and an answer for each.

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1. An image will be generated in future in my script, how do I save it to disk?

To save a plot, you need to do the following:

1. Open a device, using png(), bmp(), pdf() or similar
2. Plot your model
3. Close the device using dev.off()

Some example code for saving the plot to a png file:

fit <- lm(some ~ model)

png(filename="your/file/location/name.png")
plot(fit)
dev.off()

This is described in the (combined) help page for the graphical formats ?png, ?bmp, ?jpeg and ?tiff as well as in the separate help page for ?pdf.

Note however that the image might look different on disk to the same plot directly plotted to your screen, for example if you have resized the on-screen window.

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Note that if your plot is made by either lattice or ggplot2 you have to explicitly print the plot. See this answer that explains this in more detail and also links to the R FAQ: ggplot's qplot does not execute on sourcing

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2. I'm currently looking at a plot on my screen and I want to copy it 'as-is' to disk.

dev.print(pdf, 'filename.pdf')

This should copy the image perfectly, respecting any resizing you have done to the interactive window. You can, as in the first part of this answer, replace pdf with other filetypes such as png.

Answer 2

If you want to keep seeing the plot in R, another option is to use dev.copy:

X11 ()
plot (x,y)

dev.copy(jpeg,filename="plot.jpg");
dev.off ();

If you reach a clutter of too many plot windows in R, use graphics.off() to close all of the plot windows.

Answer 3

If you use ggplot2 the preferred way of saving is to use ggsave. First you have to plot, after creating the plot you call ggsave:

ggplot(...)
ggsave("plot.png")

The format of the image is determined by the extension you choose for the filename. Additional parameters can be passed to ggsave, notably width, height, and dpi.

Answer 4

Like this

png('filename.png')
# make plot
dev.off()

or this

# sometimes plots do better in vector graphics
svg('filename.svg')
# make plot
dev.off()

or this

pdf('filename.pdf')
# make plot
dev.off()

And probably others too. They're all listed together in the help pages.

Answer 5

For the first question, I find dev.print to be the best when working interactively. First, you set up your plot visually and when you are happy with what you see, you can ask R to save the current plot to disk

dev.print(pdf, file="filename.pdf");

You can replace pdf with other formats such as png.

This will copy the image exactly as you see it on screen. The problem with dev.copy is that the image is often different and doesn't remember the window size and aspect ratio - it forces the plot to be square by default.

For the second question, (as others have already answered), you must direct the output to disk before you execute your plotting commands

pdf('filename.pdf')
plot( yourdata )
points (some_more_data)
dev.off() # to complete the writing process and return output to your monitor

Answer 6

If you use R Studio http://rstudio.org/ there is a special menu to save you plot as any format you like and at any resolution you choose

Answer 7

If you open a device using png(), bmp(), pdf() etc. as suggested by Andrie (the best answer), the windows with plots will not pop up open, just *.png, *bmp or *.pdf files will be created. This is convenient in massive calculations, since R can handle only limited number of graphic windows.

However, if you want to see the plots and also have them saved, call savePlot(filename, type) after the plots are drawn and the window containing them is active.

Answer 8

plotpath<- file.path(path, "PLOT_name",paste("plot_",file,".png",sep=""))

png(filename=plotpath)

plot(x,y, main= file)

dev.off()

Answer 9

To add to these answers, if you have an R script containing calls that generate plots to screen (the native device), then these can all be saved to a pdf file (the default device for a non-interactive shell) "Rplots.pdf" (the default name) by redirecting the script into R from the terminal (assuming you are running linux or OS X), e.g.:

R < myscript.R --no-save

This could be converted to jpg/png as necessary

Answer 10

In some cases one wants to both save and print a base r plot. I spent a bit of time and came up with this utility function:

x = 1:10

basesave = function(expr, filename, print=T) {
  #extension
  exten = stringr::str_match(filename, "\\.(\\w+)$")[, 2]

  switch(exten,
         png = {
           png(filename)
           eval(expr, envir = parent.frame())
           dev.off()
         },
         {stop("filetype not recognized")})


  #print?
  if (print) eval(expr, envir = parent.frame())

  invisible(NULL)
}

#plots, but doesn't save
plot(x)

#saves, but doesn't plot
png("test.png")
plot(x)
dev.off()

#both
basesave(quote(plot(x)), "test.png")

#works with pipe too
quote(plot(x)) %>% basesave("test.png")

Note that one must use quote, otherwise the plot(x) call is run in the global environment and NULL gets passed to basesave().

Answer 11

dev.copy(png,'path/pngFile.png')
plot(YData ~ XData, data = mydata)
dev.off()