Using foreach for two set of groups

[Ike Mensah]

Dear All,

I have two groups of countries and pairwise data- importers and exporters. Eg. Importers= ITALY, FRANCE, GERMANY etc. and exporters=ITALY, FRANCE, GERMANY, CHINA, UK, USA etc. Let EMU countries be ITALY, FRANCE, GERMANY

I want to use the "foreach" command or any command to create a new variable say EMU which takes 1 for any pair of EMU countries and 0 otherwise.

Thank you.

[Nick Cox]

I can't see that this is a loop problem at all. How about (some variation on) this?

gen EMU = inlist(importer, "ITALY", "FRANCE", "GERMANY") & inlist(exporter, "ITALY", "FRANCE", "GERMANY")

[Ike Mensah]

Thank you, Prof. Cox. Interestingly, an error reads "too long expression". I have total 15 countries on both sides. I don't seem to understand this error.

gen CET = inlist(Imp_ISO, "BEN", "GHA", "NGA","BFA", "SEN", "CIV","CPV", "GMB", "GIN","GNB", "MLI", "NER", "TGO", "LBR", "SLE") & /*
*/ inlist(Exp_ISO, "BEN", "GHA", "NGA","BFA", "SEN", "CIV","CPV", "GMB", "GIN","GNB", "MLI", "NER", "TGO", "LBR", "SLE")

[Nick Cox]

So, you changed the question to 15 African countries. OK, but if you change the question, the answer might change too. Now you need to read the help

help inlist()

inlist(z,a,b,...)
Description: 1 if z is a member of the remaining arguments; otherwise, 0

All arguments must be reals or all must be strings. The number of arguments is between 2
and 250 for reals and between 2 and 10 for strings.
Domain: all reals or all strings
Range: 0 or 1

and indeed your expression is too long. Try something like

gen CET = (inlist(Imp_ISO, "BEN", "GHA", "NGA","BFA", "SEN", "CIV","CPV", "GMB") | inlist(Imp_ISO, "GIN","GNB", "MLI", "NER", "TGO", "LBR", "SLE")) 
& (inlist(Exp_ISO, "BEN", "GHA", "NGA","BFA", "SEN", "CIV","CPV", "GMB") | inlist(Exp_ISO, "GIN","GNB", "MLI", "NER", "TGO", "LBR", "SLE"))

[Ike Mensah]

Perfect! Works correctly. Thanks, Prof. Cox