HOW CAN I RE-EDIT MATRIX?

Question

Fabio 2014-5-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/130665-how-can-i-re-edit-matrix

评论： Fabio 2014-5-22

采纳的回答： José-Luis

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;

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

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Answer 1

José-Luis 2014-5-22

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

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Fabio 2014-5-22

Thank you

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Answer 2

Geoff Hayes 2014-5-22

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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!