Do **NOT** use dummy variables in R. R's modeling functions takes care of this themselves using factors. You say you are a beginner. OK, so begin **properly** -- by reading An Introduction to R. Chapter 11 on Statistical Models in R was written precisely to help people like you learn what to do and avoid asking inappropriate questions like this on this list.
Bert Gunter Genentech Nonclinical Biostatistics -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Arantzazu Blanco Bernardeau Sent: Thursday, June 03, 2010 10:04 AM To: bt_jan...@yahoo.de; r-help@r-project.org Subject: Re: [R] Creating dummy variables hey thanks I did solve it already, it had more mistakes as you see :S bye Arantzazu Blanco Bernardeau Dpto de Qummica Agrmcola, Geologma y Edafologma Universidad de Murcia-Campus de Espinardo > Date: Thu, 3 Jun 2010 14:40:30 +0000 > From: bt_jan...@yahoo.de > Subject: AW: [R] Creating dummy variables > To: r-help@r-project.org; aramu...@hotmail.com > > Was that the original code that you ran? As there appear to be several mistakes in the code: > > 1. In the gipsisoil stuff, there is a ')' too much > 2. In the gambisoil stuff both > signs point in the same direction, you probably want one > and one < > > > My general suggestion would be to skip the loops altogether and vectorize your code: > > datos$cambi=datos$codsuelo > datos$cambi[datos$codsuelo>=3.1 && datos$codsuelo <=3.3] <- 1 > > Another source of your error could be that datos$codtipo is not numeric. What does class(datos$codzuelo) say? > > > HTH > Jannis > > for (i in > > 1:length(datos$cambi)){if(datos$codsuelo[i]>=3.1 > > && > > datos$codsuelo[i]>=3.3){datos$cambi[i]=1}else{0} > > } > > --- Arantzazu Blanco Bernardeau <aramu...@hotmail.com> schrieb am Do, 3.6.2010: > > > Von: Arantzazu Blanco Bernardeau <aramu...@hotmail.com> > > Betreff: [R] Creating dummy variables > > An: r-help@r-project.org > > Datum: Donnerstag, 3. Juni, 2010 14:11 Uhr > > > > Hello R project > > I am a R beginner trying to create a dummy variable to > > clasificate soil types. > > So, I have a column in my database called codtipo (typecode > > in english) where soil type is coded as > > 1.1 to 1.4 arenosol (I have 4 types) > > 2.1 to 2.3 calcisols > > 4.1 to 4.4 fluvisols > > and so on > > To make dummy variables I understand that, I create > > different columns as for gipsisols > > datos$gipsi=datos$codsuelo > > for (i in > > 1:length(datos$gipsi)){if(datos$codsuelo[i]>=5.1 > > && > > (datos$codsuelo[i]<=5.4){datos$gipsi[i]=1}else{0} > > } > > for cambisols it should be > > datos$cambi=datos$codsuelo > > for (i in > > 1:length(datos$cambi)){if(datos$codsuelo[i]>=3.1 > > && > > datos$codsuelo[i]>=3.3){datos$cambi[i]=1}else{0} > > } > > and so on... > > but anyway R answers that a necesary value TRUE/FALSE is > > not existing. > > What can I do? > > thanks a lot!! > > > > > > Arantzazu Blanco Bernardeau > > Dpto de Qummica Agrmcola, Geologma y Edafologma > > Universidad de Murcia-Campus de Espinardo > > > > > > > > > > > > > > > > > Date: Thu, 3 Jun 2010 06:51:42 -0700 > > > From: lampria...@yahoo.com > > > To: jorism...@gmail.com > > > CC: r-help@r-project.org > > > Subject: Re: [R] ordinal variables > > > > > > Thank you Joris, > > > I'll have a look into the commands you sent me. They > > look convincing. I hope my students will also see them in a > > positive way (although I can force them to pretend that they > > have a positive attitude)! > > > > > > Dr. Iasonas Lamprianou > > > > > > > > > > > > > > > > > > Assistant Professor (Educational Research and > > Evaluation) > > > > > > Department of Education Sciences > > > > > > European University-Cyprus > > > > > > P.O. Box 22006 > > > > > > 1516 Nicosia > > > > > > Cyprus > > > > > > Tel.: +357-22-713178 > > > > > > Fax: +357-22-590539 > > > > > > > > > > > > > > > > > > Honorary Research Fellow > > > > > > Department of Education > > > > > > The University of Manchester > > > > > > Oxford Road, Manchester M13 9PL, UK > > > > > > Tel. 0044 161 275 3485 > > > > > > iasonas.lampria...