I want to extract specific data from a matrix and organize in another matrix

Hi-

I have a 3x3 matrix A=[1 2 3; 5 7 9; 4 6 8] and want to use the digits to extract data from the row and column they represent in another 9x9 matrix B=[0 2 4 3 2 4 5 2 7; 2 0 4 3 2 4 5 2 7; 3 4 0 9 8 7 4 3 2; 9 4 3 0 2 3 9 8 7; 3 2 1 9 0 9 3 2 4; 9 4 5 6 3 0 9 3 2; 3 2 4 5 6 7 0 3 9; 4 3 2 5 7 6 4 0 9; 4 3 4 5 4 3 2 5 0] and place the answer in matrix C. C should be equal to [B(1,2) B(1,3) B(2,3); B(5,7) B(5,9) B(7,9); B(4,6) B(4,8) B(6,8)]. I hope this makes sence. It should walk the A matrix finding every interaction for the row and col coordinates to extract from B. Thanks!

Answer 1

[Image Analyst]

Try this:

A=[1 2 3; 5 7 9; 4 6 8]

A = 3×3

1 2 3 5 7 9 4 6 8

% and want to use the digits to extract data from the row and column they represent 
% in another 9x9 matrix 
B=[0 2 4 3 2 4 5 2 7; 2 0 4 3 2 4 5 2 7; 3 4 0 9 8 7 4 3 2; 9 4 3 0 2 3 9 8 7; 3 2 1 9 0 9 3 2 4; 9 4 5 6 3 0 9 3 2; 3 2 4 5 6 7 0 3 9; 4 3 2 5 7 6 4 0 9; 4 3 4 5 4 3 2 5 0]

B = 9×9

0 2 4 3 2 4 5 2 7 2 0 4 3 2 4 5 2 7 3 4 0 9 8 7 4 3 2 9 4 3 0 2 3 9 8 7 3 2 1 9 0 9 3 2 4 9 4 5 6 3 0 9 3 2 3 2 4 5 6 7 0 3 9 4 3 2 5 7 6 4 0 9 4 3 4 5 4 3 2 5 0

% and place the answer in matrix C. 
% C should be equal to [B(1,2) B(1,3) B(2,3); 
%                       B(5,7) B(5,9) B(7,9); 
%                       B(4,6) B(4,8) B(6,8)]. 
C = [...
    B(A(1,1), A(1, 2)), B(A(1,1), A(1,3)), B(A(1,2), A(1,3));...
    B(A(2,1), A(2, 2)), B(A(2,1), A(2,3)), B(A(2,2), A(2,3));...
    B(A(3,1), A(3, 2)), B(A(3,1), A(3,3)), B(A(3,2), A(3,3))
    ]

C = 3×3

2 4 4 3 4 9 3 8 3

[Daniel]

Thank you!