Clean solution to shrink matrices

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Pappu Murthy
Pappu Murthy 2017-5-9
回答： Prema Gopalakrishnan 2019-7-23
I have pre-allocated a large Matrix X = (80000,8). for e.g zeros(80000,8); This I did for speed. After several operations I only filled say 1000 rows of the matrix and remaining are all zeros as I pre-allocated all elements to be zero to start with. Now I would like the shrink the matrix to smaller one by eliminating all the trivial rows in the end. What is the cleanest way of doing them?

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Prema Gopalakrishnan
X = X(1:n,:);

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John D'Errico
John D'Errico 2017-5-9
As long as you know how many rows are filled (call it n, here n is 1000), then just do
X = X(1:n,:);

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