[R] "Glueing" factors together

[F. Tusell]

Apologies, disregard my former message!  I overlloked the requirement 
that only combinations
present in the data must be taken. ft.

-- 
Fernando TUSELL                                e-mail:
Departamento de Econometría y Estadística           etptupaf at bs.ehu.es 
Facultad de CC.EE. y Empresariales             Tel:   (+34)94.601.3733
Avenida Lendakari Aguirre, 83                  Fax:   (+34)94.601.3754
E-48015 BILBAO  (Spain)                        Secr:  (+34)94.601.3740