Stata: how to change a string variable to a date?
I'm new to Stata, and I'm wondering how can I change a string variable which contains a date to a date format.
The data in the variable looks like this:
yyyy-mm-dd
Should I first remove the dashes so that Stata can recognize the format in order to later use gen var = date() ?
Thank you for your help.
Answer
The Stata date function is smart about removing separator characters. See help datetime_translation under the section "the date function"
If your dates are in v1 and in the form yyyy-mm-dd you can specify the commands:
generate v2 = date(v1, "YMD")
format %td v2
The YMD is called a mask, and it tells Stata the order in which the parts of the date are specified. The second line will assign the variable the Stata daily date format, which means that when you look at that variable in the data, it will be shown in human readable form. The date is stored, however, as the number of days since January 1, 1960.
The best way to experiment with the date function is to use the display command. The first line will display an integer representing the number of days since January 1, 1960. The second line will display the date in a human readable format.
display date("2013-08-14", "YMD")
display %td date("2013-08-14", "YMD")