error when using 'find' function

Question

Sunil S Hosakoti 2020-5-27

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https://ww2.mathworks.cn/matlabcentral/answers/535238-error-when-using-find-function

评论： Sunil S Hosakoti 2020-6-3

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

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Answer 1

Rik 2020-5-27

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https://ww2.mathworks.cn/matlabcentral/answers/535238-error-when-using-find-function#answer_440088

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?

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Sunil S Hosakoti 2020-5-28

编辑：Sunil S Hosakoti 2020-5-29

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 2020-6-3