r - 机器学习中具有 10 倍交叉验证的代码

Question

我刚刚开始从事机器学习工作。我尝试使用 C5.0 模型运行 10 折交叉验证。我要求代码返回 kappa 值。

folds = createFolds(mdd.cohort1$edmsemmancomprej, k=10)
str(folds)
mdd.cohort1_train = mdd.cohort1[-folds$Fold01,]
mdd.cohort1_test = mdd.cohort1[folds$Fold01,]
library(caret)
library(C5.0)
library(irr)
set.seed(123)
folds = createFolds(mdd.cohort1$edmsemmancomprej, k=10)

cv_results = lapply(folds, function(x) 
{mdd.cohort1_train = mdd.cohort1[-x, ] 
mdd.cohort1_test = mdd.cohort1[x, ] 
mdd.cohort1_model = C5.0(edmsemmancomprej ~., data = mdd.cohort1_train) 
mdd.cohort1_pred = predict(mdd.cohort1_model, mdd.cohort1_test) 
mdd.cohort1_actual = mdd.cohort1_test$edmsemmancomprej 
kappa = kappa2(data.frame(mdd.cohort1_actual, mdd.cohort1_pred))$value    return(kappa)})

给出以下错误消息:

Error: unexpected symbol in:
"mdd.cohort1_actual = mdd.cohort1_test$edmsemmancomprej
kappa = kappa2(data.frame(mdd.cohort1_actual, mdd.cohort1_pred))$value return"

有谁知道发生了什么吗？提前非常感谢您!

Answer 1

如果没有可重现的示例，这有点困难，但我认为最后一行的返回共享是原因。为了便于阅读，我对您的代码进行了一些重新格式化

library(caret)
library(C5.0)
library(irr)   

folds = createFolds(mdd.cohort1$edmsemmancomprej, k=10)

str(folds)

mdd.cohort1_train = mdd.cohort1[-folds$Fold01,]
mdd.cohort1_test = mdd.cohort1[folds$Fold01,]

set.seed(123)
folds = createFolds(mdd.cohort1$edmsemmancomprej, k=10)

cv_results = lapply(folds, function(x) {
  mdd.cohort1_train = mdd.cohort1[-x, ] 
  mdd.cohort1_test = mdd.cohort1[x, ] 
  mdd.cohort1_model = C5.0(edmsemmancomprej ~., data = mdd.cohort1_train) 
  mdd.cohort1_pred = predict(mdd.cohort1_model, mdd.cohort1_test) 
  mdd.cohort1_actual = mdd.cohort1_test$edmsemmancomprej 
  kappa = kappa2(data.frame(mdd.cohort1_actual, mdd.cohort1_pred))$value    
  return(kappa)
  })