Connecting like numbers in a matrix

Suppose I have a matrix of the following data:

 data = [6, 5, 3, 0, 0, 1; ...
         0, 0, 0, 0, 0, 2; ...
         0, 0, 0, 0, 0, 4; ...
         0, 0, 0, 0, 0, 0; ...
         6, 0, 0, 0, 0, 0; ...
         5, 0, 4, 0, 0, 0]

What I would like to do is find the like entries that I can connect directly to by remaining on the edges of the matrix. So for instance, after applying this function I should get

 newdata = [6, 5, 3, 0, 0, 1; ...
            6, 0, 0, 0, 0, 2; ...
            6, 0, 0, 0, 0, 4; ...
            6, 0, 0, 0, 0, 4; ...
            6, 0, 0, 0, 0, 4; ...
            5, 0, 4, 4, 4, 4]

[Cedric]

Look at what you get when you run the following:

 for ii = 1 : size(data,1)
    data(ii, end)
 end

now you could exploit this approach to follow "edges" of your matrix and maybe update its elements.

[Harold]

Ok, I will try this out. I will have to think about the structure some more since I will have to start at some nonzero value on an edge and work my way around until I reach another entry with the same value, whilst making sure any values I "pass" through are zero.