[Rd] RFC: log='z' for image, contour, persp?
maechler at stat.math.ethz.ch
Wed May 10 10:23:15 CEST 2006
>>>>> "Duncan" == Duncan Murdoch <murdoch at stats.uwo.ca>
>>>>> 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.
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.
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