Dear Profs and colleagues,

I am going to generate a variable that shows how many export varieties firms export.
Firm ID: NPC_FIC
Commodity Code: artigo
Type of trade (Export =2, Import=1): fluxo



Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input double NPC_FIC str10 fluxo str24 artigo
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
10006 "Exporta��o" "01012990"
500000001 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000002 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000033 ""           ""        
500000050 ""           ""        
500000050 ""           ""        
500000050 ""           ""        
500000050 ""           ""        
500000050 ""           ""        
500000050 ""           ""        
500000069 ""           ""        
500000069 ""           ""        
500000073 ""           ""        
500000073 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000083 ""           ""        
500000101 ""           ""        
500000101 ""           ""        
500000101 ""           ""        
500000101 ""           ""        
500000101 ""           ""        
500000101 ""           ""        
500000104 ""           ""        
500000106 ""           ""        
500000113 ""           ""        
500000113 ""           ""        
500000113 ""           ""        
500000113 ""           ""        
500000119 "Exporta��o" "07019090"
500000119 "Exporta��o" "07019090"
500000119 "Exporta��o" "07019090"
500000119 "Exporta��o" "07019090"
500000119 "Importa��o" "07019090"
500000119 "Importa��o" "07019090"
500000119 "Importa��o" "07019090"
500000119 "Importa��o" "07019090"
500000119 "Importa��o" "07019090"
Starting with :

Code:
by NPC_FIC fluxo (artigo), sort: gen n_ex = sum(artigo != artigo[_n-1])
by NPC_FIC fluxo (artigo): replace n_ex = n_ex[_N]
Could you please help me to finish that?

Cheers,
Paris