Add support for conditionals in TrialToArrayConverter.

vizier/_src/pyvizier/shared/parameter_config.py

@@ -17,7 +17,7 @@
 """ParameterConfig wraps ParameterConfig and ParameterSpec protos."""
 
 import collections
-from typing import Collection, Set as AbstractSet, Sized
+from typing import Iterable, Set as AbstractSet, Sized
 import copy
 import enum
 import json
@@ -410,7 +410,7 @@ def child_parameter_configs(self) -> List['ParameterConfig']:
 
   def subspaces(
       self,
-  ) -> Collection[Tuple[ParameterValueTypes, 'SearchSpace']]:
+  ) -> Iterable[Tuple[ParameterValueTypes, 'SearchSpace']]:
     return self._children.items()
 
   # TODO: TO BE DEPRECATED.
@@ -724,24 +724,26 @@ def subspace(self, value: ParameterValueTypes) -> 'SearchSpace':
     return self._children[value]
 
 
-ParameterConfigOrConfigs = Union[ParameterConfig, Collection[ParameterConfig]]
-
-
 @attr.define(init=False)
-class ParameterConfigSelector(Sized):
+class ParameterConfigSelector(Iterable[ParameterConfig], Sized):
   """Holds a reference to ParameterConfigs."""
 
   # Selected configs.
-  _selected: tuple[ParameterConfig] = attr.field(init=True)
+  _selected: tuple[ParameterConfig] = attr.field(init=True, converter=tuple)
+
+  def __iter__(self) -> Iterator[ParameterConfig]:
+    return iter(self._selected)
 
   def __len__(self) -> int:
     return len(self._selected)
 
-  def __init__(self, selected: ParameterConfigOrConfigs):
-    if isinstance(selected, Collection):
-      self.__attrs_init__(tuple(selected))
-    else:
+  def __init__(
+      self, selected: Union[ParameterConfig, Iterable[ParameterConfig]], /
+  ):
+    if isinstance(selected, ParameterConfig):
       self.__attrs_init__(tuple([selected]))
+    else:
+      self.__attrs_init__(tuple(selected))
 
   def select_values(
       self, values: MonotypeParameterSequence
@@ -762,13 +764,29 @@ def select_values(
         spaces.append(config.subspace(value))
     return SearchSpaceSelector(spaces)
 
+  def merge(self) -> 'ParameterConfigSelector':
+    """Merge by taking the union of the parameter configs with the same name.
+
+    Returns:
+      The returned ParameterConfigSelector does not contain parameters with
+      duplicate names. Their feasible set (either as a range or discrete set) is
+      the union of all feasible sets under the same parameter name.
+    """
+    merged_configs = {}
+    for parameter_config in self:
+      name = parameter_config.name  # Alias
+      existing_config = merged_configs.setdefault(name, parameter_config)
+      merged_configs[name] = ParameterConfig.merge(
+          existing_config, parameter_config
+      )
+    return ParameterConfigSelector(merged_configs.values())
+
 
 class InvalidParameterError(ValueError):
   """Error thrown when parameter values are invalid."""
 
 
 ################### Main Classes ###################
-SearchSpaceOrSpaces = Union['SearchSpace', Collection['SearchSpace']]
 
 
 @attr.define(init=False)
@@ -783,11 +801,13 @@ class SearchSpaceSelector:
   def __len__(self) -> int:
     return len(self._selected)
 
-  def __init__(self, selected: SearchSpaceOrSpaces):
-    if isinstance(selected, Collection):
-      self.__attrs_init__(tuple(selected))
-    else:
+  def __init__(
+      self, selected: Union['SearchSpace', Iterable['SearchSpace']], /
+  ):
+    if isinstance(selected, SearchSpace):
       self.__attrs_init__(tuple([selected]))
+    else:
+      self.__attrs_init__(tuple(selected))
 
   def add_float_param(
       self,
@@ -1239,7 +1259,7 @@ def parse_multi_dimensional_parameter_name(
 
   # TODO: Add def extend(space: SearchSpace)
   def _add_parameters(
-      self, parameters: List[ParameterConfig]
+      self, parameters: Iterable[ParameterConfig]
   ) -> ParameterConfigSelector:
     """Adds deepcopy of the ParameterConfigs.
 
@@ -1249,6 +1269,7 @@ def _add_parameters(
     Returns:
       A list of SearchSpaceSelectors, one for each parameters added.
     """
+    parameters = list(parameters)
     logging.info(
         'Adding child parameters %s to %s subspaces ',
         set(p.name for p in parameters),
@@ -1262,6 +1283,15 @@ def _add_parameters(
 
     return ParameterConfigSelector(added)
 
+  def select_all(self) -> ParameterConfigSelector:
+    """Select all parameters at all levels."""
+    all_parameter_configs = []
+    for space in self._selected:
+      for top_level_config in space.parameters:
+        all_parameter_configs.extend(list(top_level_config.traverse()))
+
+    return ParameterConfigSelector(all_parameter_configs)
+
 
