Average of specific values based on condition

Hello, is it somehow to solve efficiently the following problem? I need to average only elements which are "together". See attached picture.

Answer 1

[KSSV]

data = [1 2 3 4 5 6 6.5 10 12 12.5 15 16 17 ;20 20 20 20 20 20 20 13 13 13 20 20 20]';

idx = find(diff(data(:,2))~=0) ;
pos = [[1 ;idx+1] [idx ; length(data)]] ;

iwant = zeros(size(pos,1),1) ;
for i = 1:size(pos,1)
    iwant(i) = mean(data(pos(i,1):pos(i,2),1)) ;
end

There would be more elegant procedures.