I advocate not converting to factor in the first place. Delay that until you won't be wanting specific levels to be accounted for. -- Sent from my phone. Please excuse my brevity.
On March 1, 2016 9:33:31 AM PST, David L Carlson <dcarl...@tamu.edu> wrote: >You need to learn how to send emails in plain text since html gets >mangled on r-help. See your message below. If I understand your >question, it has to do with what happens to factor levels when you >subset your data. Subsetting a factor does not remove empty factor >levels. This is documented on the manual page for subset(): > >"Factors may have empty levels after subsetting; unused levels are not >automatically removed. See droplevels for a way to drop all unused >levels from a data frame." > >------------------------------------ >David L Carlson >Department of Anthropology >Texas A&M University >College Station, TX 77840-4352 > > >-----Original Message----- >From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of hoda >rahmati via R-help >Sent: Tuesday, March 1, 2016 10:32 AM >To: r-help@r-project.org >Subject: [R] Fw: removing factor values in the main data frame > >Hi all,I have the following main data frame:(mydata) $ TE : num >40 40 20 20 20 20 20 20 20 40 ... $ TR : num 49 49 28 28 28 28 >28 28 28 49 ... $ COUNTRY : Factor w/ 27 levels >"","AU","BA","BE",..: 8 8 8 8 8 ...among the COUNTRY I just need US and >AU,first I get a subset to contain just these two countries: > submydata=subset(mydata,COUNTRY%in%c("US","AU")) > factor(submydata$COUNTRY) but after this when I get str of mydata >again I have the same data frame with no changes in COUNTRY, however I >want mydata to be like: > $ TE : num 40 40 20 20 20 20 20 20 20 40 ... $ TR : num >49 49 28 28 28 28 28 28 28 49 ... $ COUNTRY : Factor w/ 2 levels >"","AU","US",..: 8 8 8 8 8 8 8 8 8 8Thanks for any help > > > [[alternative HTML version deleted]] > >______________________________________________ >R-help@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. >______________________________________________ >R-help@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@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.
