On 5/10/2006 4:23 AM, Martin Maechler wrote: >>>>>> "Duncan" == Duncan Murdoch <[EMAIL PROTECTED]> >>>>>> on Tue, 09 May 2006 18:41:09 -0400 writes: > > Duncan> I've been thinking of adding the possibility of > Duncan> including "z" among the axes to be logged in image, > Duncan> contour, and persp. In the first two, it would only > Duncan> affect where the breaks were set if they are > Duncan> calculated automatically; it would have a bigger > Duncan> effect in persp. > > Duncan> For example, > > Duncan> image(x, y, z, log="z") > > Duncan> would set 12 colours evenly spaced on a log scale of > Duncan> the z values. (12 because that's the default). > > Duncan> We already support > > Duncan> image(x, y, z, log="x") > > Duncan> to scale the x axis (though there's a spurious > Duncan> warning; I'll fix that). > > Duncan> image(z, log="x") > > Duncan> fails because it tries to take a log of zero. > > Duncan> Does it seem like a good idea for these 3D functions > Duncan> to support log="z" the way 2D functions do? > > Yes, I think it's a good idea. > > You forgot to mention filled.contour() > which is image() + "color - legend" > For that one, it would be particularly useful to automatically > get a "evenly space in log-scale" one.
Thanks for pointing that out. This is a little tricky: I think filled.contour would want evenly spaced contours, but use the axTicks() version of pretty labels on the legend; but contour() would probably want the contours themselves to be at nice round values. It looks as though I'll need to think about adding a log=TRUE option to pretty(), to expose or duplicate the internal code that sets log axes. (axTicks is close, but I don't think it allows for automatic computation of axp[3]). Duncan > > Duncan> Duncan Murdoch > > Note that for things like the above, I have added > a simple function lseq() in package 'sfsmisc' -- which I have > contemplated moving to R. Maybe this could happen at the same > time and you could make use of it for the above. > > Martin > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
