emptying each row of matrix of a in a loop then uses respective matrices produced from it to get a certain value

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JL 2019-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/477246-emptying-each-row-of-matrix-of-a-in-a-loop-then-uses-respective-matrices-produced-from-it-to-get-a-c

评论： JL 2019-8-27

采纳的回答： Matt J

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I have a matrix, a

a = [1 2;
3;
5; 
7;
8;];

and this matrix a, is emptied in each row per loop until the last one using this code from Matt J

a0=a;
for i=1:size(a,1)
    a=a0;
    a(i,:)=[],
end

which result in:

a = [1 3;
5; 
7;
8;];
a = [1 2;
5; 
7;
8;];
a = [1 2;
3;
7;
8;];
a = [1 2;
3;
5; 
8;];
a = [1 2;
3;
5; 
7;];

can I create another loop to calculate a certain value, w, from the results from each loop beginning with the orginal until the last one. After each loop answer value, w, is tabulated in matrix b

b = [w
    w
    w
    w
    w
    w]

there 6 values of w since we consider the orginal a

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JL 2019-8-22

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for i=1:size(a,1)
    a=a0;
    a(i,:)=[],
    % work with matrix a here
end

This code actually works but it doesnt save the values from this loop into another matrix

David Hill 2019-8-22

How about,

preallowcating array b = zeros(size(a,1)-1,2,size(a,1));

and having the following in the loop

b(:,:,i)=a;

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采纳的回答

Matt J 2019-8-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/477246-emptying-each-row-of-matrix-of-a-in-a-loop-then-uses-respective-matrices-produced-from-it-to-get-a-c#answer_388698

编辑：Matt J 2019-8-22

在 MATLAB Online 中打开

Why not as follows,

b=nan(size(a,1),1); %pre-allocate
for i=1:size(a,1)
    
    tmp=a;
    tmp(i,:)=[],
    
    b(i)=max(tmp(:))-min(tmp(:)); %example derived quantity
    
end