This is possible using the cairoDevice package and RGtk2. Turning an R graphic into a raw vector of bytes:
library(cairoDevice) library(RGtk2) # create a pixmap and tell cairoDevice to draw to it pixmap <- gdkPixmapNew(w=500, h=500, depth=24) asCairoDevice(pixmap) # make a dummy plot plot(1:10) # convert the pixmap to a pixbuf plot_pixbuf <- gdkPixbufGetFromDrawable(NULL, pixmap, pixmap$getColormap(), 0, 0, 0, 0, 500, 500) # save the pixbuf to a raw vector buffer <- gdkPixbufSaveToBufferv(plot_pixbuf, "jpeg", character(0), character(0))$buffer ### Then you can send buffer to your database, or whatever. Replacing "jpeg" with "png" will probably produce png output. Michael On Nov 15, 2007 3:32 PM, Greg Snow <[EMAIL PROTECTED]> wrote: > You might try looking at the tkrplot package, it uses win.metafile and > captures the graphics device into a variable (which is then put into a > tk lable, but you could probably do something else with it). > > -- > Gregory (Greg) L. Snow Ph.D. > Statistical Data Center > Intermountain Healthcare > [EMAIL PROTECTED] > (801) 408-8111 > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Josh Tolley > > Sent: Thursday, November 15, 2007 2:08 PM > > To: r-help@r-project.org > > Subject: [R] Graphics device storable in a variable > > > > 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 > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
