Problems with saving vectors to cell array

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Mariana 2014-3-8

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评论： Mariana 2014-3-8

Hello, newbie to Matlab here. I have a problem with saving vectors (which are not of the same length) to cell array. Let´s say I have a 2x8 matrix p and I access it´s cells via linear indices. I create vectors of pixels between p(1) : p(3) then p(5) : p (7) and p(9) : p(11). If I write this (e.g. vec = p(1) : p(3)) into command window I get the vector. What I try is to create these three (or more it depends) vectors and save them in cell array as follows:

rows = 0.5.*length(p);
k = 2.*length(p);
for i = 1 : 4 : k
    for j = 3 : 4 : k
        for m = 1 : rows
            p(i);
            p(j);
            M{m} = p(i) : p(j);
        end
    end
end

The problem is that the M-array created has 3 rows and every row contains the vector of same length (the last vector created, in my case p(9) : p(11)). What is wrong in my code that the output is this and not three rows containing three vectors as I desribed before?

I deal with this long time and finally I really dont know :( Thank you very much for your advices, Mari.

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the cyclist 2014-3-8

编辑：the cyclist 2014-3-8

Can you please give an example of the matrix p, such that the code is self-contained and illustrates the problem?

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Answer 1

the cyclist 2014-3-8

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/120694-problems-with-saving-vectors-to-cell-array#answer_127526

编辑：the cyclist 2014-3-8

在 MATLAB Online 中打开

I am not 100% clear on what you want to do, but here is a guess:

p = [1  2  3  4  5  6  7  8;
     9 10 11 12 13 14 15 16];
rows = 0.5.*length(p);
k = 2.*length(p);
rowCounter = 0;
for i = 1 : 4 : k
    rowCounter = rowCounter+1;
    j = i+2;
    p(i);
    p(j);
    M{rowCounter} = p(i) : p(j);
end

The main things that I have done are:

Introduced some fake p data
Removed the loop over j, because it seems that j is always determined by i, rather than being its own independent loop
Removed the loop over m, because again this is really just counting rows, which is effectively done already in the one loop

I think the important thing to realize (if I have understood your intent correctly), is that you really only have one loop -- the starting value of your index -- and everything keys off of that.

I expect I don't have this quite right, but I bet it is closer to what you wanted to do.

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Mariana 2014-3-8

You understood my question very well and you have helped me also :) Very thank you, it works! I´m sorry I´m not skilled enough for such a things but I still learn.

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