 @attr.define(frozen=False, init=True, slots=True, kw_only=True)
 class SearchSpace:

vizier/_src/pyvizier/shared/parameter_config_test.py

@@ -18,8 +18,10 @@
 
 from typing import Any
 
+from absl import logging
 from vizier._src.pyvizier.shared import parameter_config as pc
 from vizier._src.pyvizier.shared import trial
+from vizier.testing import test_studies
 
 from absl.testing import absltest
 from absl.testing import parameterized
@@ -557,6 +559,24 @@ def testValidateCategoricalInput(self):
       root.add_categorical_param('categorical', ['3.2', '2', 5])
 
 
+class FlattenAndMergeTest(absltest.TestCase):
+
+  def testFlattenAndMerge(self):
+    space = test_studies.conditional_automl_space()
+    parameters = space.root.select_all().merge()
+    logging.info('Merged: %s', parameters)
+    self.assertCountEqual(
+        [p.name for p in parameters],
+        [
+            'model_type',
+            'learning_rate',
+            'optimizer_type',
+            'use_special_logic',
+            'special_logic_parameter',
+        ],
+    )
+
+
 class SearchSpaceContainsTest(absltest.TestCase):
 
   def _space(self):

vizier/pyvizier/converters/core.py

@@ -20,7 +20,6 @@
 import copy
 import dataclasses
 import enum
-import itertools
 from typing import Any, Callable, Collection, Dict, Iterator, List, Mapping, Optional, Sequence, Tuple, Type, Union
 
 from absl import logging
@@ -1147,29 +1146,17 @@ def from_study_configs(
     Returns:
       `DefaultTrialConverter`.
     """
-    # Cache ParameterConfigs.
-    # Traverse through all parameter configs and merge the same-named ones.
-    parameter_configs: Dict[str, pyvizier.ParameterConfig] = dict()
-    for study_config in study_configs:
-      all_parameter_configs = itertools.chain.from_iterable(
-          [
-              top_level_config.traverse()
-              for top_level_config in study_config.search_space.parameters
-          ]
-      )
-      for parameter_config in all_parameter_configs:
-        name = parameter_config.name  # Alias
-        existing_config = parameter_configs.get(name, None)
-        if existing_config is None:
-          parameter_configs[name] = parameter_config
-        else:
-          parameter_configs[name] = pyvizier.ParameterConfig.merge(
-              existing_config, parameter_config
-          )
+    # Merge parameter configs by name.
+    merged_configs = list(
+        pyvizier.SearchSpaceSelector([sc.search_space for sc in study_configs])
+        .select_all()
+        .merge()
+    )
 
-    parameter_converters = []
-    for pc in parameter_configs.values():
-      parameter_converters.append(DefaultModelInputConverter(pc))
+    merged_configs = {pc.name: pc for pc in merged_configs}
+    parameter_converters = [
+        DefaultModelInputConverter(pc) for pc in merged_configs.values()
+    ]
 
     # Append study id feature if configured to do so.
     if use_study_id_feature:
@@ -1188,17 +1175,17 @@ def from_study_configs(
             'had study id configured.'
         )
         use_study_id_feature = False
-      elif STUDY_ID_FIELD in parameter_configs:
+      elif STUDY_ID_FIELD in merged_configs:
         raise ValueError(
             'Dataset name conflicts with a ParameterConfig '
-            'that already exists: {}'.format(parameter_configs[STUDY_ID_FIELD])
+            'that already exists: {}'.format(merged_configs[STUDY_ID_FIELD])
         )
 
       # Create new parameter config.
       parameter_config = pyvizier.ParameterConfig.factory(
           STUDY_ID_FIELD, feasible_values=list(study_ids)
       )
-      parameter_configs[STUDY_ID_FIELD] = parameter_config
+      merged_configs[STUDY_ID_FIELD] = parameter_config
       logging.info('Created a new ParameterConfig %s', parameter_config)
 
       # Create converter.
@@ -1309,7 +1296,10 @@ def create_output_converter(metric):
 
     sc = study_config  # alias, to keep pylint quiet in the next line.
     converter = DefaultTrialConverter(
-        [create_input_converter(p) for p in sc.search_space.parameters],
+        [
+            create_input_converter(p)
+            for p in sc.search_space.root.select_all().merge()
+        ],
         [create_output_converter(m) for m in sc.metric_information],
     )
     return cls(converter)

vizier/pyvizier/converters/core_test.py

@@ -31,6 +31,22 @@
 Trial = pyvizier.Trial
 
 
+class TrialToArrayConverterConditionalSpaceTest(parameterized.TestCase):
+
+  def test_automl_study(self):
+    space = test_studies.conditional_automl_space()
+    converter = core.TrialToArrayConverter.from_study_config(
+        pyvizier.ProblemStatement(search_space=space)
+    )
+    features = converter.to_features([pyvizier.Trial()])
+    np.testing.assert_equal(
+        features,
+        np.array(
+            [[0.0, 0.0, 1.0, np.nan, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, np.nan]]
+        ),
+    )
+
+
 class TrialToArrayConverterTest(parameterized.TestCase):
   """Test TrialToArrayConverter class."""