How to combine arrays

I have 3 2D arrays, let's call them A, B, C of equal dimensions.

What I want to do is return a combined array 'D' which has the same dimension as A, B, C. Where the value in A, B, C is 0, it will remain as 0. However, if a 1 appears in place in A,B,C it will then return a 1 at that particular location.

A =

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 1 0

0 0 0 0 0 0 0 1 1 1

0 0 0 0 0 0 1 1 1 1

0 0 0 0 0 0 0 1 1 1

0 0 0 0 0 0 0 0 1 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

B =

0 1 1 1 0 0 0 0 0 0

1 1 1 1 1 0 0 0 0 0

0 1 1 1 0 0 0 0 0 0

0 0 1 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

C =

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0

1 1 1 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0

Answer 1

[Sriram Tadavarty]

Hi,

The following should help you do it:

D = zeros(size(A));
D(A==1 | B == 1 | C == 1) = 1;

Hope this helps.

Regards,

Sriram

[Jonathan]

Thanks this helps tremendously. Is there anywhere to write this in a loop since I don't know how many arrays of A,B,C I will eventually have?

[Sriram Tadavarty]

I am pretty not sure how you are storing those many arrays? If it is with separate variables, it is highly unlikely you can use a loop.

[Jonathan]

I don't know how I will store the arrays yet. I was thinking maybe in a container array. So esentially an array of arrays?

Maybe I should store these data in separate variables then and then add it to a container array?

[Sriram Tadavarty]

Do accept the answer, if it helps for the question asked.

Ok, if that is the case, you can try the following:

% Assuming S is an array of arrays (implies M x N x P)
% M - number of rows
% N - number of columns
% P - number of such matrices
D = zeros(M,N);
index1Loc = sum(S,3) ~= 0;
D(index1Loc) = 1;

% If you already have the variables, take a matrix
D = zeros(M,N);
D(A) = D(A)+1;
D(B) = D(B)+1;
D(C) = D(C)+1; % You need add up manually all the variables
D = (D >= 0);

Hope these helps.

Regards,

Sriram

[Stephen23]

"I don't know how I will store the arrays yet."

If the sizes are the same then one ND array would be best. It would trivial to access using indexing.

https://www.mathworks.com/help/matlab/math/multidimensional-arrays.html

"I was thinking maybe in a container array."

A container array would also work, but likely would be slightly less efficient.

https://www.mathworks.com/help/matlab/cell-arrays.html

"Maybe I should store these data in separate variables then and then add it to a container array?"

That would be about the worst way to approach this. Accessing variable names dynamically is one way that beginners force themselves into writing slow, complex, obfuscated, buggy code that is hard to debug. Read more:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval