Merge pull request #659 from pfnet/add-validation-to-trial-report

Improve handling of reported values.

optuna/trial.py

@@ -375,6 +375,14 @@ def report(self, value, step=None):
                 Step of the trial (e.g., Epoch of neural network training).
         """
 
+        try:
+            # For convenience, we allow users to report a value that can be cast to `float`.
+            value = float(value)
+        except (TypeError, ValueError):
+            message = 'The `value` argument is of type \'{}\' but supposed to be a float.'.format(
+                type(value).__name__)
+            raise TypeError(message)
+
         self.storage.set_trial_value(self._trial_id, value)
         if step is not None:
             self.storage.set_trial_intermediate_value(self._trial_id, step, value)

tests/test_trial.py

@@ -1,6 +1,7 @@
 import math
 from mock import Mock
 from mock import patch
+import numpy as np
 import pytest
 
 from optuna import distributions
@@ -399,3 +400,28 @@ def objective(trial):
     study.optimize(objective, n_trials=1)
 
     assert study.trials[0].datetime_start == trial_datetime_start[0]
+
+
+def test_trial_report():
+    # type: () -> None
+
+    study = create_study()
+    trial = Trial(study, study._storage.create_new_trial(study.study_id))
+
+    # Report values that can be cast to `float` (OK).
+    trial.report(1.23)
+    trial.report(float('nan'))
+    trial.report('1.23')  # type: ignore
+    trial.report('inf')  # type: ignore
+    trial.report(1)
+    trial.report(np.array([1], dtype=np.float32)[0])
+
+    # Report values that cannot be cast to `float` (Error).
+    with pytest.raises(TypeError):
+        trial.report(None)  # type: ignore
+
+    with pytest.raises(TypeError):
+        trial.report('foo')  # type: ignore
+
+    with pytest.raises(TypeError):
+        trial.report([1, 2, 3])  # type: ignore