add number of steps in prev epoch to progress (#873)

Summary:
Pull Request resolved: #873

Expose number of steps in prev completed epoch

Reviewed By: diego-urgell

Differential Revision: D60309756

fbshipit-source-id: 8d356f2b4cba4e5e74ad16fa24935864b0f30ea6

Author: galrotem

tests/utils/test_progress.py

@@ -286,3 +286,17 @@ def __iter__(self) -> Iterator[int]:
             ),
             float("inf"),
         )
+
+    def test_num_steps_completed_in_prev_epoch(self) -> None:
+        progress = Progress(
+            num_epochs_completed=2,
+            num_steps_completed=8,
+            num_steps_completed_in_epoch=4,
+        )
+        self.assertEqual(progress.num_steps_completed_in_epoch, 4)
+        self.assertEqual(progress.num_steps_completed_in_prev_epoch, 0)
+
+        progress.increment_epoch()
+
+        self.assertEqual(progress.num_steps_completed_in_epoch, 0)
+        self.assertEqual(progress.num_steps_completed_in_prev_epoch, 4)

torchtnt/utils/progress.py

@@ -22,6 +22,7 @@ def __init__(
         self._num_epochs_completed: int = num_epochs_completed
         self._num_steps_completed: int = num_steps_completed
         self._num_steps_completed_in_epoch: int = num_steps_completed_in_epoch
+        self._num_steps_completed_in_prev_epoch: int = 0
 
     @property
     def num_epochs_completed(self) -> int:
@@ -38,6 +39,11 @@ def num_steps_completed_in_epoch(self) -> int:
         """Number of steps completed thus far in epoch."""
         return self._num_steps_completed_in_epoch
 
+    @property
+    def num_steps_completed_in_prev_epoch(self) -> int:
+        """Number of steps completed in the previous completed epoch."""
+        return self._num_steps_completed_in_prev_epoch
+
     def increment_step(self) -> None:
         """Increment the step counts completed and completed within the epoch."""
         self._num_steps_completed += 1
@@ -46,6 +52,7 @@ def increment_step(self) -> None:
     def increment_epoch(self) -> None:
         """Increment the epochs completed and resets the steps completed within the epoch."""
         self._num_epochs_completed += 1
+        self._num_steps_completed_in_prev_epoch = self._num_steps_completed_in_epoch
         self._num_steps_completed_in_epoch = 0
 
     def state_dict(self) -> Dict[str, Any]: