Cumulative sum for every 15min from 1 min timeseries data

I have a precitpitation data at every 1 min interval. I want to change the timeseries to make a cumulative sum at every 15 min, in order to create a 15-min precipitation data. Which command would be the most suitable for this? Any Help?

Answer 1

[Jos (10584)]

Do you want to sum up the 15 minutes to a single number and then proceed to the next 15 minutes?

V = ceil(5*rand(33,1)) ; % some 33 arbitrary values
T = 0:numel(V)-1 ; % time stamps
interval = 15 ;

ix = 1+floor((T-T(1))/interval) 
V2 = accumarray(ix(:),V(:))
isequal(V2(1),sum(V(1:interval))) % check

[Meh]

Great! Thanks Jos! I have one question though, why did you take T(1)? istn T(1) always zero?

[Jos (10584)]

Only if you define it as such! By subtracting T(1) from the time data you are sure that the indices correspond to the right indices (intervals), otherwise they might be shifted. The subtraction ensures that the first points within Interval from T(1) receive the index 1, etc ...