pmax() should work even without the fancy stuff. However, as Petr pointed out, so should the ifelse construct, unless there is more to the issue than we have been told. So I think Jennifer needs to elaborate on the "didn't work" aspect...
-pd On 26 Oct 2015, at 13:02 , Erich Neuwirth <erich.neuwi...@univie.ac.at> wrote: > data <- within(data,variable3=pmax(variable1,variable2)) > also should work if your variables are numeric. > > using dplyr and magrittr (which I recommend to all my students) > it could be > > library(dplyr) > library(magrittr) > data %<>% mutate(variable3=pmax(variable1,variable2)) > > > >> On 26 Oct 2015, at 12:53, PIKAL Petr <petr.pi...@precheza.cz> wrote: >> >> Hi >> >>> -----Original Message----- >>> From: R-help [mailto:r-help-boun...@r-project.org >>> <mailto:r-help-boun...@r-project.org>] On Behalf Of Duncan >>> Murdoch >>> Sent: Monday, October 26, 2015 11:58 AM >>> To: Lorenz, Jennifer; r-help@r-project.org <mailto:r-help@r-project.org> >>> Subject: Re: [R] Creating new variables in R >>> >>> On 26/10/2015 6:24 AM, Lorenz, Jennifer wrote: >>>> Hi, >>>> >>>> I have a question regarding the creation of new variables on the >>> basis of existing ones in R. >>>> >>>> I have two variables containing information on parents' educational >>> degree (e.g. 1 'high school degree', 2 'college degree', etc.). I would >>> like to create a new variable for 'parents' highest educational >>> degree', i.e. if variable1 (father's degree) is higher than variable2 >>> (mother's degree) than the new variable (variable3) should take on the >>> value of variable1, if not, than variable3 should take on the value of >>> variable2. >>>> >>>> I usually use SPSS for data manipulation, there I would code >>> variable3 as follows: >>>> COMPUTE variable3= 0. >>>> IF variable1 > variable2 variable3= variable1. >>>> IF variable1 <= variable2 variable3= variable2. >>>> >>>> The closest I came to that in R was with this code: >>>> data$variable3 <- 0 >>>> data$variable3[data$variable1 > data$variable2]<-data$variable1 >>>> data$variable3[data$variable1 <= data$variable2]<-data$variable2 >>>> >>>> I also tried: >>>> data$variable3 <- ifelse(data$variable1 > data$variable2), >>>> data$variable1, data$variable2) >>>> >>>> Both didn't work. >> >> The ifelse version should work. Are you sure that variable 1 and 2 are >> numeric?. >> >> What is a result of str(data)? >> >> Cheers >> Petr >> >>>> >>>> I am not sure if my post is at all understandable (this is my first >>> time posting on R-help), but I am really hoping for some advice! >>> >>> This is a good place to use the ifelse() function: >>> >>> data$variable3 <- ifelse(data$variable1 > data$variable2, >>> data$variable1, data$variable2) >>> >>> Duncan Murdoch >>> >>> ______________________________________________ >>> 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. >> >> ________________________________ >> Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a jsou >> určeny pouze jeho adresátům. >> Jestliže jste obdržel(a) tento e-mail omylem, informujte laskavě neprodleně >> jeho odesílatele. 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