ifelse worked like a charm for this newbie. Thanks, Dennis! -Frank
On Feb 14, 2011, at 3:39 AM, Dennis Murphy wrote: > Hi: > > Wouldn't ifelse() work here? > > tco <- with(df, ifelse(TargetColor == 'B', CannonOriB, CannonOriR)) > > ifelse() is vectorized, so there should be no need for a loop. > > Test: > > df <- data.table(TargetColor = c('B', 'R'), CannonOriB = c(5, 5), > + CannonOriR = c(3, 3), stringsAsFactors = FALSE) > > with(df, ifelse(TargetColor == 'B', CannonOriB, CannonOriR)) > [1] 5 3 > > HTH, > Dennis > > On Mon, Feb 14, 2011 at 1:02 AM, Frank Tamborello > <franklin.tambore...@uth.tmc.edu> wrote: > Dear R-Help, > > I am trying to compute a new variable, let's call it "target cannon > orientation (tco)" based conditionally on old variables, "TargetColor," > "CannonOriB," and "CannonOriR." For every case in the data set, if > TargetColor is "B" then I want tco to equal the value for that case of > CannonOirB, else CannonOriR. I've tried writing for loops and functions that > I can feed to sapply. I suspect there must be a simple solution but I cannot > seem to get either incantation to perform the assignment. What would be a > good way to do this? > > Example data: > TargetColor.1.18 CannonOriB.1.18 "CannonOriR.1.1 > "B" 5 3 > "R" 5 3 > > > Example assignment of tco > "tco" > 5 > 3 > > Thanks much! > > Frank Tamborello, PhD > W. M. Keck Postdoctoral Fellow > School of Biomedical Informatics > University of Texas Health Science Center, Houston > https://xfiles.uth.tmc.edu/Users/ftamborello/public/index.html > > ______________________________________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.