@manchester.ac.uk > > > > > > --- On Thu, 3/6/10, Joris Meys <jorism...@gmail.com> > > wrote: > > > > > > From: Joris Meys <jorism...@gmail.com> > > > Subject: Re: [R] ordinal variables > > > To: "Iasonas Lamprianou" <lampria...@yahoo.com> > > > Cc: r-help@r-project.org > > > Date: Thursday, 3 June, 2010, 14:35 > > > > > > see ?factor and ?as.factor. On ordered factors you can > > technically do a spearman without problem, apart from the > > fact that a spearman test by definition cannot give exact > > p-values with ties present. > > > > > > x <- sample(c("a","b","c","d","e"),100,replace=T) > > > > > > y <- sample(c("a","b","c","d","e"),100,replace=T) > > > > > > x.ordered <- > > factor(x,levels=c("e","b","a","d","c"),ordered=T) > > > > > > x.ordered > > > y.ordered <- > > factor(y,levels=c("e","b","a","d","c"),ordered=T) > > > y.ordered > > > > > > cor.test(x.ordered,y.ordered,method="spearman") > > > > > > require(pspearman) > > > > > > spearman.test(x.ordered,y.ordered) > > > > > > R commander has some menu options to deal with > > factors. R commander also provides a scripting window. > > Please do your students a favor, and show them how to use > > those commands. > > > > > > > > > Cheers > > > Joris > > > > > > > > > On Thu, Jun 3, 2010 at 2:25 PM, Iasonas Lamprianou > > <lampria...@yahoo.com> > > wrote: > > > > > > Dear colleagues, > > > > > > > > > > > > I teach statistics using SPSS. I want to use R > > instead. I hit on one problem and I need some quick advice. > > When I want to work with ordinal variables, in SPSS I can > > compute the median or create a barchart or compute a > > spearman correlation with no problems. In R, if I "read" the > > ordinal variable as numeric, then I cannot do a barplot > > because I miss the category names. If I read the variables > > as characters, then I cannot run a spearman. How can I read > > a variable as numeric, still have the chance to assign value > > labels, and be able to get table of frequencies etc? I want > > to be able to do all these things in R commander. My > > students will probable be scared away if I try anything else > > other than R commander (just writing commands will not make > > them happy). > > > > > > > > > > > > > > > I hope I am not asking for too much. Hopefully there > > is a way > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ______________________________________________ > > > > > > R-help@r-project.org > > mailing list > > > > > > https://stat.ethz.ch/mailman/listinfo/r-help > > > > > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > > > > > > and provide commented, minimal, self-contained, > > reproducible code. > > > > > > > > > > > > > > > -- > > > Joris Meys > > > Statistical Consultant > > > > > > Ghent University > > > Faculty of Bioscience Engineering > > > Department of Applied mathematics, biometrics and > > process control > > > > > > > > > Coupure Links 653 > > > B-9000 Gent > > > > > > tel : +32 9 264 59 87 > > > joris.m...@ugent.be > > > > > ------------------------------- > > > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php > > > > > > > > > > > > > > > > > > > > > [[alternative HTML version > > deleted]] > > > > > > ______________________________________________ > > > R-help@r-project.org > > mailing list > > > https://stat.ethz.ch/mailman/listinfo/r-help > > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > > > and provide commented, minimal, self-contained, > > reproducible code. > > > > > > > > > > _________________________________________________________________ > > Citas sin compromiso por Internet Te damos las claves para > > encontrar pareja en la red > > > > [[alternative HTML version deleted]] > > > > > > -----Integrierter Anhang folgt----- > > > > ______________________________________________ > > R-help@r-project.org > > mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, > > reproducible code. > > > > > _________________________________________________________________ Citas sin compromiso por Internet Te damos las claves para encontrar pareja en la red [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
