Size mismatching using "find" command

Question

Matteo Migone 2022-8-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1778610-size-mismatching-using-find-command

评论： Voss 2022-8-14

Hi everyone,

I'm experiencing some issues using the find command inside a for loop. I have a 28x230 matrix (mean_GMT_min_mean_ref); of every row, I want to detect the first time the value 2, when present, is reached. That is the problem. Given this code

for i=1:length(FileList)
    y(i,1) = find((floor(mean_GMT_min_mean_ref(i,:))==2),1,'first');
    value_2(i,1) = mean_GMT_min_mean_ref(i,y(i));
    year_gwl_2(i,1) = x(y(i,1));
end

I get the error "Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-0." This because e.g. the second line of the matrix (and others) is made of values all < 2. I would just like, in the case that value isn't reached, to get a NaN in the column vector (y, value_2 and year_gwl_2 are all 28x1 vectors), instead of quitting the for loop with that annoying error.

Can anyone help me with this? Thanks in advance, Matteo

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Answer 1

Voss 2022-8-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1778610-size-mismatching-using-find-command#answer_1025835

for i=1:length(FileList)
    idx = find((floor(mean_GMT_min_mean_ref(i,:))==2),1,'first');
    if isempty(idx)
        y(i,1) = NaN;
        value_2(i,1) = NaN;
        year_gwl_2(i,1) = NaN;
    else
        y(i,1) = idx;
        value_2(i,1) = mean_GMT_min_mean_ref(i,y(i));
        year_gwl_2(i,1) = x(y(i,1));
    end
end