How can I rewrite this code as to ommit the for loop?

I'm writting a script for root (of plants) analysis. I work with quite large datasets (1000*1000*1000 pixels) and therefor I would like to optimalize the processing speed of the script. Right now I am using a for loop in order to assign a value of 1 to certain points in the volume with the rest being 0. My script looks as follows

 V2 = zeros(dimx,dimy,dimz); 
for x = 1:dimx
    for y = 1:dimy
        for z = 1:dimz
            if labda3(x,y,z) > 0 ;
                V2(x,y,z) = 0;
            elseif labda2(x,y,z) > 0 ;
                V2(x,y,z) = 0;
            else V2(x,y,z) = 1;                 
            end
        end
    end
end

Since Matlab is not very fast when using for loops I assumed that there is a faster way of doing this, however I cannot think of any myself. Can anyone help me with this?

Answer 1

[Star Strider]

See if this does what you want:

labda2 = randn(5, 5, 2)                         % Create Data
labda3 = randn(5, 5, 2)                         % Create Data

V2 = ones(size(labda2));
V2((labda2>0) | (labda3>0)) = 0

If it does what you want with the test data, it should work with your larger matrix.

[charles]

Thx! This does exactly what I want!

[Star Strider]

As always, my pleasure!