create a sparse multidimensional matrix

Hi all,

I am trying to construct a multidimensional sparse matrix that has the following shape:

I have a problem knowing how to jump from column to the next, shift the rows downwards, and assign number 1 to the third element.

Any help would be appreicted.

Thanks.

Answer 1

[Jonas]

you can try this:

myData=[1  2  3  4; 
        5  6  7  8; 
        9 10 11 12];

% get sizes
dataChunkLength=size(myData,2);
numOfChunks=size(myData,1);

% preallocate
mat=zeros(dataChunkLength*numOfChunks,numOfChunks);
for colNr=numOfChunks:-1:1
    % write
    mat(1:dataChunkLength,colNr)=myData(colNr,:);
    if colNr>1
        % and shift along first dimension
        mat=circshift(mat,dataChunkLength,1);
    end

end
disp(mat)

     1     0     0
     2     0     0
     3     0     0
     4     0     0
     0     5     0
     0     6     0
     0     7     0
     0     8     0
     0     0     9
     0     0    10
     0     0    11
     0     0    12

or, if you waqnt to write alswys the same data

myData=[0 0 1 0];

% get length
dataChunkLength=numel(myData);

% write to n columns
nTimes=5;

% preallocate
mat=zeros(dataChunkLength*nTimes,nTimes);

for colNr=nTimes:-1:1
    % write
    mat(1:dataChunkLength,colNr)=myData;
    
    if colNr>1
        % and shift along first dimension
        mat=circshift(mat,dataChunkLength,1);
    end


end
disp(mat)

     0     0     0     0     0
     0     0     0     0     0
     1     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     1     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     1     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     1     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     1
     0     0     0     0     0

Answer 2

[Torsten]

i(1) = 3;
j(1) = 1;
v(1) = 1.0;
i(2) = 7;
j(2) = 2;
v(2) = 1.0;
i(3) = 11;
j(3) = 3;
v(3) = 1.0;
m = 12;
n = 3;
A = sparse(i,j,v,m,n)

A = 
   (3,1)        1
   (7,2)        1
  (11,3)        1

Answer 3

[Karim]

you can either fill it in directly or use blkdiag to create this shape:

% direct method
% on row 3 7 and 11, column 1 2 3 respectivly, fill in 1, with 12 rows and 3 columns
SparseDirect = sparse([3 7 11],[1 2 3],1,12,3)

SparseDirect = 
   (3,1)        1
   (7,2)        1
  (11,3)        1

% alternative using blkdiag
A = sparse( [0;0;1;0] );
B = sparse( [0;0;1;0] );
C = sparse( [0;0;1;0] );


SparseMat = blkdiag(A,B,C)

SparseMat = 
   (3,1)        1
   (7,2)        1
  (11,3)        1

% full visualisation
full(SparseMat)

ans = 12×3

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Answer 4

[Matt J]

n=3;

A=kron(speye(n),[0;0;1;0])

A = 
   (3,1)        1
   (7,2)        1
  (11,3)        1

full(A)

ans = 12×3

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0

Answer 5

[KSSV]

A = sparse(12,3) ;
A(3,1) = 1 ;
A(7,2) = 1 ;
A(11,3) = 1 ; 
A

A = 
   (3,1)        1
   (7,2)        1
  (11,3)        1

full(A)

ans = 12×3

0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0