Find the common elements in same indices in two arrays.

Suppose,

A = [1001 1002 1003 2001 2002 1004 1005 2003 2004 2005]

B = [1001 1002 2001 2002 1003 1004 2003 1005 2004 2005]

X and Y are two arrays with zero elements

X = [0 0 0 0 0 0 0 0 0 0]

Y = [0 0 0 0 0 0 0 0 0 0]

(1) Now I want to find the common elements that are in the same indices of A and B and put in X and Y.

Answer will be:

X = [1001 1002 0 0 0 0 1004 0 2004 2005]

Y = [1001 1002 0 0 0 0 1004 0 2004 2005]

(2) Now generate two random indices; e.g., 5 and 7

Now, I want to replace the elements of X and Y between the random indices (5 and 7) with the elements of A and B, respectively.

Answer will be:

X = [1001 1002 0 0 2002 1004 1005 0 2004 2005]

Y = [1001 1002 0 0 1003 1004 2003 0 2004 2005]

(3) Now I want to replace the zero elements of X with the elements of B (that are not in X; i.e., 2001, 1003 and 2003), following the same relative order of the elements.

Also, I want to replace the zero elements of Y with the elements of A (that are not in Y; i.e., 2001, 2002 and 1005), following the same relative order of the elements.

Answer will be:

X = [1001 1002 2001 1003 2002 1004 1005 2003 2004 2005]

Y = [1001 1002 2001 2002 1003 1004 2003 1005 2004 2005]

How can I do these? Thanks in advance.

[Voss]

You can use randi to generate random indices, e.g.:

% generate two integers between 1 and numel(X) - the number of elements of
% X - and sort them so that rand_idx(2) >= rand_idx(1) so you can do 
% indexing like: X(rand_idx(1):rand_idx(2))
rand_idx = sort(randi(numel(X),1,2));

Answer 1

[Davide Masiello]

clear,clc

A = [1001    1002    1003    2001    2002    1004    1005    2003    2004    2005];
B = [1001    1002    2001    2002    1003    1004    2003    1005    2004    2005];

X = zeros(size(A));

X(A == B) = A(A == B);
Y = X;

rand_idx = [5,7];

X(rand_idx) = A(rand_idx);
Y(rand_idx) = B(rand_idx);

X(X == 0) = B(X == 0);
Y(Y == 0) = A(Y == 0);

fprintf(['X = [',repmat('%d ',size(X)),']'],X)

X = [1001 1002 2001 2002 2002 1004 1005 1005 2004 2005 ]

fprintf(['Y = [',repmat('%d ',size(Y)),']'],Y)

Y = [1001 1002 1003 2001 1003 1004 2003 2003 2004 2005 ]