MATLAB: How do i do this

compareloops

I have
R = input('Please enter a number of rows for the matrix')
C = input('Please enter a number of columns for the matrix')
M = randi(2, R, C)
for M2 = 1:numel(M)
    if M(M2) > 1
       M(M2) = -1
    end
end
M3 = M
for MN = 1:numel(M3)
I need to: Part c: You will need to use a loop to check the neighbors of each element and then count how many agree with the current element you are on. You will need to check the elements to the left, right, above and below. You will probably need to create another matrix to keep track of the similar spin count.
How do i do this?

Best Answer

Hi, I am assuming that you are trying to compare M3(i,j) with it's adjacent elements and you want to store the number of times M3(i,j) matches with adjacent elements in a new variable c(i,j). You can do this by creating a new matrix of size (R+2,C+2).
R = input('Please enter a number of rows for the matrix');
C = input('Please enter a number of columns for the matrix');
M = randi(2, R, C);
M(M>1)=-1; % instead of "for M2 = 1:numel(M) if M(M2) > 1 M(M2) = -1 end end"
M3 = M;
M4=NaN(R+2,C+2); 
M4(2:end-1,2:end-1)=M3;
c=zeros(R,C);
for i = 2:R+1
    for j=2:C+1
        arr = [M4(i-1,j) M4(i+1,j) M4(i,j+1) M4(i,j-1)];
        c(i-1,j-1)=nnz(ismember(arr,M4(i,j)));      
    end
end
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