交叉验证

null交 叉 验 证交 叉 验 证以cars数据为例以cars数据为例attach(cars) head(cars) summary(lm(dist~speed,cars)) n<-nrow(cars) s<-sample(1:n,round(n/2)) traindata<-cars[s,] testdata<-cars[-s,] nullsummary(lm.tr<-lm(dist~speed,traindata)) ptedist.lm<-predict(lm.tr,testdata) ptrdist.lm<-predict(lm.tr,traindata) temse<-sum(ptedist.lm-testdata$dist)^2/nrow(testdata) trmse<- sum(ptrdist.lm-traindata$dist)^2/nrow(traindata) nls.tr <- nls(log(dist) ~ xmid*log(speed),data=traindata,start=list(xmid=0)) nls.tr<- nls(log(dist) ~ log(xmid*speed),data=traindata,start=list(xmid=0.1)) summary(nls.tr)nullptedist.nls<-predict(nls.tr,testdata) ptrdist.nls<-predict(nls.tr,traindata) temse<-sum(ptedist.nls-testdata$dist)^2/nrow(testdata) trmse<- sum(ptrdist.nls-traindata$dist)^2/nrow(traindata) 训练集合测试集交换 nullnullnull