[R] Graphics device storable in a variable

[Gabor Grothendieck]

This works on Windows:

dev.control(displaylist="enable") # enable display list
plot(1:10)
myplot <- recordPlot() # load displaylist into variable

You can now store myplot and later fetch it and play it
back via

myplot
# or if not from the console
print(myplot)


On Nov 15, 2007 4:07 PM, Josh Tolley <eggyknap at gmail.com> wrote:
> I'm using R embedded in PostgreSQL (via PL/R), and would like to use
> it to create images. It works fine, except that I have to create every
> image in a file (owned by and only readable by the PostgreSQL server),
> and then use PostgreSQL to read from that file and return it to the
> client. It would be much nicer if I could plot images into an R
> variable (for instance, a matrix), and return that variable through
> the PostgreSQL client. Leaving aside the details of returning the data
> to PostgreSQL (which I realize are beyond the scope of this list), I
> envision R code along the lines of the following:
>
> # Create a png device, a handle to which is stored in myDevice
> > myDevice <- png.variable(height = 1280, width = 1024, bg = "white")
> # Plot some data into the current device
> > plot(myX, myY, col="red")
> # Finalize
> > dev.off()
> # Print out the contents of myDevice
> > myDevice
>
> ...and the data would print out just like any other matrix or class or
> whatever type myDevice actually is.
>
> So my question is does such a thing already exist? I know about
> piximage, but apparently I have to load image data from somewhere for
> it to work; I can't use plot(), etc. to create the piximage data. GDD
> would be a nice way to do it, because GD libraries are widely
> available for use with other languages I might use with PostgreSQL and
> PL/R (for instance, Perl would talk to PostgreSQL, call a PL/R
> function to use R to return an image, which Perl would then process
> further), but GDD requires temporary files as well, as far as I can
> see. Thanks for any help anyone can offer.
>
> -Josh / eggyknap
>
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