Dear all, I have a data.frame which has names as following. [1] "XG1" "YG1" "XEST" "YEST" [2] "XNOEMP1" "XNOEMP2" "YNOEMP1" "YNOEMP2" [3] "XBUS10" "XBUS10A" "XBUS10B" "XBUS10C" [4] "YBUS10" "YBUS10A" "YBUS10B" "YBUS10C" [5] "XOWNBUS" "XSELFEST" "YOWNBUS" "YSELFEST"
Those columns have names beginning with "X" or "Y". Each "X" is paired by a "Y", e.g. "XG1" and "YG1", but they are not in the order of "X Y X Y ...". I want to combine "X*" and "Y*" like this: data.new[,"G1"] <- (data.old[,"XG1"] + endata.use[,"YG1"])/2 How to choose columns by parts of names? For example, I can pick out XG1 and YG1 because they have the common part "G1". Thank you. Wei-Wei ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html