use ifelse: > DF <- data.frame(cbind(a=1:4, b=1:2, c=1:8, d=1:16, e=0, f=0)) > DF$Test <- with(DF, a == b) > > DF$e = (DF$c*DF$d) * DF$Test + (DF$c+DF$d) * !DF$Test > > DF$f = with(DF, (c*d)*Test + (c+d)*!Test) > #or > DF$f.1 <- ifelse(DF$Test, DF$c * DF$d, DF$c + DF$d) > head(DF) a b c d e f Test f.1 1 1 1 1 1 1 1 TRUE 1 2 2 2 2 2 4 4 TRUE 4 3 3 1 3 3 6 6 FALSE 6 4 4 2 4 4 8 8 FALSE 8 5 1 1 5 5 25 25 TRUE 25 6 2 2 6 6 36 36 TRUE 36 >
On Sun, Jul 19, 2009 at 5:17 PM, Mark Knecht<markkne...@gmail.com> wrote: > Hi, > In my data.frame I wanted to essentially write > > If(Test) c*d else c+d > > but that doesn't work. I found I could do it mathematically, but it > seems forced and won't scale well for nested logic. I have two > examples below writing columns e & f, but I don't think the code is > self-documenting as it depends on knowing that Test is a TRUE/FALSE. > > Is there a better way to do the following? > > Thanks, > Mark > > > DF <- data.frame(cbind(a=1:4, b=1:2, c=1:8, d=1:16, e=0, f=0)) > DF$Test <- with(DF, a == b) > > DF$e = (DF$c*DF$d) * DF$Test + (DF$c+DF$d) * !DF$Test > > DF$f = with(DF, (c*d)*Test + (c+d)*!Test) > > DF > > ______________________________________________ > 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. > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? ______________________________________________ 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.
