r - 与游侠的重要性不同

Question

我使用 caret + ranger 训练了一个随机森林。

fit <- train(
    y ~ x1 + x2
    ,data = total_set
    ,method = "ranger"
    ,trControl = trainControl(method="cv", number = 5, allowParallel = TRUE, verbose = TRUE)
    ,tuneGrid = expand.grid(mtry = c(4,5,6))
    ,importance = 'impurity'
)

现在我想看看变量的重要性。然而，这些都不起作用:

> importance(fit)
Error in UseMethod("importance") : no applicable method for 'importance' applied to an object of class "c('train', 'train.formula')"
> fit$variable.importance
NULL
> fit$importance
NULL

> fit
Random Forest 

217380 samples
    32 predictors

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 173904, 173904, 173904, 173904, 173904 
Resampling results across tuning parameters:

  mtry  RMSE        Rsquared 
  4     0.03640464  0.5378731
  5     0.03645528  0.5366478
  6     0.03651451  0.5352838

RMSE was used to select the optimal model using  the smallest value.
The final value used for the model was mtry = 4. 

知道我是否能够得到它以及如何得到它吗？

谢谢。

Answer 1

varImp(fit) 将为您获取它。

为了弄清楚这一点，我查看了 names(fit)，这导致我找到 names(fit$modelInfo) - 然后你会看到 varImp 作为选项之一。