Combining two datetime columns into one

Hi

I am trying to combine two columns in a table that are formated as datetime. Date is in format 'mm/dd/yyy' and Time is in format 'HH:mm'

I have tried:

%Obs_data.Timestamp = Obs_data.Date + Obs_data.Time;

Error

Addition is not defined between datetime arrays.

Answer 1

[Star Strider]

Another option is to use timeofday —

Date = repmat(datetime('now','Format','MM/dd/yyyy'), 3, 1);
Time = datetime('now','Format','HH:mm','Timezone','UTC-7') + hours(0:2).';
Obs_data = table(Date,Time)

Obs_data = 3×2 table
       Date       Time 
    __________    _____

    03/09/2022    08:54
    03/09/2022    09:54
    03/09/2022    10:54

Obs_data.Timestamp = Obs_data.Date + timeofday(Obs_data.Time)

Obs_data = 3×3 table
       Date       Time     Timestamp 
    __________    _____    __________

    03/09/2022    08:54    03/10/2022
    03/09/2022    09:54    03/10/2022
    03/09/2022    10:54    03/10/2022

Obs_data.Timestamp.Format = 'MM/dd/yyyy HH:mm'

Obs_data = 3×3 table
       Date       Time        Timestamp    
    __________    _____    ________________

    03/09/2022    08:54    03/10/2022 00:48
    03/09/2022    09:54    03/10/2022 01:48
    03/09/2022    10:54    03/10/2022 02:48

.

[Autumn P]

This worked, thank you!

[Star Strider]

As always, my pleasure!

Answer 2

[David Hill]

d=[Obs_data.Date,' ',Obs_data.Time];
datetime(d,'InputFormat','MM/dd/yyyy HH:mm');

[Autumn P]

This did not work for me. I got the following error

Error using datetime/horzcat (line 1387)

Dimensions of arrays being concatenated are not consistent.

[David Hill]

d=[Obs_data.Date,repmat(' ',size(Obs_data.Date,1),1),Obs_data.Time];%assuming the dates and times are character arrays
%d=[char(Obs_data.Date),repmat(' ',size(Obs_data.Date,1),1),char(Obs_data.Time)]; 
%use above to convert to char arrays if necessary
datetime(d,'InputFormat','MM/dd/yyyy HH:mm');

Answer 3

[Steven Lord]

Why is your Time data stored as a datetime array? IMO it would make more sense for you to import or create it as a duration array.

I don't know how to add yesterday and tomorrow in a way that makes sense but I know how to add right now and 6 hours.

rightNow = datetime('now')

rightNow = datetime
   09-Mar-2022 14:45:42

h = hours(6)

h = duration
   6 hr

sixHoursFromNow = rightNow + h % datetime + duration = datetime

sixHoursFromNow = datetime
   09-Mar-2022 20:45:42

If you're reading your time data as text (say from a file) you can convert that to a duration array pretty easily.

h2 = duration('01:23', 'InputFormat', 'hh:mm')

h2 = duration
   01:23:00

anHour23MinutesFromNow = rightNow + h2

anHour23MinutesFromNow = datetime
   09-Mar-2022 16:08:42