MATLAB: How to calculate differences in one column for specific pairs of rows (whose index are listed in another matrix)

aquivalent to vlookuppairs of rowsrow indeces

I've got a matrix A with two columns (mx2). Each row is a pair of row indices for another matrix B.

e.g. A = [1 3 ; 5 8 ; 11 15 ; … ] means that row 1 and 3 of matrix B are one pair.

I need to calculate the difference in column 11 of matrix B for all pairs of rows given in A. Any ideas?

Best Answer

"Deadahead" solution...
for i=1:size(A,1)
  D(i)=B(A(i,2),11)-B(A(i,1),11);
end

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MATLAB: Append a char vector to a subset of cells (whose indices are known) in cell array of character vectors

Your basic concept is correct, you just need to use indexing on the LHS as well as the RHS:

mycell(calidx_rng) = strcat('cal_', mycell(calidx_rng));
mycell(expidx_rng) = strcat('exp_', mycell(expidx_rng));
%     ^^^^^^^^^^^^ you need this!

Giving:

>> mycell{:}
ans = cal_start
ans = cal_t_001
ans = cal_t_002
ans = cal_t_003
ans = cal_t004
ans = cal_end
ans = exp_start
ans = exp_t_001
ans = exp_t_002
ans = exp_end

MATLAB: How to reduce the code (csvread, reshape, concatenate matrix)

I would do something like this.

fileList = {'bend/daria_bend_geo01.csv','bend/daria_bend_geo01.csv',<etc>}
numberFiles = numel(fileList);
bend = [];
for nf = 1:numberFiles
    thisFile{nf} = csvread(fileList{nf});
    thisFile{nf}=reshape(thisFile{nf},[],1);
    thisFile{nf}=thisFile{nf}(1:1568,:);
    bend = [bend; thisFile{nf}.'];
end

I don't have access to MATLAB -- or your files! -- right now, so I might not have the syntax just right. But I hope you get the idea.

Best Answer

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