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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: AW: RE: AW: RE: combination foreach forvalues |

Date |
Tue, 20 Oct 2009 13:58:43 +0200 |

<> John may also want to look at Nick`s Sj tip re "special sequences": http://www.stata-journal.com/sjpdf.html?articlenum=pr0013 HTH Martin -----Ursprüngliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Nick Cox Gesendet: Dienstag, 20. Oktober 2009 13:48 An: statalist@hsphsun2.harvard.edu Betreff: st: RE: AW: RE: combination foreach forvalues -encode- by default returns a mapping that is strictly alphabetical. As this is what John is asking for, that is not obviously problematic. In any case, -encode- allows you to specify a set of labels to be used. What you may be referring to is that sometimes users want encoding in order of first occurrence in the data. That can be tackled in various ways, but John doesn't mention this. However, it is easy to imagine that if some of the letters a ... z do not occur in practice, then a straight -encode- may not be what John wants. Consider this: tokenize "`c(alpha)'" forval i = 1/26 { label def alphabetic `i' "``i''", modify } encode stringvar, gen(numvar) label(alphabetic) More complicated alphabets e.g. with accents or diacritical marks clearly require modified code. Nick n.j.cox@durham.ac.uk Martin Weiss "-encode- does precisely this." I remember there being an issue with the order of the codes that -encode- assigns, that is why I was reluctant to recommend it. Is that not an issue here? Nick Cox This doesn't require either -foreach- or -forvalues-. -encode- does precisely this. Alternatively, bysort stringvar : gen newvar = _n == 1 replace stringvar = sum(stringvar) or egen newvar = group(stringvar) There is not much to explain about combining -foreach- and -forvalues-, as you just do it if and when you need it, typically by nesting one inside the other. But that's not the case here. John Bunge I have a string variable x1 with a list of values. I want to create a numerical variable x2 in which the numbers correspond to the string values in x1 in an ordered fashion (as a counter). To illustrate, lets assume x1 contains all letters of the alphabet, and I want x2 to contain a counter that corresponds to the position of the letter in the alphabet, i.e. x1=a > x2=1, x1=b > x2=2, x1=c > x2=3, etc... This seems to me like a combination of foreach and forvalues, but I cannot find information on whether and how such thing is implementable in Stata. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: combination foreach forvalues***From:*John Bunge <jota.be@web.de>

**st: RE: combination foreach forvalues***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**st: AW: RE: combination foreach forvalues***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**st: RE: AW: RE: combination foreach forvalues***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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