Hi again! Please try something like this:
> zone1.df zone sex len 1 1 male 15 2 1 fema 20 3 1 fema 17 4 2 fema 19 5 2 male 18 > str(zone1.df) 'data.frame': 5 obs. of 3 variables: $ zone: Factor w/ 2 levels "1","2": 1 1 1 2 2 $ sex : Factor w/ 2 levels "fema","male": 2 1 1 1 2 $ len : int 15 20 17 19 18 > tapply(zone1.df$len,zone1.df[,-3],mean) sex zone fema male 1 18.5 15 2 19.0 18 > Hope this helps! Sincerely, Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: [EMAIL PROTECTED] From: "Jorge Cornejo-Donoso" <[EMAIL PROTECTED]> To: "'Erin Hodgess'" <[EMAIL PROTECTED]> Subject: RE: [R] RV: by sentence OK.. Thank for the advice. By and tapply works with 1 categorical variable, but what can be used for 2 categorical variables. Example: Zone Sex Length 1 male 15 1 fema 20 1 fema 17 2 fema 19 2 male 18 The idea is to get the means by sex in each zone! Thank in advance! -- Jorge Cornejo Donoso Universidad Austral de Chile ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code. ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.