Accessing two matrices simultaneously in MATLAB

Question

I have two matrices, one of them is an adjacency matrix :

another matrix is storing indices of above matrix like this :

I want to apply some operations on say the 1st row of the matrix (i.e. [1 5 7]) simultaneously, how to access only 1st, 5th, and 7th row of original adjacency matrix in MATLAB?

Answer 1

You can use an array as the row index into the adjacency matrix and you can either store that in a temporary variable or pass that directly to a function.

tmp = adjacency([1 5 7], :);
dothing(tmp)

% Or
dothing(adjacency([1 5 7], :));

Also you can assign back into those same rows using the array as an index again

adjacency([1 5 7], :) = dothing(adjacency([1 5 7], :));