Just commenting on the email subject, not the content (which you have already been helped with): there is no need to *ever* create a dummy variable for regression in R if what you mean by this is what is conventionally meant. R will create the model matrix with appropriate "dummy variables" for factors as needed. See ?contrasts and ?C for relevant details and/or consult an appropriate R tutorial. Of course, if this is not what you meant, than ignore. Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Fri, Aug 5, 2016 at 1:49 PM, <ruipbarradas at sapo.pt> wrote:> Hello, > > Your ifelse will never work because > reasons$salutation== "Mr" & reasons$salutation=="Father" is always FALSE > and so is reasons$salutation=="Mrs" & reasons$salutation=="Miss". > Try instead | (or), not & (and). > > Hope this helps, > > Rui Barradas > > > > Citando Shivi Bhatia <shivipmp82 at gmail.com>: > >> Dear Team, >> >> I need help with the below code in R: >> >> gender_rec<- c('Dr','Father','Mr'=1, 'Miss','MS','Mrs'=2, 3) >> >> reasons$salutation<- gender_rec[reasons$salutation]. >> >> This code gives me the correct output but it overwrites the >> reason$salutation variable. I need to create a new variable gender to >> capture gender details and leave salutation as it is. >> >> i tried the below syntax but it is converting all to 1. >> >> reasons$gender<- ifelse(reasons$salutation== "Mr" & reasons$salutation=>> "Father","Male", ifelse(reasons$salutation=="Mrs" & reasons$salutation=>> "Miss","Female",1)) >> >> Please suggest. >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.htmland provide commented, >> minimal, self-contained, reproducible code. > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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.
Thanks you all for the assistance. This really helps. Hi Bert: While searching nabble i got to know R with factors variables there is no need to create dummy variable. However please consider this situation: I am in the process of building a logistic regression model on NPS data. The outcome variable is CE i.e. customer experience which has 3 rating so ordinal logistic regression will be used. However most of my variables are categorical. For instance one of the variable is agent knowledge which is a 10 point scale. This agent knowledge is again a 3 rated scale: high medium low hence i need to group these 10 values into 3 groups & then as you suggested i can directly enter them in the model without creating n-1 categories. I have worked on SAS extensively hence found this a bit confusing. Thanks for the help. On Sat, Aug 6, 2016 at 2:30 AM, Bert Gunter <bgunter.4567 at gmail.com> wrote:> Just commenting on the email subject, not the content (which you have > already been helped with): there is no need to *ever* create a dummy > variable for regression in R if what you mean by this is what is > conventionally meant. R will create the model matrix with appropriate > "dummy variables" for factors as needed. See ?contrasts and ?C for > relevant details and/or consult an appropriate R tutorial. > > Of course, if this is not what you meant, than ignore. > > Cheers, > Bert > > > Bert Gunter > > "The trouble with having an open mind is that people keep coming along > and sticking things into it." > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > > On Fri, Aug 5, 2016 at 1:49 PM, <ruipbarradas at sapo.pt> wrote: > > Hello, > > > > Your ifelse will never work because > > reasons$salutation== "Mr" & reasons$salutation=="Father" is always FALSE > > and so is reasons$salutation=="Mrs" & reasons$salutation=="Miss". > > Try instead | (or), not & (and). > > > > Hope this helps, > > > > Rui Barradas > > > > > > > > Citando Shivi Bhatia <shivipmp82 at gmail.com>: > > > >> Dear Team, > >> > >> I need help with the below code in R: > >> > >> gender_rec<- c('Dr','Father','Mr'=1, 'Miss','MS','Mrs'=2, 3) > >> > >> reasons$salutation<- gender_rec[reasons$salutation]. > >> > >> This code gives me the correct output but it overwrites the > >> reason$salutation variable. I need to create a new variable gender to > >> capture gender details and leave salutation as it is. > >> > >> i tried the below syntax but it is converting all to 1. > >> > >> reasons$gender<- ifelse(reasons$salutation== "Mr" & reasons$salutation=> >> "Father","Male", ifelse(reasons$salutation=="Mrs" & > reasons$salutation=> >> "Miss","Female",1)) > >> > >> Please suggest. > >> > >> [[alternative HTML version deleted]] > >> > >> ______________________________________________ > >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > >> https://stat.ethz.ch/mailman/listinfo/r-help > >> PLEASE do read the posting guide > >> http://www.R-project.org/posting-guide.htmland provide commented, > >> minimal, self-contained, reproducible code. > > > > > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > > 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. >[[alternative HTML version deleted]]
Something like:
d = data.frame(score = sample(1:10, 100, replace=TRUE))
d$score_t = "low"
d$score_t[d$score > 3] = "medium"
d$score_t[d$score >7 ] = "high"
d$score_t = factor(d$score_t, levels = c("low", "medium",
"high"),
ordered=TRUE) #set ordered = FALSE for dummy variables
X = model.matrix(~score_t, data=d)
X
On Fri, Aug 5, 2016 at 3:23 PM, Shivi Bhatia <shivipmp82 at gmail.com>
wrote:
> Thanks you all for the assistance. This really helps.
