Changing matrix into order pairs
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Hi, I have a matrix A=[1 2;1 3; 2 1;5 6;1 7;6 7],how I can change 'A' like this A=[(1 2);(1 3);(2 1);(5 6);(1 7);(6 7)] or like this A=[[1 2];[1 3];[2 1];[5 6];[1 7];[6 7]]. Thanks in advance
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Respuestas (3)
Guillaume
el 27 de Oct. de 2016
Neither of the two examples you show are remotely valid syntax in matlab since a matrix can only store a single scalar number per element, not matrices. So it's a bit difficult to answer you. Perhaps you want a cell array A = {[1 2];[1 3];[2 1];[5 6];[1 7];[6 7]} since cell arrays allow you to store matrices in each cell. In which case,
A = [1 2; 1 3; 2 1; 5 6; 1 7; 6 7]
newA = num2cell(A, 2)
But the bigger question is why? There's nothing that you can do with the cell array that you couldn't do with the original matrix (and probably more simply).
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Alexandra Harkai
el 27 de Oct. de 2016
This gives what you described as [[1 2];[1 3];[2 1];[5 6];[1 7];[6 7]]:
A=[1 2;1 3; 2 1;5 6;1 7;6 7];
B = mat2cell(A, ones(1,6),2);
But, it is not exactly clear what you mean by 'order pairs' or what you mean by [(1 2);(1 3);(2 1);(5 6);(1 7);(6 7)]. What is it you exactly want to do with these 'pairs'? For example, if you just want to access the n-th pair at a time, you can instead simply write
A(n,:)
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Guillaume
el 27 de Oct. de 2016
If you're going to use mat2cell to convert all the rows into a cell array (instead of the simpler num2cell), at least don't hardcode the sizes:
B = mat2cell(A, ones(1, size(A, 1)), size(A, 2));
so that it works with A of any size.
Amir Afshar
el 18 de Dic. de 2020
Editada: Amir Afshar
el 18 de Dic. de 2020
I think what you want is to have each entry in a vector be a pair of elements. To do that, you need to store each pair in a cell:
B = cell(numel(A,1),1);
for i = 1:length(A)
B(i) = {A(i,:)};
end
Then if
A = [1 2; 1 3; 2 1; 5 6; 1 7; 6 7];
Using the above snip of code:
B = 1×3 cell array
{1×2 double} {1×2 double} {1×2 double}
To access a specific element in B, though, you need to use {}.
B{1} returns [1,2]. B{1,2} still gives [1,2], so in order to get the second element from the first pair, you need to do something clever, like (using the dot product with a unit basis vector to extract the second element):
B{1}*[0;1]
This returns 2. As another example, B{4} returns [5,6], but B{4}*[1;0] gives 5:
B{4}*[1;0]
ans =
5
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