Hello, I suppose this is a basic question but couldn't find a solution.:
I have a large matrix with let say 3 columns: V1 V2 V3 a x 2 a x 4 a y 8 b z 16 and I want to compute some statistics based on the levels resulting form the combination of the two first columns e.g.: SUM-> V1 V2 V3 a x 6 a y 8 b z 16 Thanks for your hints . Marc ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
