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matlabintersection
Hamid
Hamid

Reputation: 21

corresponding intersection of two rows without zero in matlab

I have a matrix(m*n). for every two rows, how I can find number of corresponding elements that are not zero. for example for following rows: r1=[1,3,0,4] , r2=[5,0,0,4] ,the answer is 2. because first and fourth elements in two rows are not zero. thanks

Upvotes: 2

Views: 67

Answers (2)

Luis Mendo
Luis Mendo

Reputation: 112699

I'm assuming you want to consider each block ot two rows; that is, first row with second, third with fourth etc.

Reshape the m×n input matrix A into an 2×m/2×n 3D array and then use all and sum along the appropriate dimensions:

result = sum(all(reshape(A, 2, [], size(A,2)), 1), 3);

As an example, for

A =
     0     2     0     0     0
     2     0     0     2     1
     1     0     1     2     2
     1     1     2     1     0
     1     1     1     1     2
     1     2     1     1     1

the result is

>> result = sum(all(reshape(A, 2, [], size(A,2)), 1), 3)
result =
     0     3     5

Upvotes: 0

rahnema1
rahnema1

Reputation: 15837

You can use matrix multiplication:

L = logical(m);     % convert the matrix to a logical matrix
result = L * L.';   % do matrix multiplication to compute number of corresponding elements

So the matrix element result(i,j) represents the number of corresponding elements between row i and row j.

Upvotes: 3

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