MATLAB: How to subtract columns for each row by using a for loop

for loopsubtract columns

Hi,

I have a matrix like this:

[1.011  1.004  1.054
1.008  0.998  1.042
0.984  0.988  1.024
1.026  1.006  1.016
1.000  0.996  0.977]

I would like to subtract each column for each row and store these results in a new matrix. How can I do this?

Thanks!

Best Answer

nk=nchoosek(1:size(x,2),2);
dx=zeros(size(x,1),size(nk,1));
for i=1:size(nk,1)
  dx=x(:,nk(i,2))-x(:,nk(i,1));
end

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MATLAB: Subsetting a rectengular matrix

What you asked for will not fit. There is only enough data for each block to have 131, with 9 left over that could be distributed

N = 39;
R = size(YourMatrix,1);
pos = floor(linspace(1,R,N+1));
pos(end) = R+1;
sizes = diff(pos);
subsets = mat2cell(YourMatrix, sizes, size(YourMatrix,2));

MATLAB: Problem Related to Scenario Generation.

The following will work for input matrices of width of 10 or less, due to the usage of dec2base to generate the various column combinations:

in = [100, 60, 20;, 50, 30, 10; 700, 500, 200];
assert(size(in, 2) <= 10, 'input matrix is too wide');
numperms = size(in, 2) ^ size(in, 1);
colselect = dec2base(0:numperms-1, size(in, 2)) - '0' + 1;
rowselect = repmat(1:size(in, 1), numperms, 1);
out = in(sub2ind(size(in), rowselect, colselect))

For larger matrices (but the number of permutations may be prohibitively high), it's possible to generate the combinations with ndgrid:

 colcombs = cell(1, size(in, 1));
 [colcombs{:}] = ndgrid(1:size(in, 2));
 colcombs = cellfun(@(c) c(:), colcombs, 'UniformOutput', false);
 colselect = [colcombs{:}];

Best Answer

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MATLAB: Subsetting a rectengular matrix

MATLAB: Problem Related to Scenario Generation.

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