This should do what you want -- not sure what happens after the 4th less than 5.
> a <- rep(c(3,5,7), 4) > b <- rep(c(NA,1,2), 4) > df <- data.frame(a,b) > # determine which ones are < 5 and count the occurances > less.5 <- cumsum(df$a < 5) > # create new value > df$c <- ifelse(df$a < 5, (less.5 + 1) %/% 2, df$b) > df a b c 1 3 NA 1 2 5 1 1 3 7 2 2 4 3 NA 1 5 5 1 1 6 7 2 2 7 3 NA 2 8 5 1 1 9 7 2 2 10 3 NA 2 11 5 1 1 12 7 2 2 On Sat, May 3, 2008 at 3:43 PM, Greg Blevins <[EMAIL PROTECTED]> wrote: > Hello, R-helpers. > > I have a data frame below called df. I want to add a variable c, based on > the following logic: > > if df$a < 5 then the first two times this condition is met place a 1 in c, > the next two times this condition is met place a 2 in c and when the > condition is not met let c equal df$b. The result would look like, dfnew, > shown below. > > > a <- rep(c(3,5,7), 4) > b <- rep(c(NA,1,2), 4) > df <- data.frame(a,b) > > > df > a b > 1 3 NA > 2 5 1 > 3 7 2 > 4 3 NA > 5 5 1 > 6 7 2 > 7 3 NA > 8 5 1 > 9 7 2 > 10 3 NA > 11 5 1 > 12 7 2 > > c <- c(1 , 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2) > dfnew <- data.frame(a, b,c) > > dfnew > a b c > 1 3 NA 1 > 2 5 1 1 > 3 7 2 2 > 4 3 NA 1 > 5 5 1 1 > 6 7 2 2 > 7 3 NA 2 > 8 5 1 1 > 9 7 2 2 > 10 3 NA 2 > 11 5 1 1 > 12 7 2 2 > > Thanks > Greg > R 2.7 XP > > -- > Gregory L. Blevins > Office 952 944-5743 > Cell 612 251 0232 > [EMAIL PROTECTED] > > [[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. > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem 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.
