[R] 3D-plotting a 2D-matrix that contains z-values (3rd dimension)

[oliver]

On Thu, Jun 09, 2011 at 11:22:54AM +0200, Uwe Ligges wrote:
> Well,
> 
> persp(x, y, z) does exactly what you asked for: it plots tha matrix
> z along the values given by the vectors x and y.

But I don't have these vectors x and y, so I have to
create them just to call persp().
And persp also needs the values only to rise.

But if I have x and y, and I want to have only rising numbers for x and y,m
I need somehow to create those values, and expand.grid()
would not create value combinations that are only rising.
(Or did I miss an option for expand.grid, which does that?)

> If you need to calculate z values from x and y using some function
> foo, outer(x, y, foo) is typically your friend.

OK.

And what, if I want to generate the mathcing x- and y- values
for a matrix, that has x- and y implicitly, but I only have the
z-values inside the matrix?

So, my problem is the other way around.
I don't want to calc the z for my x-and y, I want to generate the x-
and y- values for my matrix of z-values.


Ciao,
   Oliver