Stats 202 - Lecture 7

79012346 020987654 2 start85 62 6 absent 090322581

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Unformatted text preview: * 9) Start< 13.5 23 2 absent (0.91304348 0.08695652) * 5) Age=middle 14 4 absent (0.71428571 0.28571429) 10) Start>=12.5 10 1 absent (0.90000000 0.10000000) * 11) Start< 12.5 4 1 present (0.25000000 0.75000000) * 3) Start< 8.5 19 8 present (0.42105263 0.57894737) 6) Start< 4 10 4 absent (0.60000000 0.40000000) 12) Number< 2.5 1 0 absent (1.00000000 0.00000000) * 13) Number>=2.5 9 4 absent (0.55555556 0.44444444) * 7) Start>=4 9 2 present (0.22222222 0.77777778) 14) Number< 3.5 2 0 absent (1.00000000 0.00000000) * 15 In class exercise #25: Use rpart() in R to fit a decision tree to last column of the sonar training data at http://sites.google.com/site/stats202/data/sonar_train.csv Use all the default values. Compute the misclassification error on the training data and also on the test data at http://sites.google.com/site/stats202/data/sonar_test.csv 16 In class exercise #25: Use rpart() in R to fit a decision tree to last column of the sonar training data at http://sites.google.com/site/stats202/data/sonar_train.csv Use all the default values. Compute the misclassification error on the training data and also on the test data at http://sites.google.com/site/stats202/data/sonar_test.csv Solution: install.packages("rpart") library(rpart) train<-read.csv("sonar_train.csv",header=FALSE) y<-as.factor(train[,61]) x<-train[,1:60] fit<-rpart(y~.,x) sum(y!=predict(fit,x,type="class"))/length(y) 17 In class exercise #25: Use rpart() in R to fit a decision tree to last column of the sonar training data at http://sites.google.com/site/stats202/data/sonar_train.csv Use all the default values. Compute the misclassification error on the training data and also on the test data at http://sites.google.com/site/stats202/data/sonar_test.csv Solution (continued): test<-read.csv("sonar_test.csv",header=FALSE) y_test<-as.factor(test[,61]) x_test<-test[,1:60] sum(y_test!=predict(fit,x_test,type="class"))/ (y_...
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