HOW CAN I RE-EDIT MATRIX?

Hi!

How can "re-edit" this matrix:

[1 3 4;

2 5 7;

3 1 6;

4 2 8]

in this:

[1 4;

1 4;

1 4;

2 7;

2 7;

2 7;

2 7;

2 7;

3 6;

4 8;

4 8]

where each row is replaced for n thimes where n is the second column in the first matrix?

Thank you!

Fabio

Answer 1

[José-Luis]

your_mat = cell2mat(arrayfun(@(n) repmat(a(n,[1 3]),a(n,2),1),(1:size(a,1))','uniformoutput',false));

[Fabio]

Thank you

Answer 2

[Geoff Hayes]

First determine the dimensions of the new matrix (called B say) which will mx2 where m is the sum of the middle column. Then iterate over each row of your initial matrix (called A say) and replicate the end points of that row (first and third columns) by the value in the second column:

B(j:j+A(i,2)-1,:) = repmat([A(i,1) A(i,3)],A(i,2),1);

where i is the ith row of A and j is the next row to insert your replicated block (with j being incremented on each iteration). So in the above piece of code, we are replacing all rows in B from j to j+A(i,2)-1 with the ends of the ith row of A replicated A(i,2)x1 times.

Hope that the above helps!

[Fabio]

Thank you