Revert "Adding max_iters as an optional arg in Engine run (#1381)"

This reverts commit 307ac11.

ignite/engine/engine.py

@@ -1,6 +1,5 @@
 import functools
 import logging
-import math
 import time
 import warnings
 import weakref
@@ -680,7 +679,7 @@ def load_state_dict(self, state_dict: Mapping) -> None:
         `seed`. If `engine.state_dict_user_keys` contains keys, they should be also present in the state dictionary.
         Iteration and epoch values are 0-based: the first iteration or epoch is zero.
 
-        This method does not remove any custom attributes added by user.
+        This method does not remove any custom attributs added by user.
 
         Args:
             state_dict: a dict with parameters
@@ -725,14 +724,7 @@ def load_state_dict(self, state_dict: Mapping) -> None:
 
     @staticmethod
     def _is_done(state: State) -> bool:
-        is_done_iters = state.max_iters is not None and state.iteration >= state.max_iters
-        is_done_count = (
-            state.epoch_length is not None
-            and state.max_epochs is not None
-            and state.iteration >= state.epoch_length * state.max_epochs
-        )
-        is_done_epochs = state.max_epochs is not None and state.epoch >= state.max_epochs
-        return is_done_iters or is_done_count or is_done_epochs
+        return state.iteration == state.epoch_length * state.max_epochs  # type: ignore[operator]
 
     def set_data(self, data: Union[Iterable, DataLoader]) -> None:
         """Method to set data. After calling the method the next batch passed to `processing_function` is
@@ -774,15 +766,14 @@ def run(
         self,
         data: Optional[Iterable] = None,
         max_epochs: Optional[int] = None,
-        max_iters: Optional[int] = None,
         epoch_length: Optional[int] = None,
         seed: Optional[int] = None,
     ) -> State:
         """Runs the ``process_function`` over the passed data.
 
         Engine has a state and the following logic is applied in this function:
 
-        - At the first call, new state is defined by `max_epochs`, `max_iters`, `epoch_length`, `seed`, if provided.
+        - At the first call, new state is defined by `max_epochs`, `epoch_length`, `seed`, if provided.
           A timer for total and per-epoch time is initialized when Events.STARTED is handled.
         - If state is already defined such that there are iterations to run until `max_epochs` and no input arguments
           provided, state is kept and used in the function.
@@ -800,8 +791,6 @@ def run(
                 `len(data)`. If `data` is an iterator and `epoch_length` is not set, then it will be automatically
                 determined as the iteration on which data iterator raises `StopIteration`.
                 This argument should not change if run is resuming from a state.
-            max_iters: Number of iterations to run for.
-                `max_iters` and `max_epochs` are mutually exclusive; only one of the two arguments should be provided.
             seed: Deprecated argument. Please, use `torch.manual_seed` or :meth:`~ignite.utils.manual_seed`.
 
         Returns:
@@ -860,6 +849,8 @@ def switch_batch(engine):
 
         if self.state.max_epochs is None or (self._is_done(self.state) and self._internal_run_generator is None):
             # Create new state
+            if max_epochs is None:
+                max_epochs = 1
             if epoch_length is None:
                 if data is None:
                     raise ValueError("epoch_length should be provided if data is None")
@@ -868,22 +859,9 @@ def switch_batch(engine):
                 if epoch_length is not None and epoch_length < 1:
                     raise ValueError("Input data has zero size. Please provide non-empty data")
 
-            if max_iters is None:
-                if max_epochs is None:
-                    max_epochs = 1
-            else:
-                if max_epochs is not None:
-                    raise ValueError(
-                        "Arguments max_iters and max_epochs are mutually exclusive."
-                        "Please provide only max_epochs or max_iters."
-                    )
-                if epoch_length is not None:
-                    max_epochs = math.ceil(max_iters / epoch_length)
-
             self.state.iteration = 0
             self.state.epoch = 0
             self.state.max_epochs = max_epochs
-            self.state.max_iters = max_iters
             self.state.epoch_length = epoch_length
             # Reset generator if previously used
             self._internal_run_generator = None
@@ -978,6 +956,7 @@ def _internal_run_as_gen(self) -> Generator:
                     self.state.times[Events.EPOCH_COMPLETED.name] = epoch_time_taken
 
                     handlers_start_time = time.time()
+
                     self._fire_event(Events.EPOCH_COMPLETED)
                     epoch_time_taken += time.time() - handlers_start_time
                     # update time wrt handlers
@@ -1056,8 +1035,6 @@ def _run_once_on_dataset_as_gen(self) -> Generator[State, None, float]:
                     if self.state.epoch_length is None:
                         # Define epoch length and stop the epoch
                         self.state.epoch_length = iter_counter
-                        if self.state.max_iters is not None:
-                            self.state.max_epochs = math.ceil(self.state.max_iters / self.state.epoch_length)
                         break
 
                     # Should exit while loop if we can not iterate

ignite/engine/events.py

@@ -379,7 +379,6 @@ class State:
         state.dataloader        # data passed to engine
         state.epoch_length      # optional length of an epoch
         state.max_epochs        # number of epochs to run
-        state.max_iters         # number of iterations to run
         state.batch             # batch passed to `process_function`
         state.output            # output of `process_function` after a single iteration
         state.metrics           # dictionary with defined metrics if any
@@ -406,7 +405,6 @@ def __init__(self, **kwargs: Any) -> None:
         self.epoch = 0
         self.epoch_length = None  # type: Optional[int]
         self.max_epochs = None  # type: Optional[int]
-        self.max_iters = None  # type: Optional[int]
         self.output = None  # type: Optional[int]
         self.batch = None  # type: Optional[int]
         self.metrics = {}  # type: Dict[str, Any]