combine-trees.md
In tidypredict: Run Predictions Inside the Database

check_trees_arg() rejects a non-list and an empty list

Code
  check_trees_arg(1:3)
Condition
  Error:
  ! `trees` must be a non-empty list of expressions, not an integer vector.
Code
  check_trees_arg(list())
Condition
  Error:
  ! `trees` must be a non-empty list of expressions, not an empty list.

lightgbm refuses to combine a multiclass fit

Code
  tidypredict_combine_trees(model, tidypredict_trees(model))
Condition
  Error in `tidypredict_combine_trees()`:
  ! Multiclass lightgbm trees cannot be combined into one expression.
  i The fit is one expression per class.
  i Use `tidypredict_fit()` for the whole model instead.

boosted C5.0 refuses to combine its trees

Code
  tidypredict_combine_trees(model, list(1))
Condition
  Error in `tidypredict_combine_trees()`:
  ! Boosted C5.0 trees cannot be recombined arithmetically.
  i Each trial votes with a class label and a confidence, so there are no per-tree numbers to sum or average.
  i Use `tidypredict_fit()` for the whole model instead.