How to store values of a variable in a local macro

[Krishanu Karmakar]

Dear Statalist,

I am running Stata 12.1 on Windows 7, Home Premium,

I have a str3 variable "country" which has three unique values (many observations): ABC, DEF, GHI.

I want to store the three string values ABC, DEF and GHI in a local macro "countrylist" for further use. Right now I am entering them into the local macro manually, but later I may add more data to my current dataset and then the string variable "country" will have more unique values than just three. I do not want to rewrite the do file again. Is there some way to automatically enter the unique values of the variable "country" into the local macro "countrylist"?

Right now my code looks like the following

input str3 country var1 var2
ABC    5    7
DEF 6    8
GHI 2    3
ABC    1    8
DEF 0    9
GHI 1    4
ABC    4    5
DEF 3    3
GHI 5    2
end

local countrylist ABC DEF GHI

foreach country of local countrylist{
                 reg var1 var2 if country == "`country'"
                 predict var1_hat if country == "`country'"
}

Thank you.

[Nick Cox]

This is what levelsof does.

For "unique" read "distinct".

Nevertheless, see http://www.stata.com/support/faqs/da...ach/index.html for other approaches.

[Krishanu Karmakar]

Thank you Dr. Cox.

[Nick Cox]

Notice also that your loop would fail second time around as then var1_hat already exists.

gen var1_hat = .  
foreach country of local countrylist {
     reg var1 var2 if country == "`country'"    
     predict work if country == "`country'"    
     replace var1_hat = work if country == "`country'"      
     drop work  
}

[Krishanu Karmakar]

Yes it did, then I corrected that line in my do file.