[tune] Improve missing search dependency info (#23691)

Replaces FLAML searchers with a dummy class that throws an informative error on init if FLAML is not installed, removes ConfigSpace import in BOHB example code, adds a note to examples using external dependencies.

python/ray/tune/examples/ax_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of AxSearch with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the Ax library to be installed (`pip install ax-platform sqlalchemy`).
 """
 import numpy as np
 import time

python/ray/tune/examples/bayesopt_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of BayesOpt with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the BayesOpt library to be installed (`pip install bayesian-optimization`).
 """
 import time
 

python/ray/tune/examples/blendsearch_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of BlendSearch with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the FLAML library to be installed (`pip install flaml`).
 """
 import time
 

python/ray/tune/examples/bohb_example.py

@@ -1,5 +1,11 @@
 #!/usr/bin/env python
 
+"""This example demonstrates the usage of BOHB with Ray Tune.
+
+Requires the HpBandSter and ConfigSpace libraries to be installed
+(`pip install hpbandster ConfigSpace`).
+"""
+
 import argparse
 import json
 import time
@@ -45,8 +51,6 @@ class MyTrainableClass(Trainable):
 
 
 if __name__ == "__main__":
-    import ConfigSpace as CS  # noqa: F401
-
     parser = argparse.ArgumentParser()
     parser.add_argument(
         "--server-address",
@@ -70,6 +74,7 @@ if __name__ == "__main__":
     }
 
     # Optional: Pass the parameter space yourself
+    # import ConfigSpace as CS
     # config_space = CS.ConfigurationSpace()
     # config_space.add_hyperparameter(
     #     CS.UniformFloatHyperparameter("width", lower=0, upper=20))

python/ray/tune/examples/cfo_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of CFO with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the FLAML library to be installed (`pip install flaml`).
 """
 import time
 

python/ray/tune/examples/dragonfly_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of Dragonfly with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the Dragonfly library to be installed (`pip install dragonfly-opt`).
 """
 from __future__ import absolute_import
 from __future__ import division

python/ray/tune/examples/hebo_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of HEBO with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the HEBO library to be installed (`pip install 'HEBO>=0.2.0'`).
 """
 import time
 

python/ray/tune/examples/hyperopt_conditional_search_space_example.py

@@ -2,6 +2,8 @@
 
 It also checks that it is usable with a separate scheduler.
 
+Requires the HyperOpt library to be installed (`pip install hyperopt`).
+
 For an example of using a Tune search space, see
 :doc:`/tune/examples/hyperopt_example`.
 """

python/ray/tune/examples/nevergrad_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of Nevergrad with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the Nevergrad library to be installed (`pip install nevergrad`).
 """
 import time
 

python/ray/tune/examples/optuna_define_by_run_example.py

@@ -2,6 +2,8 @@
 
 It also checks that it is usable with a separate scheduler.
 
+Requires the Optuna library to be installed (`pip install optuna`).
+
 For an example of using a Tune search space, see
 :doc:`/tune/examples/optuna_example`.
 """

python/ray/tune/examples/optuna_example.py

@@ -2,6 +2,8 @@
 
 It also checks that it is usable with a separate scheduler.
 
+Requires the Optuna library to be installed (`pip install optuna`).
+
 For an example of using an Optuna define-by-run function, see
 :doc:`/tune/examples/optuna_define_by_run_example`.
 """

python/ray/tune/examples/optuna_multiobjective_example.py

@@ -3,6 +3,8 @@ multi-objective optimization.
 
 Please note that schedulers may not work correctly with multi-objective
 optimization.
+
+Requires the Optuna library to be installed (`pip install optuna`).
 """
 import time
 

python/ray/tune/examples/sigopt_example.py

@@ -1,6 +1,8 @@
 """This example demonstrates the usage of SigOpt with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the SigOpt library to be installed (`pip install sigopt`).
 """
 import sys
 import time

python/ray/tune/examples/sigopt_multi_objective_example.py

@@ -1,4 +1,8 @@
-"""Example using Sigopt's multi-objective functionality."""
+"""
+Example using Sigopt's multi-objective functionality.
+
+Requires the SigOpt library to be installed (`pip install sigopt`).
+"""
 import sys
 import time
 

python/ray/tune/examples/sigopt_prior_beliefs_example.py

@@ -1,4 +1,8 @@
-""""Example using Sigopt's support for prior beliefs."""
+""""
+Example using Sigopt's support for prior beliefs.
+
+Requires the SigOpt library to be installed (`pip install sigopt`).
+"""
 import sys
 
 import numpy as np

python/ray/tune/examples/skopt_example.py

@@ -1,6 +1,8 @@
-"""This example demonstrates the usage of Skopt with Ray Tune.
+"""This example demonstrates the usage of SkOpt with Ray Tune.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the SkOpt library to be installed (`pip install scikit-optimize`).
 """
 import time
 

python/ray/tune/examples/zoopt_example.py

@@ -1,13 +1,14 @@
 """This example demonstrates the usage of ZOOptSearch.
 
 It also checks that it is usable with a separate scheduler.
+
+Requires the ZOOpt library to be installed (`pip install zoopt`).
 """
 import time
 
 from ray import tune
 from ray.tune.suggest.zoopt import ZOOptSearch
 from ray.tune.schedulers import AsyncHyperBandScheduler
-from zoopt import ValueType  # noqa: F401
 
 
 def evaluation_fn(step, width, height):
@@ -50,6 +51,7 @@ if __name__ == "__main__":
     num_samples = 10 if args.smoke_test else 1000
 
     # Optional: Pass the parameter space yourself
+    # from zoopt import ValueType
     # space = {
     #     # for continuous dimensions: (continuous, search_range, precision)
     #     "height": (ValueType.CONTINUOUS, [-10, 10], 1e-2),

python/ray/tune/suggest/flaml.py

@@ -1,4 +1,13 @@
 try:
     from flaml import BlendSearch, CFO
 except ImportError:
-    BlendSearch = CFO = None
+
+    class _DummyErrorRaiser:
+        def __init__(self, *args, **kwargs) -> None:
+            raise ImportError(
+                "FLAML must be installed! "
+                "You can install FLAML with the command: "
+                "`pip install flaml`."
+            )
+
+    BlendSearch = CFO = _DummyErrorRaiser

python/ray/tune/suggest/hebo.py

@@ -139,7 +139,7 @@ class HEBOSearch(Searcher):
     ):
         assert hebo is not None, (
             "HEBO must be installed! You can install HEBO with"
-            " the command: `pip install 'HEBO>=0.2.0'."
+            " the command: `pip install 'HEBO>=0.2.0'`."
             "This error may also be caused if HEBO"
             " dependencies have bad versions. Try updating HEBO"
             " first."

python/ray/tune/tests/test_soft_imports.py

@@ -15,7 +15,7 @@ class TestSoftImports(unittest.TestCase):
 
             # ensure that the dependencies aren't actually installed
             if searcher and name not in ("variant_generator", "random"):
-                with self.assertRaises(AssertionError):
+                with self.assertRaises((AssertionError, ImportError)):
                     searcher()