How to store data in a pre allocated array

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Alex
Alex 2022-12-14
评论： Jan 2022-12-14
I have a pre-allocated array. But I want to store in that array 2 values, but it gets overwritten and only stores the last value. How could I fix that?
Note: I'am comparing the values of the odd and even columns of a random matrix in a loop.
Matrix = randi([0, 1], [1000,1000]);
MatrixEven=Matrix(:,2:2:end);
MatrixOdd=Matrix(:,1:2:end);
[rows,columns]=size(MatrixEven);
[rows1,columns1]=size(Matrix);
Array_Result=NaN(rows1,columns1); %Same size as Matrix
for i=1:1:rows
for j=1:1:columns
if MatrixOdd(i,j)==MatrixEven(i,j)
Array_Result(i,j)=2; % If equal stores two '2'
Array_Result(i,j)=2;
else
Array_Result(i,j)=MatrixOdd(i,j); %If different, stores both values
Array_Result(i,j)=MatrixEven(i,j);
end
end
end

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采纳的回答

Jan
Jan 2022-12-14
Of course you overwrite the values, see:
Array_Result(i,j)=2;
Array_Result(i,j)=2;
You cannot store two values in one element.
I guess you mean:
for i = 1:rows
for j = 1:columns
j2 = (j - 1)*2 + 1;
if MatrixOdd(i,j) == MatrixEven(i,j)
Array_Result(i, j2) = 2; % If equal stores two '2'
Array_Result(i, j2+1) = 2;
else
Array_Result(i, j2) = MatrixOdd(i,j); %If different, stores both values
Array_Result(i, j2+1) = MatrixEven(i,j);
end
end
end
A simpler code for the same result:
Result = Matrix;
Mask = MatrixEven == MatrixOdd;
Result(repelem(Mask, 1, 2)) = 2;

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