with() would seem to be useful here: m$z <- with(m,ifelse(is.na(z), x, z))
(I believe the timing is similar, but haven't checked) -- Bert On Wed, Sep 8, 2010 at 11:22 AM, Dimitris Rizopoulos <d.rizopou...@erasmusmc.nl> wrote: > one way is the following: > > m <- data.frame(x = rnorm(100), y = rnorm(100), z = rnorm(100)) > m$z[sample(100, 20)] <- NA > > m$z.new <- ifelse(is.na(m$z), m$x, m$z) > > > I hope it helps. > > Best, > Dimitris > > > On 9/8/2010 8:17 PM, Jakob Hedegaard wrote: >> >> Hi list, >> >> I have a data frame (m) with 169221 rows and 10 columns and would like to >> make a new column containing the content of column 3 but replace the NAs in >> column 3 with the data in column 1 (from the same row as the NA in column >> 3). Column 1 has data in all rows. >> >> My first attempt was: >> >> for (i in 1:169221){ >> if (is.na(m[i,3])==TRUE){ >> m[i,11]<- as.character(m[i,1])} >> else{ >> m[i,11]<- as.character(m[i,3])} >> } >> >> Works - but takes too long time. >> I would appreciate alternative solutions. >> >> Best regards, Jakob >> >> ______________________________________________ >> 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. >> > > -- > Dimitris Rizopoulos > Assistant Professor > Department of Biostatistics > Erasmus University Medical Center > > Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands > Tel: +31/(0)10/7043478 > Fax: +31/(0)10/7043014 > > ______________________________________________ > 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. > ______________________________________________ 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.