How to retrieve location values in a matrix

3 views (last 30 days)
Danish Nasir on 24 Jul 2021
Commented: Danish Nasir on 24 Jul 2021
Suppose i have a matrix 4x6 i.e. 6 columns and 4 rows. I want to extract different location values from the matrix i.e. 3rd location from column 1, 4th location value from column 2, 1st location value from column 3 etc. ([ 3 4 1 5 2 2]). Then i have to add these column location values. Pls suggest the code.

Chunru on 24 Jul 2021
% Generate a 4X6 matrix
a = randi(10, 4, 6)
a = 4×6
7 6 6 8 8 6 5 6 4 7 5 8 2 8 6 7 1 1 2 6 9 3 6 6
% The index to each column
%idx = [ 3 4 1 5 2 2] % 5 is not correct
idx = [ 3 4 1 4 2 2];
% Fund the corresponding linear index
ii = sub2ind([4, 6], idx, 1:6);
% Show the extracted data
a(ii)
ans = 1×6
2 6 6 3 5 8
sum(a(ii))
ans = 30
Danish Nasir on 24 Jul 2021
Actually i want to take indices of matrix a (4x6), and want to extract the values of some other matrix b (4x6) of same size with these indices.

Sulaymon Eshkabilov on 24 Jul 2021
% e.g.:
A = randi([0, 13], 4,6)
A = 4×6
8 12 8 6 10 4 9 2 1 3 7 1 2 6 5 5 0 1 3 3 10 10 9 1
A(3,1), A(4, 2), A(1,3)
ans = 2
ans = 3
ans = 8