Keeping variables from a list

[Fernando Bastidas]

Hello everyone,

I'd like to know if there's a way to keep in my dataset, the observations that are returned from a list. To give you some context, I have a panel data set, where I want to keep just some IDs that satisfy certain condition on the initial year. So I get the list of the IDs that I need, but it's too large to write a keep if, so I would like to keep the observations that only have those IDs.

Below it's the code that returns the IDs (which are called mrun in this database) that I need to keep.

list mrun if cod_ense2==2 & agno==2016 & (cod_grado==1 | cod_grado==2 | cod_grado==3 | cod_grado==4)

Thanks!

[Nick Cox]

 cod_ense2==2 & agno==2016 & (cod_grado==1 | cod_grado==2 | cod_grado==3 | cod_grado==4)

can be abbreviated to

cod_ense2==2 & agno==2016 & inlist(cod_grado, 1, 2, 3, 4)

and almost certainly to

cod_ense2==2 & agno==2016 & inrange(cod_grado, 1, 4)

So, your code might be, if I understand correctly,

egen wanted = max(cod_ense2==2 & agno==2016 & inrange(cod_grado, 1, 4)), by(mrun)

keep if wanted

[Fernando Bastidas]

Thanks so much! It worked!