[R] "Over-coloring" facets on persp() plot

[Marc Chiarini (Tufts)]

Thanks Duncan (and David).  I couldn't get back to my computer until 
today.  I understand it pretty well now and I'm able to get what I need.

On a side note, I have had a hard time getting rgl to work.  For the 
moment, I have to compile without libpng and ftfonts, and when I load 
the package I get an error related to OpenGL (from memory, something 
like "no GLX extension found").  I'll write more as soon as I'm able.

Regards,
Marc Chiarini

Duncan Murdoch wrote:
> On 22/11/2009 1:07 AM, Marc Chiarini (Tufts) wrote:
>> Dear R Community:
>>
>> Recently, I have managed to plot some really useful graphs of my 
>> research data using persp().  I have even figured out how to overplot 
>> rectangular regions (corresponding to submatrices) with a different 
>> color.  This is accomplished by using par(new=T).  I am now searching 
>> for a way to "highlight" a set of (possibly non-contiguous) facets 
>> with a specific color, e.g., the facet between each set of four 
>> points whose values are all above a certain threshold.  An example 
>> would be coloring the raised corners of the classic sombrero (found 
>> in example(persp)) differently from the rest of the sombrero.  I feel 
>> like the last example in persp() is pointing me in the right 
>> direction, but I'm not quite getting it.  Any help is much appreciated.
>
> Think of the facets as an nx-1 by ny-1 matrix.  Pass the col arg by 
> creating a matrix of this shape.  (A vector version of the data in the 
> matrix would also be good enough.)
>
> If you pass something shorter, it will be recycled to that length.
>
> You could also use persp3d from the rgl package, but an important 
> difference is that it colours all nx by ny vertices, and interpolates 
> colours on the facets.  So you can't use the same colour matrix as in 
> persp.
>
> Duncan Murdoch