[R] Creating dummy variables
Bert Gunter
gunter.berton at gene.com
Thu Jun 3 19:29:23 CEST 2010
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-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Arantzazu Blanco Bernardeau
Sent: Thursday, June 03, 2010 10:04 AM
To: bt_jannis at yahoo.de; r-help at 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_jannis at yahoo.de
> Subject: AW: [R] Creating dummy variables
> To: r-help at r-project.org; aramucia at 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$cambi[i]=1}else{0}
> > }
>
> --- Arantzazu Blanco Bernardeau <aramucia at hotmail.com> schrieb am Do,
3.6.2010:
>
> > Von: Arantzazu Blanco Bernardeau <aramucia at hotmail.com>
> > Betreff: [R] Creating dummy variables
> > An: r-help at r-project.org
> > Datum: Donnerstag, 3. Juni, 2010 14:11 Uhr
> >
> > Hello R project
> > I am a R beginner trying to create a dummy variable to
> > clasificate soil types.
> > So, I have a column in my database called codtipo (typecode
> > in english) where soil type is coded as
> > 1.1 to 1.4 arenosol (I have 4 types)
> > 2.1 to 2.3 calcisols
> > 4.1 to 4.4 fluvisols
> > and so on
> > To make dummy variables I understand that, I create
> > different columns as for gipsisols
> > datos$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: lamprianou at yahoo.com
> > > To: jorismeys at gmail.com
> > > CC: r-help at 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.lamprianou at manchester.ac.uk
> > >
> > > --- On Thu, 3/6/10, Joris Meys <jorismeys at gmail.com>
> > wrote:
> > >
> > > From: Joris Meys <jorismeys at gmail.com>
> > > Subject: Re: [R] ordinal variables
> > > To: "Iasonas Lamprianou" <lamprianou at yahoo.com>
> > > Cc: r-help at 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
> > <lamprianou at 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 at 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.Meys at Ugent.be
> >
> > > -------------------------------
> > > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
> > >
> > >
> > >
> > >
> > >
> > >
> > > [[alternative HTML version
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> > >
> > > ______________________________________________
> > > R-help at 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
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> >
> > [[alternative HTML version deleted]]
> >
> >
> > -----Integrierter Anhang folgt-----
> >
> > ______________________________________________
> > R-help at 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.
> >
>
>
>
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