R version 2.5.0 Under development (unstable) (2007-03-25 r40887) Copyright (C) 2007 The R Foundation for Statistical Computing ISBN 3-900051-07-0 R is free software and comes with ABSOLUTELY NO WARRANTY. You are welcome to redistribute it under certain conditions. Type 'license()' or 'licence()' for distribution details. R is a collaborative project with many contributors. Type 'contributors()' for more information and 'citation()' on how to cite R or R packages in publications. Type 'demo()' for some demos, 'help()' for on-line help, or 'help.start()' for an HTML browser interface to help. Type 'q()' to quit R. > library("foreign") > df <- read.arff("contact-lenses.arff") > summary(df) age spectacle-prescrip astigmatism tear-prod-rate pre-presbyopic:8 hypermetrope:12 no :12 normal :12 presbyopic :8 myope :12 yes:12 reduced:12 young :8 contact-lenses hard: 4 none:15 soft: 5 > str(df) 'data.frame': 24 obs. of 5 variables: $ age : Factor w/ 3 levels "pre-presbyopic",..: 3 3 3 3 3 3 3 3 1 1 ... $ spectacle-prescrip: Factor w/ 2 levels "hypermetrope",..: 2 2 2 2 1 1 1 1 2 2 ... $ astigmatism : Factor w/ 2 levels "no","yes": 1 1 2 2 1 1 2 2 1 1 ... $ tear-prod-rate : Factor w/ 2 levels "normal","reduced": 2 1 2 1 2 1 2 1 2 1 ... $ contact-lenses : Factor w/ 3 levels "hard","none",..: 2 3 2 1 2 3 2 1 2 3 ... > q()