Re: [Gretl-users] dummify with list and script output window

On Sun, 30 Dec 2012, Allin Cottrell wrote: > With regard to dummify, I'm not sure that accepting a list argument > is a great idea, since a (single) series argument already produces a > list result. Producing a "list of lists" seems to me on the verge of > being out of control. Partially OT: I'm asking myself if we should go back to an idea that we briefly considered when we introduced operators for lists, and ended up being put on hold. The idea is to use the "*" operator for a specialised version of the Cartesian product, commony known among applied economists as "interaction" variables. To be more explicit: suppose you have two lists, X and Y, with the only requirement that X should contain discrete variables only. Then, the construct "X*Y" would perform what is accomplished through the following script. <hansl> open keane.gdt list X = choice status list Y = wage educ loop foreach j X --quiet matrix v = values($j) scalar n = rows(v) loop foreach i Y --quiet loop for k=1..n --quiet xi = v[k] sprintf vname "$i_$j_%d", xi series @vname = ($j == xi)*$i end loop end loop end loop </hansl> Note that the dummify command/function would be a special case of this for "Y=const". I have the feeling that people working with micro data would love this. Thoughts? ------------------------------------------------------- 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