Subset data within time range

Hello,

I have a database of Date, Time and Value. I would like to create a subset of the variable 'Value' every 5 minutes, and extract the max, min and sum of this subset. Any ideias?

tks

Answer 1

[Mathieu NOE]

hello

my 2 cents suggestion

 [num,txt,raw] = xlsread('time_data.xlsx') ;
 
 timeday = num(:,1);       % time expressed in fraction of a day 24 hours
 data = num(:,2); 
 time_s = timeday*24*3600;
 
 samples = length(time_s);
 dt = (time_s(end)-time_s(1))/(samples-1);
%  t = (0:dt:(samples-1)*dt); % new time vector (unique values)
 Fs = 1/dt;
 
 % main loop : extract min max vales for every 5 min data %
 buffer_in_minutes = 5;     % put minutes here
 buffer_size = floor(buffer_in_minutes*60/dt);
 
 
 for ci = 1:floor(samples/buffer_size)
     ind_start = 1+(ci-1)*buffer_size;
     ind_stop = ind_start + buffer_size;
     data_tmp = data(ind_start:ind_stop);
     min_val(ci) = min(data_tmp);
     max_val(ci) = max(data_tmp);     
     sum_val(ci) = sum(data_tmp);
     time_index_s(ci) = mean(time_s(ind_start:ind_stop));
 end
 
 
 % x are you seconds values
s = seconds(time_index_s);  
% Change the duration format to hh:mm
s.Format = 'hh:mm:ss'; 


figure(1);
plot(s,min_val,'+',s,max_val,'+',s,sum_val,'+');grid

Answer 2

[Peter Perkins]

Your database appears to be a spreadsheet.

Don't use xlsread. Use readtimetable or readtable, depending on what version you have. Yopu will need to read in DATE and TIME as datetimes and durations (or convert them to those types) and add them together. Difficult to say exactly what this entails without knowing what version you have and precisely what is in your spreadsheet. Once you have a timetable, it's a one-liner to get what you want: retime. Three lines, actually, because you need three values.

tt = <some combination of readtable/readtimetable and conversion/addition to end up with a timetable with a var named VALUE>
tt1 = retime(tt,'regular','min','TimeStep',minutes(5));
tt2 = retime(tt,'regular','max','TimeStep',minutes(5));
tt3 = retime(tt,'regular','sum','TimeStep',minutes(5));
tt123 = [tt1 tt2 tt3];