Add str method to ActivePhase (#975)

Summary: Pull Request resolved: #975

Differential Revision: D70127457

tests/framework/test_state.py

@@ -53,6 +53,16 @@ def test_active_phase_into_phase(self) -> None:
         predict_phase = ActivePhase.PREDICT
         self.assertEqual(predict_phase.into_phase(), Phase.PREDICT)
 
+    def test_actiive_phase_str(self) -> None:
+        active_phase = ActivePhase.TRAIN
+        self.assertEqual(str(active_phase), "train")
+
+        eval_phase = ActivePhase.EVALUATE
+        self.assertEqual(str(eval_phase), "eval")
+
+        predict_phase = ActivePhase.PREDICT
+        self.assertEqual(str(predict_phase), "predict")
+
     def test_set_evaluate_every_n_steps_or_epochs(self) -> None:
         state = PhaseState(dataloader=[], evaluate_every_n_steps=2)
         state.evaluate_every_n_steps = None

torchtnt/framework/state.py

@@ -74,6 +74,16 @@ def into_phase(self) -> Phase:
         else:
             raise AssertionError("Should match an ActivePhase")
 
+    def __str__(self) -> str:
+        if self == ActivePhase.TRAIN:
+            return "train"
+        elif self == ActivePhase.EVALUATE:
+            return "eval"
+        elif self == ActivePhase.PREDICT:
+            return "predict"
+        else:
+            raise AssertionError("Should match an ActivePhase")
+
 
 class PhaseState(Generic[TData, TStepOutput]):
     """State for each phase (train, eval, predict).