Creating a new matrix basd on the index and value of an existing matrix

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Rong Sun on 24 Sep 2021
Commented: Rong Sun on 27 Sep 2021
Hi all,
I am new to matlab and I need your help on this.
I have a m x n matrix and I want to create a new m*n x 3 matrix in which the third column is the value from first matrix and the first two columns are the corresponding index of the value. For example, if the first matrix is [0.001 0.002 0.003 0.004; 0.005 0.006 0.007 0.008], I would like to make a matrix as [1 1 0.001; 1 2 0.002; 1 3 0.003; 1 4 0.004; 2 1 0.005; 2 2 0.006; 2 3 0.007; 2 4 0.008].
So how can I create the second matrix based on the index and value of first matrix?

Kumar Pallav on 27 Sep 2021
You could try the following code in matlab to get the desired result:
input=[0.001 0.002 0.003 0.004; 0.005 0.006 0.007 0.008];
[nrows ncols]=size(input); %stores the number of rows and columns in input
values=[]; %output matrix
for r=1:nrows
for c=1:ncols
values=[values;r c input(r,c)];% keep appending [r,c,input] to new columns
end
end
disp(values); %display the output
Hope this helps!
Rong Sun on 27 Sep 2021
Thanks, Kumar!

R2020a

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