Converting dates into numbers

I have a int32 matrix of dates in the format YYYYMMDD and a cell array for time in the day in the format HH:MM. How can I combine both and turn it into a number I can use for plotting?

Answer 1

[Azzi Abdelmalek]

x=int32([19921212,19921213,19921214])'
y={'12:12', '13:13','14:14'}'
a=[num2str(x) char(y)]
b=datenum(a,'yyyymmddHH:MM')
datestr(b)

[Sergio]

perfect! Thanks Azzi

[Silver]

@Azzi and when I have the date format already sticked together like this: 2016.03.01 14:38:00 in a cell array how can I convert them to numeric so I can ue them in plot ? thks in advance

[Stephen23]

@Silver: read the datenum documentation.

Answer 2

[Peter Perkins]

Unless you're using a fairly old version of MATLAB, consider using datetimes instead of datenums. You will be happier.

>> x = int32([19921212,19921213,19921214])';
>> y = {'12:12', '13:13','14:14'}';
>> d = datetime(x,'ConvertFrom','yyyymmdd')
d = 
  3×1 datetime array
   12-Dec-1992 00:00:00
   13-Dec-1992 00:00:00
   14-Dec-1992 00:00:00
>> t = duration(y,'InputFormat','hh:mm')
t = 
  3×1 duration array
   12:12:00
   13:13:00
   14:14:00
>> dt = d + t
dt = 
  3×1 datetime array
   12-Dec-1992 12:12:00
   13-Dec-1992 13:13:00
   14-Dec-1992 14:14:00

Then just plot whatever vs. dt. You don't need to convert the datetimes to numeric.

Actually, creating the duration directly form text requires R2018a, prior to that do this:

>> t = timeofday(datetime(y,'InputFormat','HH:mm'))
t = 
  3×1 duration array
   12:12:00
   13:13:00
   14:14:00

or use text2duration on the File Exchange.