问10折交叉验证-函数问题

EN

library(MASS)

tenfold3 = function() {

  fold = 10
  end = nrow(birthwt)
  fold_2 = floor(end/fold)

  misclasrate=numeric()

  for(i in 1:10){

    df_i = birthwt[sample(nrow(birthwt)),] # random sort the dataframe birthwt

    tester = df_i[1:fold_2,]  # remove first tenth of rows - USE PREDICT ON THIS DATA
    trainer = df_i[-c(1:fold_2),]  # all other than the first tenth of rows - USE GLM ON THIS DATA

    #mod = glm(low~age,family=binomial,data=trainer)

    mod = glm(low~age+lwt+race+smoke+ptl+ht+ui+ftv,family=binomial,data=trainer)
    ypred = predict(mod,data=tester,type='response')
    ypred = trunc(0.5+predict(mod,data=tester,type='response')) # predicted values

    val_df = data.frame(trainer[,1],ypred) 
    names(val_df) = c('train','ypred')

    val_df$misclas = (val_df$train == val_df$ypred)
    misclasrate[i] = 1-sum(val_df$misclas) / nrow(val_df)
    mean_mrate = signif(mean(misclasrate),4)
    g = cbind(misclasrate[i],mean_mrate)
    return(mean_mrate)

  }

}