MATLAB: How to compute all the possible differences of the vectors in a matrix

matrixmatrix manipulation

Hi all,

I have a problem: given a matrix A such as

A = [1,2,3;

4,0,1;

2,3,5;

6,0,1];

is there any matlab function that returns a matrix with all the possible differences of rows? I mean: a matrix in which I have in the first row (1,2,3)-(4,0,1)=(-3,2,2), in the second row (1,2,3)-(2,3,5)=(-1,-1,-2) and so forth for all the rows? In other words I want to compute all the possible combinations of differences.

Thank you very much

Best Answer

result = A - permute(A, [3 2 1])

would return a size(A, 1) x size(A, 2) x size(A, 1) array where result(i, :, j) is the difference between A(i, :) and A(j, :)

Related Solutions

MATLAB: I have 6 numbers with repetation : 1,2,2,3,3,4. I want all possible combinations using any 4 of the numbers. How will I get that

You can still use nchoosek. Just use it to create indices into the vector rather than the vector itself:

v = [1,2,2,3,3,4];
Idx = nchoosek(1:size(v,2),4);
Out = v(Idx)
Out =
     1     2     2     3
     1     2     2     3
     1     2     2     4
     1     2     3     3
     1     2     3     4
     1     2     3     4
     1     2     3     3
     1     2     3     4
     1     2     3     4
     1     3     3     4
     2     2     3     3
     2     2     3     4
     2     2     3     4
     2     3     3     4
     2     3     3     4

Note the difference between ‘Idx’ and ‘’Out.

MATLAB: How to filter rows

Probably not the most efficient way, but this works

b = a(a(:,1)==1 & a(:,2) == 2 & a(:,3) == 3 & a(:,4) == 4,:)

Where a is the name of your matrix

Best Answer

Related Solutions

MATLAB: I have 6 numbers with repetation : 1,2,2,3,3,4. I want all possible combinations using any 4 of the numbers. How will I get that

MATLAB: How to filter rows

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