我的插入符号“ rf”模型中使用了几棵树？

Question

在插入符号“ rf”模型中未指定ntree计数时，我很难找到模型中使用了多少棵树。

这是我用来训练模型的代码：

fitControl <- trainControl(
    method = "cv",                     
    number = 3,                        
    savePredictions = "final",         
    classProbs = T,                   
    summaryFunction = twoClassSummary, 
    sampling = "down")                 

set.seed(3219)
  rf_model_down <- train(Class ~ .,
                         data = train_data,
                         method ='rf',
                         tuneLength = 2,
                         trControl = fitControl,
                         metric = "ROC")

使用print(rf_model_down)函数，我可以看到mtry是什么，但是它不能告诉我们使用的ntree计数。

print(rf_model_down)

# Random Forest 
#
# 10000 samples
#    94 predictor
#     2 classes: 'Fraud', 'notFraud' 
#
# No pre-processing
# Resampling: Cross-Validated (3 fold) 
# Summary of sample sizes: 6667, 6666, 6667 
# Addtional sampling using down-sampling
#
# Resampling results across tuning parameters:
#
#   mtry  ROC        Sens       Spec     
#    2    0.7401603  0.7691257  0.5717070
#   94    0.7449104  0.6814208  0.6641911
#
# ROC was used to select the optimal model using the largest value.
# The final value used for the model was mtry = 94.

在此先感谢我最难找到答案的简单答案...

Answer 1

检查str(rf_model_down)表明我们可以使用

rf_model_down$finalModel$ntree