Confirmed after checking: aspect = diff(range(y))/diff(range(x)) in coutourplot looks like being the equivalent of asp = 1 (regarding practical result) in contour().
Essential for maps! Thanks a lot for the information and other most valuable hints. Patrick ----- Original Message ----- From: "Deepayan Sarkar" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; "Patrick Giraudoux" <[EMAIL PROTECTED]> Sent: Sunday, May 02, 2004 3:24 PM Subject: Re: [R] contourplot, xyplot, aspect ratio, mfrow > On Sunday 02 May 2004 03:30, Patrick Giraudoux wrote: > > Hi, > > > > I am gradually moving from the classical R plot functions to the > > library Lattice > > > > I have some questions about contourplot () and its arguments: > > > > 1/ I am working on geographical coordinates which makes necessary > > that the X (longitude) and Y (latitude) units be represented with the > > same distance on screen. This was obtained in the classical R plots > > with plot.default(x,y, asp=1,...) and then contour(..., add=T). When > > I try aspect=1 with contour plot, I get a square but not at all the > > aspect ratio I wish: 1 unit on X = one unit on Y = the same distance > > on screen. What goes wrong? > > Well, aspect works as documented, so nothing goes wrong. The behaviour > is just different from asp. You could try > > aspect = diff(range(y))/diff(range(x)) > > and if your x and y are factors, aspect = "xy" should help. Maybe there > should be a new option (perhaps aspect = "data") that should do this. > > > 2/ I would also be capable to project points and symbols on a > > contourplot (the equivalent of points() and symbols() after plot() > > and contour()), but can hardly guess from the help how to manage > > with. > > You need to use a custom panel function (see the section on 'panel' > in ?xyplot). There's no equivalent of symbols, unfortunately, but > see ?panel.abline and ?lpoints. > > > 3/ I would also appreciate to manage the equivalent of > > par(mfrow=c(2,2)) -or any other numbers of screens- and have a > > "Trellis" plot in each of the sub-screens. It seems that contourplot > > does not comply with and ignore the above parameters. Right or wrong? > > Right. > > > If so, which approach can solve this problem? > > See ?print.trellis. (Note that this also allows you to place trellis > plots inside grid viewports, which maybe overkill for your use, but > gives you more flexibility.) > > Deepayan ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html