Re: [Gretl-users] Computing an index for unique combinations of discrete variables

On Thu, 21 Nov 2013, Giuseppe Vittucci wrote: > Hi, > > I have firm level data and two categorical variables (region and > sector). > I need to define another variable which is an index identifying the > unique combinations region-sector each firm belongs to, so I can use it > in computing cluster-robust s.e. > > One way to do this is to use the command "values" for region and sector > and then use a nested loop, but this seems quite time-consuming... > > Is there a simpler way in gretl to do it? You mean, like this? <hansl> nulldata 1024 # simulated data region = randgen(i,1,20) sector = randgen(i,10,99) # ---------------------------------------------- scalar ndigits = floor(log10(max(sector))) series unique = region * 10^(ndigits+1) + sector </hansl> ------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti ------------------------------------------------------- _______________________________________________ Gretl-users mailing list Gretl-users(a)lists.wfu.edu http://lists.wfu.edu/mailman/listinfo/gretl-users