compare matrices with different dimension

Question

gianluca 2015-1-10

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https://ww2.mathworks.cn/matlabcentral/answers/169506-compare-matrices-with-different-dimension

评论： gianluca 2015-1-12

Hi,

A = [100123 1 1 50; 
     100123 1 2 53; 
     100123 1 3 55; 
     100456 2 1 78; 
     100456 2 2 75;
     100789 1 1 80]
B = [100123 1 56; 
     100456 2 76]

Comparing the 1st and 2nd columns of A and B, I've to compute the difference between each value in the 4th comlumn of A and the values in the 3th column of B.

In the case to compute (A - B), the expected result is a Matrix as

C = [100123 1 1 -6; 
     100123 1 2 -3; 
     100123 1 3 -1; 
     100456 2 1  2; 
     100456 2 2 -1]

Tnx for any suggestion

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Answer 1

Stephen23 2015-1-10

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https://ww2.mathworks.cn/matlabcentral/answers/169506-compare-matrices-with-different-dimension#answer_164523

编辑：Stephen23 2015-1-11

在 MATLAB Online 中打开

You could try this:

>> X = bsxfun(@eq,A(:,1).',B(:,1));
>> Y = bsxfun(@minus,A(:,4).',B(:,3));
>> Z = [A(any(X,1),1:3),Y(X)]
Z =
        100123           1           1          -6
        100123           1           2          -3
        100123           1           3          -1
        100456           2           1           2
        100456           2           2          -1

It returns only the rows of A for which the first element matches any first row element in B, and in the last column gives the difference of corresponding end elements of A and B.

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gianluca 2015-1-12

在 MATLAB Online 中打开

Thanks Stephen,

your code worked well. As my original data are a little different than the example I've posted, I've added to your code a further logical operation to select the data that have the same key (1st col) and the same number (2nd col). Finally the following code works well for my purpose:

X1 = bsxfun(@eq,A(:,1).',B(:,1));
X2 = bsxfun(@eq,A(:,2).',B(:,2));
X = X1.*X2;
X = logical(X);
Y = bsxfun(@minus,A(:,4).',B(:,3));
Z = [A(any(X,1),1:3),Y(X)];

Your advices have been very useful!

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Answer 2

Image Analyst 2015-1-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/169506-compare-matrices-with-different-dimension#answer_164522

在 MATLAB Online 中打开

Try this:

A = [100123 1 1 50; 
     100123 1 2 53; 
     100123 1 3 55; 
     100456 2 1 78; 
     100456 2 2 75;
     100789 1 1 80]
B = [100123 1 56; 
     100456 2 76]
[rowsA, colA] = size(A);
[rowsB, colB] = size(B);
B_rep = [repmat(B(1,:), [rowsA/rowsB, 1]); repmat(B(2,:), [rowsA/rowsB, 1])]
C = A; % Initialize
C(:, 4) = A(:, 4) - B_rep(:, 3)

However I get:

C =
    100123           1           1          -6
    100123           1           2          -3
    100123           1           3          -1
    100456           2           1           2
    100456           2           2          -1
    100789           1           1           4