我想使用Caret模型的“折叠外”预测结果来训练第二阶段模型,该模型包括一些原始的预测变量。我可以按如下方式收集“折叠外”预测结果:
#Load Data
set.seed(1)
library(caret)
library(mlbench)
data(BostonHousing)
#Build Model (see ?train)
rpartFit <- train(medv ~ . + rm:lstat, data = BostonHousing, method="rpart",
trControl=trainControl(method='cv', number=folds,
savePredictions=TRUE))
#Collect out-of-fold predictions
out_of_fold <- rpartFit$pred
bestCP <- rpartFit$bestTune[,'.cp']
out_of_fold <- out_of_fold[out_of_fold$.cp==bestCP,]
这很不错,但它们的顺序是错误的:
> all.equal(out_of_fold$obs, BostonHousing$medv)
[1] "Mean relative difference: 0.4521906"
我知道train
对象返回一个列表,其中包含用于训练每个折叠的索引:> str(rpartFit$control$index)
List of 10
$ Fold01: int [1:457] 1 2 3 4 5 6 7 8 9 10 ...
$ Fold02: int [1:454] 2 3 4 8 10 11 12 13 14 15 ...
$ Fold03: int [1:457] 1 2 3 4 5 6 7 8 9 10 ...
$ Fold04: int [1:455] 1 2 3 5 6 7 8 9 10 11 ...
$ Fold05: int [1:455] 1 2 3 4 5 6 7 8 9 10 ...
$ Fold06: int [1:455] 1 2 3 4 5 6 7 8 9 10 ...
$ Fold07: int [1:457] 1 3 4 5 6 7 8 9 10 13 ...
$ Fold08: int [1:455] 1 2 4 5 6 7 9 11 12 14 ...
$ Fold09: int [1:455] 1 2 3 4 5 6 7 8 9 10 ...
$ Fold10: int [1:454] 1 2 3 4 5 6 7 8 9 10 ...
我该如何利用这些信息,使得我的 out_of_fold
对象中的观测值与原始的 BostonHousing
数据集中的观测值顺序一致?