[Gretl-devel] String-valued series encoding

Hi all, I've had a recurring problem with string-valued series, and I'm struggling to find a solution. Suppose you have two or more string-valued series that you get from a csv or Stata file, and that they represent comparable variables, so they contain the same strings. Currently, we encode string-valued series by creating string arrays that get filled by occurrence; this, however, impleis that there is no guarantee that the correspondence between internal numerical values and strings is the same for the different series. This makes it awkward to read the output from commands such as freq or xtab. Writing a script to correct for that has proven quite difficult, and what I was able to come up with is VERY far from elegant. An example script follows, and suggestions are much appreciated. <hansl> set verbose off function series string_reorder(strings new, series x) strings ss = strvals(x) n = nelem(ss) m = nelem(new) series tmp = NA loop i = 1 .. n --quiet si = ss[i] k = 0 loop j = 1 .. m --quiet if si == new[j] k = j break endif endloop if k>0 # found tmp = (x == si) ? k : tmp endif endloop return tmp end function clear set verbose off outfile &quot;(a)dotdir/tmp.csv&quot; printf "var1,var2,var3\n" printf "a,b,c\na,c,b\nb,b,b\nc,a,b\na,b,c\na,c,c" end outfile open &quot;(a)dotdir/tmp.csv&quot; --quiet print var1 var2 --byobs xtab var1 var2 # no good # record encoding for var1 ss = strvals(var1) # note: you can't just assign to var2 var2new = string_reorder(ss, var2) stringify(var2new, ss) delete var2 rename var2new var2 # values are the same, but the encoding is reordered print var1 var2 --byobs xtab var1 var2 # better </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 -------------------------------------------------------