Dear Kristina, Use ifelse(). Note that you must use '==' to test for equality. '=' is an assignment.
Freqg$condition <- with(freqg, ifelse(mat==1 & flank==1, 1, ifelse(mat == 2 & flank == 1, 2, NA))) HTH, Thierry ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek team Biometrie & Kwaliteitszorg Gaverstraat 4 9500 Geraardsbergen Belgium Research Institute for Nature and Forest team Biometrics & Quality Assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 thierry.onkel...@inbo.be www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey > -----Oorspronkelijk bericht----- > Van: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] Namens Kristina Schmitz > Verzonden: donderdag 27 mei 2010 11:33 > Aan: r-help@r-project.org > Onderwerp: [R] adding column to data frame conditionally > > Dear all and thanks in advance for helping me with a rather > stupid question: > I imported a data set ("freqg") into R consisting of 14 > variables. Now a want to compute a variable and add it in an > additional column to my data frame. The value of this new > variable ("condition") depends on the values of two other > variables ("mat" and "flank") already included in the data frame. > For example: > if mat=1 and flank=1 -> condition=1 > if mat=2 and flank=1 -> condition=2 > ... > > What I got is this code, which doesn't really work (it > results in a new column called "condition" which takes only > the value "TRUE"): > > freqg<-transform(freqg,condition=(mat=1)&(flank=1)) > > Thanks in advance and kind regards! > > ______________________________________________ > 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. > Druk dit bericht a.u.b. niet onnodig af. Please do not print this message unnecessarily. Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document. The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document. ______________________________________________ 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.
