Transforming dates in numerical variables

[Ishto Stanfield]

Hello,

I have a date string variable in the following format "Jan-01" (month-year). I would like this variable to be numerical. Can anyone help?

Thank you

[Andrew Musau]

* Example generated by -dataex-. To install: ssc install dataex
clear
input str10 date
"Jan-01"
"Feb-99"
end
 
gen wanted= mofd(daily(date+"-01", "MYD", 2023))
format wanted %tm

Res.:

. l

     +-----------------+
     |   date   wanted |
     |-----------------|
  1. | Jan-01   2001m1 |
  2. | Feb-99   1999m2 |
     +-----------------+

[Nick Cox]

Almost all of what you need to know about dates (and times) is documented within

help datetime

Here the function monthly() does what you want. For individual dates, consider

. di monthly("Jan-01", "MY", 2025)
492

. di %tm monthly("Jan-01", "MY", 2025)
 2001m1

where 2025 is an upper limit on the year. If you need a different upper limit, you know what to do. If your data include e.g. monthly dates for July 1923 and July 2023, you're stuck.

You didn't give a data example in the sense of dataex (FAQ Advice #12). But a guess at what you want is

gen wanted = monthly(bad_date, "MY", 2025)

which you need to tweak according to actual and desired variable names.

[Ishto Stanfield]

Thank you, Andrew and Nick. Your support is really helpful.