Hello to anyone who is still reading this, I am working with elections data in which I have the votes a candidate received but not if they won or not. I want to add a couple columns to my dataset just noting if the candidate won and by how much. I feel like this should be easy. And yet… Here is what I've done length(unique(data$constituency)) mat<-as.vector(unique(data$constituency)) for(i in 1:229){ sub<-data[data$constituency==mat[i],] ordered<-sub[order(sub[,"vote"], decreasing=TRUE),] win<-ordered[1,] second<-ordered[2,] totalvotes<-sum(sub[,"vote"]) winvote<-win[,"vote"] secvote<-second[,"vote"] margin<-winvote-secvote pcntmarg<-as.numeric(margin/totalvotes) data[data[,"name"]==win[,"name"],]$marginwin[]<-pcntmarg data[data[,"name"]==win[,"name"],]$elected[]<-1 } Resulting in these errors: Error in `$<-.data.frame`(`*tmp*`, "marginwin", value = numeric(0)) : replacement has 0 rows, data has 1 Any words of wisdom? Thanks from Ghana!! Julie _______________________________________________ gov2001-l mailing list gov2001-l(a)lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l