Try this:
% First we need to create the data since the original poster forgot to attach it for us.
% Make random vector with values in the 1-9 range.
v = randi(9, 1, 24000);
% Make 20 stretches of 72 zeros.
startingIndexes = sort(randi(length(v), 1, 20))
for k = 1 : length(startingIndexes)
v(startingIndexes(k) : startingIndexes(k) + 71) = 0;
end
% Now we have our vector and we can begin.
%---------------------------------------------------------------------------------
% First find out what the non-zero values are
% that we can use to plug the regions of zeros.
% tic; % Start timer
availableToUse = unique(nonzeros(v));
% Now plug the zeros with numbers randomly chosen from availableToUse
for k = 1 : length(v)
if v(k) == 0
% It's zero so replace it with a random number chosen from availableToUse.
randomIndex = randi(length(availableToUse), 1, 1);
v(k) = availableToUse(randomIndex);
end
end
% toc % End timer
Time to execute is 0.002 seconds (2 milliseconds).
