Find the rows of a matrix A within another matrix B

Hi. I need to find the rows of matrix A (106x2) inside matrix B (172x2).

Matrix A should contain the values of all rows within B. Therefore, initially, I would like to know if there is a way to understand if all matrix A is contained in matrix B.

My goal, however, is to create a new matrix B ('B_new') characterized by '0's in the case where a row of A coincides with a row of B.

I explain this better with this image:

There is probably a more effective method than what I have written, like using the 'find' command.

At the moment I am using this code:

A = importdata("matrix_int.mat");
B = importdata("matrix_ext.mat");


B_new = {};

for K = 1:length(A)

    row_A = A(K,:);

    for K1 = 1:length(B)

        row_B = B(K1,:);

        if  row_A == row_B

            row_B = [0,0];

        end

        B_new = [B_new;{row_B}];

    end

end

Answer 1

[Bruno Luong]

Use ismember command with 'row' option

% Generate some dymmy date for testing
B=randi(4,10,2)

B = 10×2

1 4 4 4 3 2 4 2 4 3 3 2 1 4 2 1 2 2 2 4

A=randi(4,10,2)

A = 10×2

1 4 2 3 4 2 2 3 1 1 1 1 2 2 1 2 1 4 4 3

% Engine
B_new = B;
B_new(ismember(B,A,'row'),:) = 0;

% Check the result
B_new

B_new = 10×2

0 0 4 4 3 2 0 0 0 0 3 2 0 0 2 1 0 0 2 4

Answer 2

[Katy Weihrich]

%% example data generation
A = rand(10,2);
B = [rand(2,2); A(1:2,:); rand(2,2); A(5:7,:);  rand(2,2);  A(3:4,:); rand(2,2); A(1:2,:)];
% note: 
%% prep dataoutput
B_new = B;
%% seach for overlaps between A & B rows
% intersect will not obly give you the similarities between the arrays, but
% also the first (!) instance of them overlapping
[~,ia,ib] = intersect(A,B,'rows');
%% set oerlap to 0 in the dataoutput 
B_new(ib,:) = 0;
% note: since intersept only gives you the first occurence, if a row in A
% repeatetly occures in B there will some missed rows
%% repeat untill all overlaps are identified
B_prev = B;
while ~all(all(B_prev == B_new))
    B_prev = B_new; % 
    [~,ia,ib] = intersect(A,B_new,'rows');
    B_new(ib,:) = 0;
end