# Datenum with a.m. and p.m.

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Brenton Hirao on 15 Nov 2019
Commented: Adam Danz on 15 Nov 2019
I have a data set with timestamps:
'11/5/2019 12 a.m. EST'
...
'11/10/2019 1 p.m. EST'
How can I convert these timestamps into a vector of date numbers?
thanks for the help.

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Walter Roberson on 15 Nov 2019
Are the periods part of the text? Is it possible for the time zone to be anything other than EST (for example can it be EDT? Can it be GMT? PDT?)
Brenton Hirao on 15 Nov 2019
Walter Robinson, the periods are part of the text. The data only contains EST.
Adam Danz on 15 Nov 2019
So you're converting from strings to datenum?
https://www.mathworks.com/help/matlab/ref/datenum.html
It might be necessary to remove the dots first using strrep but maybe not (my machine has been shut down for the night).

Shubham Gupta on 15 Nov 2019
Assuming there is ".m. EST" attached to each "timestamp" at the end. You can follow the steps:
Step-1 Replace ".m. EST" to just "m" (Hint : regexprep)
Step-2 Convert the output into the date numbers (Hint: datenum)
You should get the output with date numbers in a array. (Not sure what do mean by "continuous"?)

Walter Roberson on 15 Nov 2019
S = '11/5/2019 12 a.m. EST';
temp = regexprep(S, '\.m\.', 'm');
t = datetime(temp, 'Inputformat', 'd/M/yyyy h a z', 'TimeZone', 'America/Chicago');
The above will have "eastern time" as the attached timezone. You can switch it to EST but you will get a warning,
Warning: 'EST' specifies a time zone with a fixed offset from UTC, -05:00. This zone does not follow daylight saving time, and so may give unexpected results. See the datetime.TimeZone property for details about specifying time zones.
Adam Danz on 15 Nov 2019
Instead of the regexprep() you could also do
temp = strrep(S,'.','');