error when using 'find' function

Hi

i actually want to find the first the first and last non zero row to avoid the edge effects and enforce them to zero for my analysis. But when i try running the code, i get this error - 'Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 0-by-1'. Here is the part of code that gives the error.

idxo1 = zeros(size(U_col,2),size(U_col,3));
idxo2 = zeros(size(U_col,2),size(U_col,3));
for j =1:size(U_col,3)-1
    for k = 1:size(U_col,2)-1
        idxo1(k,j) = find(EffectiveDivergence(:,k,j), 1, 'first');
        idxo2(k,j) = find(EffectiveDivergence(:,k,j), 1, 'last');
    end
end

5 and 6th line are giving the errors.

Thanks

Answer 1

[Rik]

If you store output of the find function to a temporary variable, you will notice that the error occurs when that temporary variable is empty.

If you can't guarantee a non-zero value can be found you need to think about a mitigation. Do you want to store a NaN? A zero?

[Sunil S Hosakoti]

Yes, I want to enforce the first and last non-zero row to 'zero (0)' to remove the edge effects or the artifact. I have attached images in transition (1st image and 18th image) which will tell you about the edge effects i'm mentioning about. Thanks

[Rik]

What is it exactly you want to remove? What do you want to measure? Those bright parts look much wider than a single pixel.

You could prevent the error in your original post with this line, but I doubt that will get you the result you want.

if ~any(EffectiveDivergence(:,k,j)),continue,end

[Sunil S Hosakoti]

I want to remove the encircled parts which is actually a transient efffect (basically an artifact). I am only interested in what happens beneath that tip. So in every frame i want to enforce that first non-zero occuring row to zero. I have about 200 frames for each experiment. If i don't, that single horizontal line in the first image develops into a huge band which is undesirable.

[Sunil S Hosakoti]

It was a problem due to the presence of NaN in the array. Got it sorted out.

Thanks a lot for your time and help.