How to select the N elements then ignore the next N ones and then select the next N ones and so on?
foe example of the array a = 1:100;
b = 1,2,3,7,8,9,13,14,15,...
Approach # 1
a1 = reshape([a zeros(1,2*N - rem(numel(a),2*N))],N,[]);
out = reshape(a1(:,1:2:end),1,[]);
if rem(numel(a),2*N)<N
out = out(1:N*floor(numel(a)/(2*N)) + rem(numel(a),2*N)); %//output
end
Approach # 2
a1 = vec2mat(a,N)'; %//'
out = reshape(a1(:,1:2:end,:),1,[]);
if rem(numel(a),2*N)<N
out = out(1:N*floor(numel(a)/(2*N)) + rem(numel(a),2*N)); %//output
end
Approach # 3
mat1 = [true false];
mat2 = reshape(mat1(ones(N,1),:),[],1);
mat3 = reshape(mat2(:,ones(1,ceil(numel(a)/(2*N)))),[],1);
out = a(mat3(1:numel(a))); %//output