>
> Hi Bert: While searching nabble i got to know R with factors variables
> there is no need to create dummy variable. However please consider this
> situation:
> I am in the process of building a logistic regression model on NPS data.
> The outcome variable is CE i.e. customer experience which has 3 rating so
> ordinal logistic regression will be used. However most of my variables are
> categorical. For instance one of the variable is agent knowledge which is a
> 10 point scale.
>
> This agent knowledge is again a 3 rated scale: high medium low hence i need
> to group these 10 values into 3 groups & then as you suggested i can
> directly enter them in the model without creating n-1 categories.
>
> I have worked on SAS extensively hence found this a bit confusing.
>
> Thanks for the help.
>
> On Sat, Aug 6, 2016 at 2:30 AM, Bert Gunter <bgunter.4567 at
gmail.com>
> wrote:
>
> > Just commenting on the email subject, not the content (which you have
> > already been helped with): there is no need to *ever* create a dummy
> > variable for regression in R if what you mean by this is what is
> > conventionally meant. R will create the model matrix with appropriate
> > "dummy variables" for factors as needed. See ?contrasts and
?C for
> > relevant details and/or consult an appropriate R tutorial.
> >
> > Of course, if this is not what you meant, than ignore.
> >
> > Cheers,
> > Bert
> >
> >
> > Bert Gunter
> >
> > "The trouble with having an open mind is that people keep coming
along
> > and sticking things into it."
> > -- Opus (aka Berkeley Breathed in his "Bloom County" comic
strip )
> >
> >
> > On Fri, Aug 5, 2016 at 1:49 PM, <ruipbarradas at sapo.pt>
wrote:
> > > Hello,
> > >
> > > Your ifelse will never work because
> > > reasons$salutation== "Mr" &
reasons$salutation=="Father" is always
> FALSE
> > > and so is reasons$salutation=="Mrs" &
reasons$salutation=="Miss".
> > > Try instead | (or), not & (and).
> > >
> > > Hope this helps,
> > >
> > > Rui Barradas
> > >
> > >
> > >
> > > Citando Shivi Bhatia <shivipmp82 at gmail.com>:
> > >
> > >> Dear Team,
> > >>
> > >> I need help with the below code in R:
> > >>
> > >> gender_rec<-
c('Dr','Father','Mr'=1,
'Miss','MS','Mrs'=2, 3)
> > >>
> > >> reasons$salutation<- gender_rec[reasons$salutation].
> > >>
> > >> This code gives me the correct output but it overwrites the
> > >> reason$salutation variable. I need to create a new variable
gender to
> > >> capture gender details and leave salutation as it is.
> > >>
> > >> i tried the below syntax but it is converting all to 1.
> > >>
> > >> reasons$gender<- ifelse(reasons$salutation==
"Mr" &
> reasons$salutation=> > >> "Father","Male",
ifelse(reasons$salutation=="Mrs" &
> > reasons$salutation=> > >>
"Miss","Female",1))
> > >>
> > >> Please suggest.
> > >>
> > >> [[alternative HTML version deleted]]
> > >>
> > >> ______________________________________________
> > >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and
more, see
> > >> https://stat.ethz.ch/mailman/listinfo/r-help
> > >> PLEASE do read the posting guide
> > >> http://www.R-project.org/posting-guide.htmland provide
commented,
> > >> minimal, self-contained, reproducible code.
> > >
> > >
> > >
> > > [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more,
see
> > > 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.
> >
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>
[[alternative HTML version deleted]]