convert hourly data to daily sum

I have a mat file. Date and time (hour) in first column and melt in second column and I want to sum the hourly data into a daily value.

Answer 1

[David Hill]

load('hourmelt.mat');
a=[month(hourmelt.DateandTime),day(hourmelt.DateandTime),year(hourmelt.DateandTime)];
b=unique(a,'rows','stable');
c=arrayfun(@(x)sum(hourmelt.HourlyValue(ismember(a,b(x,:),'rows'))),1:length(b))';
newMatrix=[b,c];

Answer 2

[Peter Perkins]

Turn your table into a timetable, and use retime:

>> hourmelt = table2timetable(hourmelt);
>> head(hourmelt)
ans =
  8×1 timetable
        DateandTime        HourlyValue
    ___________________    ___________
    01/01/2015 00:00:00         0     
    01/01/2015 01:00:00         0     
    01/01/2015 02:00:00         0     
    01/01/2015 03:00:00         0     
    01/01/2015 04:00:00         0     
    01/01/2015 05:00:00         0     
    01/01/2015 06:00:00         0     
    01/01/2015 07:00:00         0     
>> head(dailymelt)
ans =
  8×1 timetable
        DateandTime        HourlyValue
    ___________________    ___________
    01/01/2015 00:00:00         0     
    02/01/2015 00:00:00         0     
    03/01/2015 00:00:00         0     
    04/01/2015 00:00:00         0     
    05/01/2015 00:00:00         0     
    06/01/2015 00:00:00         0     
    07/01/2015 00:00:00         0     
    08/01/2015 00:00:00         0     
>> head(dailymelt(dailymelt.HourlyValue > 0,:))
ans =
  8×1 timetable
        DateandTime        HourlyValue
    ___________________    ___________
    07/06/2015 00:00:00       0.03    
    08/06/2015 00:00:00       0.23    
    09/06/2015 00:00:00       0.32    
    10/06/2015 00:00:00       0.43    
    11/06/2015 00:00:00       0.47    
    12/06/2015 00:00:00       0.62    
    13/06/2015 00:00:00        0.6    
    14/06/2015 00:00:00       0.83