How to transform a XYZ-Array into a XxY-Matrix with Z as values of each Mxy-Component and vice versa?

Hi, I have a table XYZ with three columns (xyz) as below:

1  1  1
1  2  2
1  3  3
2  1  4
2  2  5
2  3  6
3  1  7
3  2  8
3  3  9

and I want to transform it into a Mxy-Matrix with Z as value for each Mxy pair as follows:

1  4  7
2  5  8
3  6  9

On the other hand I may have directly the Matrix Mxy and would like to obtain the XYZ-table.

I already tried mesh, meshgrid, ndgrid, surf and etc... as documented, but nothing worked as I wished. It is possible that I did not understand yet how to use this commands.

I wonder if someone could tell me how to write the command to convert:

1) Table XYZ to Matrix Mxy with Z as values of each Mxy-pair 2) Matrix Mxy to Table XYZ

I thank you in advance for your help

Emerson

Answer 1

[Walter Roberson]

accumarray(XYZ(:,[2 1]), XYZ(:,3)]

[Emerson De Souza]

Thank you Walter, your suggestion works fine as below

xvector = 1:1:3;
yvector = 1:1:3;
numX = numel(xvector);  
numY = numel(yvector);
yvector = repmat(yvector(:),numX,1);
xvector = repmat(xvector   ,numY,1);
XY = [xvector(:) yvector];
Z=(1:1:length(XY))';

XYZ=[XY Z];
M=accumarray(XYZ(:,[2 1]), XYZ(:,3));

Now, if M is given, how do I obtain XYZ?

Thank you in advance

Emerson

[Walter Roberson]

[X,Y] = ind2sub(size(M), 1:numel(M));
XYZ = [X(:), Y(:), M(:)];

[Emerson De Souza]

Thank you Walter, your suggestions fixed my problem. Wish you a nice day

Emerson

[Ander Del Olmo Sanz]

I have the same problem, but in my case values are not whole number, since it is the measurement of a 3D part, but i want just to sabe the values of Z axis, so what can I do for rationa number with commas, like 5,5 or 7.8 in X and Y axis ?

Answer 2

[Chad Greene]

Thanks to Walter's excellent suggestion to use accumarray, I wrote an xyz2grid function to do this for GMT data.