speed up process of importing data from one vector to another

Hi. I have a vector with a timestamp (using Matlab numbers) which I want to import to another vector with a resolution of one second. The second vector is extremely large (since it contains a space for every second of the year 2011).

Here is my code so far: timestNUM: the original timestamp (containing Matlab datenums) VLeist: the original measurements

StartNUM = datenum(['01/01/2011',' 00:00:00'],'dd/mm/yyyy HH:MM:SS');
EndNUM = datenum(['31/12/2011',' 23:59:59'],'dd/mm/yyyy HH:MM:SS');
Step = 1./86400; %One second
timestSecNUM = (StartNUM:Step:EndNUM)';
VLeist_m = 10000.*ones(length(timestSecNUM),1); %the new vector which is to be filled

%the filling of the vector:
Progress = waitbar(0,'Filling high resolution vector with original values...');
x = length(VLeist); ct = 0;
for i = 1:x
    k = find(timestSecNUM == timestNUM(i));
    VLeist_m(k) = VLeist(i);
    ct = ct + 1;
    waitbar(ct./x);
end

The problem with my method is that the vectors tiemstNUM and VLeist have a length of over 500000. Because the resolution is supposed to be one second, the vectors VLeist_m and timestSecNUM each have a length of over 31.5 million!

You can imagine how long my loop takes... Any suggestions on how to speed up the process?

Thanks in advance!

[Marc Jakobi]

P.S. I know the waitbar slows it down even more. I use it while programming to get an idea of the speed...

Answer 1

[Walter Roberson]

Have you tried ismember() in its two-output version?

[tf, idx] = ismember(timestNUM, timestSecNUM);
VLeist_m(idx(tf)) = VLeist(tf);

No loop.

[Marc Jakobi]

Thanks so much! This seems to do the job in milliseconds!