Generating index from end and start index

I am looking for an efficient way to do the following (without a loop so that large array can be handled efficiently). Any idea ?

      A=rand(1,30) % some data from which I want to extract a subset    
      s=[1 5 10 22]; % start indexes of the subsets I want to extract
      e=[3 7 17 25]; % end indexes of the subset I want to extract

      R=[];
      for i=1:length(s)
          R=[R [s(i):e(i)]];
      end
      S=A(R); % the answer I am looking for, i.e. the subset of data I want to 
              % extract

[per isakson]

1. Did you analyze your code with the function, profile?
2. Which version of Matlab do you use?

Answer 1

[Matt Fig]

If you don't want to use a mex file, this is very fast:

% Make your index into A
L = length(s);
F = cumsum(e-s+1);
idx = ones(1,F(end));
idx(1) = s(1);
idx(1+F(1:L-1)) = s(2:L)-e(1:L-1);
idx = cumsum(idx);

% Now use it as you need:
S = A(idx);

Answer 2

[Oleg Komarov]

I recommend the nice submission by Bruno Luong: multiple colon.

Use the mex routine, very fast and reliable.

Answer 3

[Azzi Abdelmalek]

    A=rand(1,30)  ;   
    s=[1 5 10 22];
    e=[3 7 17 25]; 
  l=repmat(1:4,2,1);
  idx=eval(['[' sprintf('s(%d):e(%d) ',l(:)') ']'])
  S=A(idx)