Multiple loop doesn´t work with right values

Question

Mariana 2014-3-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/122024-multiple-loop-doesn-t-work-with-right-values

评论： Mariana 2014-3-19

Hello, I can´t figure out myself what is wrong with following nested loops:

index = 0;
for i = 1 : 2 : givenValue
    index = index + 1;
    j = i + 1;
    for k = 1 : givenValue/2        
        if sth_x(k) > sth_y(k)
        step(k) = sth_y(k) / sth_x(k);
        end
    end
    for id = 1 : givenValue/2
    values_x{index} = mat(i, 1) : mat(j, 1);
    values_y{index} = mat (i, 2) : step(id) : mat(j, 2);
end

In words, what I need is to generate two cell arrays (values_x and values_y) with one row and several columns, which contains all points (pixels - it is image analysis) between points (pixels) mat(i,1) and mat (j,1) with growing i and j. values_x are allways increased with 1, but values_y are supposed to be increased with step counted before. Problem I have is that cell array values_y is generated with step from the last iteration only. I need values_y{1,1} to be counted with step 1 and values_y{1,2} to be counted with step 2. Therefore values_x{1,1} and values_y{1,1} will be the same length.

I´m new to matlab and I know this might be simple. But I really don´t know what is wrong. I tried to change order of "for" and "if", tried to replace "id" with "k" but still nothing works.

Thank you for your advices very much.

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Answer 1

Nitin 2014-3-18

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https://ww2.mathworks.cn/matlabcentral/answers/122024-multiple-loop-doesn-t-work-with-right-values#answer_128914

You might need to initialize your cells first before saving to it.

a = cell(1, num);

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Nitin 2014-3-19

编辑：Nitin 2014-3-19

Hopefully this will help, I am not sure what you are trying to achieve though:

index = 0;
 givenValue = 10;
 step = 1:5;
 values_x = cell(1,10);
 values_y = cell(1,10);
 mat= randi(20,20,2);
for i = 1 : 2 : givenValue
    index = index + 1;
    j = i + 1;
    for k = 1 : givenValue/2        
        if 2 > 1
        display('So far so good')
        end
        for id = 1 : givenValue/2
            values_x{index} = mat(i, 1) : mat(j, 1);
            values_y{index} = mat (i, 2) : step(id) : mat(j, 2);
        end
    end
end

For example you can access the elements in the array using values_x{1}

Mariana 2014-3-19

Thanks for your try :) I copied code into my editor and tried to run it, but it didn´t make me understand how I could solve my problem :( Probably I can ´t explain my problem well via text online. But once again thank you

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