Handling time in Matlab

Question

I have a data set with 2 columns. The Column 1 is hours from midnight 2013 and Column 2 is quantity. The Column 1 considers the absolute hours from midnight and hence doesn't account for day light savings. How do I generate a Column 3 which is date and Column 4 which is hour from my data.

An idea I had was to correspond the hours to GMT and then change it back to US eastern time. But again I am having trouble implementing it.

This is what I have as a data:

Hours from 
midnight 2013     Quantity
28                  45
29                  74
30                  65
31                  14
36                  13
48                  4

This is what I desire:

Hours from 
midnight 2013     Quantity                  Date                      Hour
28                  45                  1/2/2014               4     
29                  74                  1/2/2014               5
30                  65                  1/2/2014               6
31                  14                  1/2/2014               7
36                  13                  1/2/2014               12
48                  4                   1/2/2014               24

Answer 1

OK, here's how I would do it in Octave. The syntax may be slightly different in MATLAB, but the idea is the same:

>> hh = [28 29 30 31 36 48];
>> midnight = datenum(2014,1,1,0,0,0);
>> dates = datestr(midnight+hh/24,'mm/dd/yyyy')
dates =

01/02/2014
01/02/2014
01/02/2014
01/02/2014
01/02/2014
01/03/2014
>> hhs = (midnight+hh/24-datenum(2014,1,2,0,0,0))*24
hhs =

           4           5           6           7           12          24

I haven't accounted for day light savings.

Answer 2

I'll do it this way in matlab 2013a:

minuit = [2014 01 01 00 00 00]
col3 = addtodate(datenum(minuit),28,'hour')

then

datestr(col3,'HH') % for your Hour column
datestr(col3,'mm/DD/YYYY') % for your Date colum