CODEWITHSUNDEEP
matlabmatrix3d2dreshape
tehm0n
tehm0n

Reputation: 79

Reshape 2-D matrix with a specific format into a 3-D matrix (MATLAB)

I have a Cartesian 2-D matrix, A, that contains bins of dose values in three (X,Y,Z) dimensions;

Therefore, the total number of elements in A is nx*ny*nz=29622272. When reading a .dat-file, the data in matrix A are stored in the following format

A(1,1,1) A(2,1,1) A(3,1,1) A(4,1,1) A(5,1,1) A(6,1,1) A(7,1,1) A(8,1,1) A(9,1,1) A(10,1,1)

A(11,1,1) A(12,1,1) A(13,1,1) A(14,1,1) A(15,1,1) A(16,1,1) A(17,1,1) A(18,1,1) A(19,1,1) A(20,1,1)

…

A(503,1,1) A(504,1,1) A(505,1,1) A(506,1,1) A(507,1,1) A(508,1,1) A(509,1,1) A(510,1,1) A(511,1,1) A(512,1,1)

A(1,2,1) A(2,2,1) A(3,2,1) A(4,2,1) A(5,2,1) A(6,2,1) A(7,2,1) A(8,2,1) A(9,2,1) A(10,2,1)

A(11,2,1) A(12,2,1) A(13,2,1) A(14,2,1) A(15,2,1) A(16,2,1) A(17,2,1) A(18,2,1) A(19,2,1) A(20,2,1)

…

…

A(1,1,2) A(2,1,2) A(3,1,2) A(4,1,2) A(5,1,2) A(6,1,2) A(7,1,2) A(8,1,2) A(9,1,2) A(10,1,2)

…

A(511,512,113) A(512,512,113)

where the first index ix is assigned to the X coordinate, index iy is assigned to the Y coordinate and index iz is assigned to the Z coordinate in A(ix,iy,iz), and the first index runs faster than the second, and the second faster than the third. So when reading the matrix from the input file, A has the size [2962228 10] (the last row in the input file contains only two elements/columns).

I want to reshape this matrix into an equivalent Cartesian 3-D matrix, B(ix,iy,iz), of dimensions [nx ny nz] = [512 512 113] - is there an efficient way to do this? Also, 8 extra elements are appended in the last row when reading by fscanf() since A contains 10 elements per row - how do I not include these values when reshaping?

Many thanks in advance!!

Upvotes: 0

Views: 84

Answers (1)

Luis Mendo
Luis Mendo

Reputation: 112659

As discussed in comments, the following works:

B = A.'; % transpose to have the data in column-major order
B = B(1:end-8); % remove last values in linear order. Gives a column vector
result = reshape(B, [512 512 113]); % reshape to desired size

Upvotes: 1

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