How to group IDs in Stata

[Adeola Akintola]

Hello.
I need to group the cases into two by the IDs using the last character (N or P).
How do I do this in stata.
A sample of the study IDs is listed below.
Thank you.

[CODE]
* Example generated by -dataex-. For more info, type help dataex
clear
Sty_id
"ADH001N"
"ADH001P"
"ADH002N"
"ADH002P"

[Øyvind Snilsberg]

gen wanted = regex(Sty_id,"N$")

[Andrew Musau]

You appear to have edited the dataex output. You should post the exact output as whether the variable Sty_id is a string variable or a numerical variable with value labels is crucial.

gen which= substr(Sty_id, -1, 1)
sort which
l, sepby(which)

[Rich Goldstein]

and here is a solution that does not use regular expressions:

gen byte wanted = inlist(substr(Sty_id,-1,1),"N","P")

note that since you butchered your -dataex- example (please don't do that), this is not tested

[Adeola Akintola]

The codes worked. Thank to everyone for your assistance. I have also noted the point raised by Andrew Musau and Rich Goldstein on edited output. I need your expert advise on how to improve my coding in stata. Thank you.