[tmva] Warn when using RBDT and xgboost

Representing the current situation at #15197

bindings/pyroot/pythonizations/python/ROOT/_pythonization/_tmva/_rbdt.py

@@ -35,11 +35,24 @@ def Compute(self, x):
     # As fall-through we go to the original compute function and use the error-handling from cppyy
     return self._OriginalCompute(x)
 
+def RBDTInit(self, *args, **kwargs):
+    import warnings
+    warnings.warn(
+        ("Usage of xgboost models through RBDT is known to be limited and may "
+         "lead to unexpected behaviour. Proceed with caution if the input model "
+         "was obtained via `SaveXGBoost`. See https://github.com/root-project/root/issues/15197 "
+         "for more details."), UserWarning, stacklevel=2)
+
+    return self._original_init(*args, **kwargs)
+
 
 @pythonization("RBDT", ns="TMVA::Experimental", is_prefix=True)
 def pythonize_rbdt(klass):
     # Parameters:
     # klass: class to be pythonized
 
+    klass._original_init = klass.__init__
+    klass.__init__ = RBDTInit
+
     klass._OriginalCompute = klass.Compute
     klass.Compute = Compute

bindings/pyroot/pythonizations/python/ROOT/_pythonization/_tmva/_tree_inference.py

@@ -12,7 +12,12 @@
 import cppyy
 
 
-def SaveXGBoost(self, xgb_model, key_name, output_path, num_inputs=None, tmp_path="/tmp", threshold_dtype="float"):
+def SaveXGBoost(self, xgb_model, key_name, output_path, num_inputs, tmp_path="/tmp", threshold_dtype="float"):
+    import warnings
+    warnings.warn(
+        ("Usage of xgboost models through RBDT is known to be limited and may "
+         "lead to unexpected behaviour. See https://github.com/root-project/root/issues/15197 "
+         "for more details."), UserWarning, stacklevel=2)
     # Extract objective
     objective_map = {
         "multi:softprob": "softmax",  # Naming the objective softmax is more common today

tmva/tmva/test/CMakeLists.txt

@@ -34,8 +34,9 @@ if(dataframe)
 endif()
 
 # Disabled because RBDT doesn't support the imbalanced tree structure of
-# XGBoost models.
-# if(dataframe AND NOT pyroot_legacy)
+# XGBoost models. See https://github.com/root-project/root/issues/15197
+# TODO: Re-enable once fixed
+# if(dataframe)
 #   find_python_module(xgboost QUIET)
 #   if (PY_XGBOOST_FOUND)
 #     ROOT_ADD_PYUNITTEST(rbdt_xgboost rbdt_xgboost.py)

tutorials/CMakeLists.txt

@@ -297,6 +297,10 @@ set(gui_veto fit/fitpanel_playback.C
 if (NOT ROOT_tmva_FOUND)
   list(APPEND tmva_veto tmva/*.C tmva/*.py tmva/envelope/*.C tmva/keras/*.C tmva/keras/*.py tmva/pytorch/*.py )
 else()
+  # RBDT with xgboost is currently broken, disable all tutorials that use it
+  # See https://github.com/root-project/root/issues/15197
+  # TODO: Re-enable once fixed
+  list(APPEND tmva_veto tmva/tmva10[0-2]_*.py)
   #---These do not need to run for TMVA
   list(APPEND tmva_veto tmva/createData.C)
   if(MSVC AND NOT win_broken_tests)