Clustering GPS times based on the hour of the day

Hello,

I have some raw GPS data that is sampled every 10 minutes or so. I also have the initial timestamp that is the initial recording date and time. I am trying to write a function that returns the index of observations that falls into particular hours of the day, ie. in the hour intervals [ a, b] and [ c, d] (24h clock) and also outside these hours. I try to divide observations contained into these two intervals vs. those outside of these intervals. Thus, all values that fall inside the one of the two intervals are in a vector ' d1' and values outside are in vector ' d2'.

More precisely, my data looks like this:

timeStamp = '16/01/2010__00:01:00' %t0
t %a 1*n vector of time intervals: t = [...,9,10,11,10,10,9,8,10,...]
h %vector of time intervals to split the serie: h = [a,b,c,d]

I would like my function to return the indexes of values that fall to one of the two sets ( d1 or d2). The vector t can be large (more than 30000 observations) and I would ideally like something

For instance: if h = [1,4,18,22] and current t(i) translates to 7h21m56s (inside), it will be set in partition ' d2', if t(i) translates to 22h12m57s (thus outside the interval) in partition ' d1' and so on.

I made an utterly complicated function long time ago that doesn't seem to work. I am thus looking for something simpler and accurate.

My pseudo solution was:

function [d1, d2] = Create_TimeClasses(t, timeStamp, h)
%Create time classes (millisecond precision):

t0 = datenum(timeStamp);
%Reconstruct date vector:
k=1; l=1;
formatOut = 'HH:MM:SS.FFF';

ted = t0;
for i=2:size(t,2)
    MM = floor(t(i));
    ss = t(i)-MM;
    SS = floor(ss*100); %2-digits seconds;
    FFF = round((ss*100-floor(ss*100))*1000); %3-digits milliseconds precision.
    %recreate the string: format: HH:MM:SS.FFF (FFF milliseconds) to take
    %into account the side effects:
    S = strcat('0:',num2str(MM), ':', num2str(SS), '.', num2str(FFF));
    Str = datestr(S,formatOut); %String should now be ok
    %Then gather the time and extract the number of milliseconds:
    [~,~,~,hours,minutes,seconds] = datevec(Str, formatOut);
    mSt = round(1000*(3600*hours + 60*minutes + seconds)); %milliseconds

      %add to date
      ted = addtodate(ted, mSt, 'millisecond');
      aaa = datestr(ted, formatOut);
      hed = str2double(aaa(1:2)); %hours
      med = str2double(aaa(4:5)); %minutes
      sed = str2double(aaa(7:8)); %seconds
      %Correct for additional seconds:
      if(sed/0.6 >= 1)
          med = med+1;
      end
      hed = hed + mod(med/60, 24) + sed;

      %Interesting activity time zone?
      if(hed >= h(1) && hed <= h(2) || hed >= h(3) && hed <= h(4))
          d1(k) = i; %yes
          k=k+1;
      else %non-activity time zone:
          d2(l) = i;
          l=l+1;
      end
  end

Thank you