You can use the grconvertX and/or grconvertY functions to help find the coordinates for your arrow (for plotting in the margin).
-- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.s...@imail.org 801.408.8111 > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r- > project.org] On Behalf Of Gavin Simpson > Sent: Tuesday, December 08, 2009 11:57 AM > To: Cable, Samuel B Civ USAF AFMC AFRL/RVBXI > Cc: r-help@r-project.org > Subject: Re: [R] arrow plots > > On Tue, 2009-12-08 at 13:42 -0500, Cable, Samuel B Civ USAF AFMC > AFRL/RVBXI wrote: > > Am doing some vector plots with the arrows() function. Works well. > But > > what I need to do is supply an arrow for scaling for the reader. I > need > > to plot an arrow of some known magnitude somewhere on the page > > (preferably outside the bounds of the plot, so that it can be seen > > clearly) with some text underneath it that says, for instance, "10 > > kg-m/sec". Any ideas? Thanks. > > You can plot outside the plotting region using the 'xpd' plotting > parameter: > > plot(1:10, 1:10) ## dummy plot > op <- par(xpd = TRUE) ## change clipping parameter & save defaults > arrows(9, 10.75, 10, 10.75, length = 0.1) ## draw reference arrow > text(9.5, 11, > labels = expression(10 ~ kg ~ m ~ sec^{"-1"})) ## add key > par(op) ## reset plotting parameter defaults > > You'll probably need to tweak the expression to get the units you > wanted. > > HTH > > G > -- > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > Dr. Gavin Simpson [t] +44 (0)20 7679 0522 > ECRC, UCL Geography, [f] +44 (0)20 7679 0565 > Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk > Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ > UK. WC1E 6BT. [w] http://www.freshwaters.org.uk > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > ______________________________________________ > 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.
