How to remove rows?

mydata = importdata('data.txt'); A=mydata;

    nRows = size(A, 1);
    nColumns = size(A,2);

        for i=1: nRows
            if (nnz(A(i,:)<3540) == 15)
                A(i,:)=[];
            end
        end

Answer 1

[José-Luis]

You don't need to loop

 A(sum(A < 3540, 2) == 15,:) = [];

[Justyna Slawska]

thx :)

Answer 2

[Steven Lord]

If you must loop (a requirement of a homework assignment, for instance) inside the loop you should not actually delete the rows of the matrix. Instead record which rows need to be deleted and delete all of them after the loop is complete. Why?

x = 1:10;
n = numel(x);
for k = 1:n
  fprintf('x contains %d elements, processing element %d of %d.\n', ...
    numel(x), k, n);
  if mod(x(k), 2) == 0
    x(k) = [];
  end
end

In this code you're shortening x every other iteration, and eventually you "walk off the end" of the array. Unlike Bugs Bunny, MATLAB notices immediately. Instead of chopping pieces off the array immediately, identify which pieces need to be removed then remove then once identification is complete.

x = 1:10;
n = numel(x);
toBeDeleted = false(size(x));
for k = 1:n
  fprintf('x contains %d elements, processing element %d of %d.\n', ...
    numel(x), k, n);
  if mod(x(k), 2) == 0
    toBeDeleted(k) = true;
  end
end
x(toBeDeleted) = []