Getting values of 3D matrix via their (x,y) coordinates without using loop

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It might be trivial. I have a matrix say A which is 3D and consists of two slices ( A(:,:,1) and A(:,:,2)). I want to get a vector containing the values of a slice of this matrix (say the first slice) that correspond to the (x,y) coordinates I have in two row vectors, say: points_x and points_y i.e. I want to get the values:
A(points_x(1), points_y(1), 1), A(points_x(2), points_y(2), 1), ..., A(points_x(end), points_y(end), 1)
but I cannot figure out how to do this. I have tried:
A([points_x; points_y], 1)
but it returned a rectangular matrix not a vector. I don't want to use a for loop for the sake of code performance. Any ideas?
  2 comentarios
José-Luis
José-Luis el 29 de Jun. de 2016
If you want a vector, how are you going to distinguish between points?
Konstantinos
Konstantinos el 29 de Jun. de 2016
If the vector contains the values corresponding to the 2D coordinates in order which is:
A(points_x(1), points_y(1), 1), A(points_x(2), points_y(2), 1), ..., A(points_x(end), points_y(end), 1)
I am OK with that and I don't need to distringish them

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Respuesta aceptada

José-Luis
José-Luis el 29 de Jun. de 2016
A = rand(5,5,2);
x = (1:3);
y = (2:4);
your_result = cell2mat(arrayfun(@(x,y) reshape(A(x,y,:),1,[]),x,y,'uniformoutput',false))
  2 comentarios
Konstantinos
Konstantinos el 29 de Jun. de 2016
Thank you ver much. The odd indices correspond to the 1st slice while the even indices correspond to the 2nd slice.

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Más respuestas (1)

KSSV
KSSV el 29 de Jun. de 2016
why dont you go for interpolation? Interpolation would be the easiest one to get values at your desired points.

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