RANDBLOCK 2.3

RANDBLOCK - randomize blocks of a matrixR = RANDBLOCK(M,S) randomizes the matrix M by dividing M into non-overlapping blocks of the size specified by S, and shuffling these blocks. M can be a N-D matrix.The number of elements in S should match the number of dimensions of M, or S can be a scalar specifying a S-by-S-by-S-by ... block size. S should contain positive integers. The size of M in any dimension should be an integer number of times the specified size of the block in that dimension (e.g., if size(M,1) equals 6, S(dim) can be 1,2,3, or 6).[R,I,J] = RANDBLOCK(...) also returns indices I and J, so that R equals A(I)and R(J) equals A. M can be a numerical or cell array. Examples: % Shuffle blocks of 3 elements of a 15-element vector M = 1:15 ; randblock(M,3) % Scramble a 2D matrix M = reshape(1:24,4,[]) ; randblock(A,[3 2]) % randomize the position of the four 3-by-2 blocks randblock(A,2) % randomize the position of the six 2-by-2 blocks % Scramble a 3D volume M = reshape(1:64,[4 8 2]) ; randblock(A,[2 4 2]) % randomize the position of the four % 2-by-4-by-2 sub-volumes % Scramble a cell matrix M = {'1','a','bb','1c' ; '2a',[3 4 5],'2c','2dd'} ; randblock(M,[2 2]) % randomize the position of the four 2-by-2 blocks % Scramble a RGB image Z, and retrieve the original using the % indices (see the SCREENSHOT) Z = peaks(200) ; Z = cat(3,Z,flipud(Z), -(circshift(Z.',[100,100]))) ; Z = (Z - min(Z(:))) ; Z = Z./ max(Z(:)) ; [Z2,I,J] = randblock(Z,[25,25,size(Z,3)]) ; % Scramble 25-by-25 blocks subplot(2,2,1) ; image(Z) ; title('Original image') ; subplot(2,2,2) ; image(Z2) ; title('25x25 scrambled image') ; subplot(2,2,3) ; image(Z2(J)) ; title('Z2(J) = original image') ; subplot(2,2,4) ; image(Z(I)) ; title('Z(I) = scrambled image') ; set (gcf,'Name','[Z2,I,J] = randblock(Z,[25,25,size(Z,3)])') ;

Requirements:	No special requirements
Platforms:	Matlab
Keyword:	0392a0393,  50392c0390392dd039,  Cat Zflipudz,  Image,  Original,  Peaks,  Randblockm,  Retrieve,  Screenshot
Users rating:	0/10