First of all, what you have will not work since you also have to subset the RHS of the equation:
data$score[data$type=="1" & data$year=="2001"]<-data$score[data$type=="1" & data$year=="2001"] * 0.111 Another way is to construct a matrix of the values you want to search for and change: (not tested) change <- rbind(c(1, 2001, 0.111), c(1, 2002, 0.222), c(1, 2003, 0.333), c(2, 2001, 1.111), .....) for (i in seq(nrow(change))){ select <- data$type == change[i,1] & data$year == change[i,2] data$score[select] <- data$score[select] * change[i,3] } On Fri, Sep 26, 2008 at 6:35 PM, Mark Na <[EMAIL PROTECTED]> wrote: > Hello, > > I would like to be able to update an existing column in a dataframe, like > this... > > data$score[data$type=="1" & data$year=="2001"]<-data$score * 0.111 > data$score[data$type=="1" & data$year=="2002"]<-data$score * 0.222 > data$score[data$type=="1" & data$year=="2003"]<-data$score * 0.333 > > ...but, if possible, using simpler code. I've got several dozen lines of > code like this (type 2, type3, etc. for the same years) so it would be great > if I could reduce each set of three lines of code to one line > > Any help much appreciated, thanks! > > Mark > > ______________________________________________ > 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.