adding one day to a date

[Dusan Petrovic]

Dear Statalisters,

I have a date variable which is in the following format (it is not a string) :

browse date
. 30dec1899 23:09:25
...

I would like to add one extra day to this date, if the hours are between 00:00 (midnight) and 04:59 am

I proceed like this

capt drop hours
gen hours=hours(date)


replace date=date+1 if hours<5

However stata does not produce any changes (0 replacement made). I checked on the internet already, but I cannot find a solution.

Thank you for kind your help and your understanding

[Joe Canner]

Dusan,

Assuming your variable is a Stata datetime variable (format %tc...), the correct function to get the hour of the day is hh() not hours().

You are also going to have trouble just adding one to get the next day. A Stata datetime variable is the number of milliseconds since 1/1/1960 at midnight, so to add a full day you will have to add 24*60*60*1000 milliseconds (or something less than that if you don't want to add a full 24 hours).

Regards,
Joe

[Dusan Petrovic]

Thanks a lot Joe!

[Roberto Ferrer]

You are using an incorrect function and not considering you need milliseconds.

clear
set more off

*----- example data -----

input ///
str25 event
"30dec1899 23:09:25"
"30dec1899 01:15:12"
"30dec1899 04:59:59"
end

gen double event2 = clock(event, "DMYhms")
format %tc event2
list

*----- what you want -----
 
gen double event3 = event2 + msofhours(24) if hh(event2) < 5
format %tc event3
list event?

Read -help datetime- carefully, as well as the corresponding manual entries.