update.train
を参照してください:
> mod1 <- train(Species ~ ., data = iris, method = "rpart")
> mod1
CART
150 samples
4 predictor
3 classes: 'setosa', 'versicolor', 'virginica'
No pre-processing
Resampling: Bootstrapped (25 reps)
Summary of sample sizes: 150, 150, 150, 150, 150, 150, ...
Resampling results across tuning parameters:
cp Accuracy Kappa
0.00 0.9434796 0.9145259
0.44 0.7609620 0.6544837
0.50 0.4731651 0.2350673
Accuracy was used to select the optimal model using the largest value.
The final value used for the model was cp = 0.
> update(mod1, param = list(cp = .44))
CART
150 samples
4 predictor
3 classes: 'setosa', 'versicolor', 'virginica'
No pre-processing
Resampling: Bootstrapped (25 reps)
Summary of sample sizes: 150, 150, 150, 150, 150, 150, ...
Resampling results across tuning parameters:
cp Accuracy Kappa
0.00 0.9434796 0.9145259
0.44 0.7609620 0.6544837
0.50 0.4731651 0.2350673
The tuning parameter was set manually.
The final value used for the model was cp = 0.44.