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

Hi, I'm of the opinion that a "*" operator for interaction variables is a very useful means! A few weeks ago we discussed such possibilities in terms of MANOVA. This would be the solution to such problems of descriptive statistics and further analysis. What should be achieved? Well, I think list creation and usage in a model command like "dummify" now. Would be great if this functionality would be implemented! Have nice weekend Leon Am 30.12.2012 13:15, schrieb Riccardo (Jack) Lucchetti: > 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