Preface to First Edition - lib

166 RECURSIVE PARTITIONINGR> library("partykit")R> plot(as.party(bodyfat_rpart), tp_args = list(id = FALSE))1waistcirc2hipcirc< 88.4 >= 88.49kneebreadth< 96.25 >= 96.25< 11.15 >= 11.153610agewaistcirchipcirc< 59.5 >= 59.5< 80.75 >= 80.75< 109.9 >= 109.9n = 11n = 6n = 13n = 10n = 13n = 15n = 3605040302010605040302010605040302010605040302010605040302010605040302010605040302010Figure 9.1Initial tree for the body fat data with the distribution of body fat interminal nodes visualised via boxplots.To determine if the tree is appropriate or if some of the branches need tobe subjected to pruning we can use the cptable element of the rpart object:R> print(bodyfat_rpart$cptable)CP nsplit rel error xerror xstd1 0.66289544 0 1.00000000 1.0270918 0.168404242 0.09376252 1 0.33710456 0.4273989 0.094300243 0.07703606 2 0.24334204 0.4449342 0.086861504 0.04507506 3 0.16630598 0.3535449 0.069570805 0.01844561 4 0.12123092 0.2642626 0.059745756 0.01818982 5 0.10278532 0.2855892 0.062213937 0.01000000 6 0.08459549 0.2785367 0.06242559R> opt cp bodyfat_prune