Merging matrices by comparison of values of several columns

I have 2 matrices of different size. Matrix A is 1000x18, while B has 950x10 size. The values in columns 2,3 and 4 can be common for both data sets. My goal is to merge them into single matrix consisting of shared values from columns 2:4 and corresponding to them values from column 5 in A and columns 6 and 8 from B. I tried to use this code, but it fails in generating combined matrix C:

[j] = intersect(out1(:,2:4),out2(:,2:4),'rows');
C = [out2(j,5) out1(j,[6 8])];

I would appreciate any help.

Answer 1

[Guillaume]

Nearly right

[~, whichArows, whichBrows] = intersect(out1(:, 2:4), out2(:, 2:4), 'rows');
C = [out2(whichBrows, 5), out1(whichArows, [6 8])];  %you may also want to include columns 2 to 4 

Note that if the keys (columns 2:4) are present more than once in either input you'll only get one of them in the output.

Another option is to convert your matrices to tables. Then you can perform an innerjoin, outerjoin or a plain join:

tout1 = array2table(out1); 
tout2 = array2table(out2);
joined = innerjoin(tout1, tout2, 'Keys', 2:4, 'LeftVariables', 5, 'RightVariables', [6 8]);

[Joanna Smietanska]

It works great, thank you very much