[CLI] Shorthand notation to instantiate optimizers and lr schedulers [2/3]

CHANGELOG.md

@@ -53,6 +53,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
   * Added `LightningCLI(run=False|True)` to choose whether to run a `Trainer` subcommand ([#8751](https://github.com/PyTorchLightning/pytorch-lightning/pull/8751))
   * Added support to call any trainer function from the `LightningCLI` via subcommands ([#7508](https://github.com/PyTorchLightning/pytorch-lightning/pull/7508))
   * Allow easy trainer re-instantiation ([#7508](https://github.com/PyTorchLightning/pytorch-lightning/pull/9241))
+  * Automatically register all optimizers and learning rate schedulers ([#9565](https://github.com/PyTorchLightning/pytorch-lightning/pull/9565))
+  * Allow registering custom optimizers and learning rate schedulers without subclassing the CLI ([#9565](https://github.com/PyTorchLightning/pytorch-lightning/pull/9565))
+  * Support shorthand notation to instantiate optimizers and learning rate schedulers ([#9565](https://github.com/PyTorchLightning/pytorch-lightning/pull/9565))
 
 
 - Fault-tolerant training:

docs/source/common/lightning_cli.rst

@@ -665,69 +665,135 @@ Optimizers and learning rate schedulers
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Optimizers and learning rate schedulers can also be made configurable. The most common case is when a model only has a
-single optimizer and optionally a single learning rate scheduler. In this case the model's
-:class:`~pytorch_lightning.core.lightning.LightningModule` could be left without implementing the
-:code:`configure_optimizers` method since it is normally always the same and just adds boilerplate. The following code
-snippet shows how to implement it:
+single optimizer and optionally a single learning rate scheduler. In this case, the model's
+:meth:`~pytorch_lightning.core.lightning.LightningModule.configure_optimizers` could be left unimplemented since it is
+normally always the same and just adds boilerplate.
 
-.. testcode::
-
-    import torch
-
-
-    class MyLightningCLI(LightningCLI):
-        def add_arguments_to_parser(self, parser):
-            parser.add_optimizer_args(torch.optim.Adam)
-            parser.add_lr_scheduler_args(torch.optim.lr_scheduler.ExponentialLR)
+The CLI works out-of-the-box with PyTorch's built-in optimizers and learning rate schedulers when
+at most one of each is used.
+Only the optimizer or scheduler name needs to be passed, optionally with its ``__init__`` arguments:
 
+.. code-block:: bash
 
-    cli = MyLightningCLI(MyModel)
+    $ python trainer.py fit --optimizer=Adam --optimizer.lr=0.01 --lr_scheduler=ExponentialLR --lr_scheduler.gamma=0.1
 
-With this the :code:`configure_optimizers` method is automatically implemented and in the config the :code:`optimizer`
-and :code:`lr_scheduler` groups would accept all of the options for the given classes, in this example :code:`Adam` and
-:code:`ExponentialLR`. Therefore, the config file would be structured like:
+A corresponding example of the config file would be:
 
 .. code-block:: yaml
 
     optimizer:
-      lr: 0.01
+      class_path: torch.optim.Adam
+      init_args:
+        lr: 0.01
     lr_scheduler:
-      gamma: 0.2
+      class_path: torch.optim.lr_scheduler.ExponentialLR
+      init_args:
+        gamma: 0.1
     model:
       ...
     trainer:
       ...
 
-And any of these arguments could be passed directly through command line. For example:
+.. note::
+
+    This short-hand notation is only supported in the shell and not inside a configuration file. The configuration file
+    generated by calling the previous command with ``--print_config`` will have the ``class_path`` notation.
+
+Furthermore, you can register your own optimizers and/or learning rate schedulers as follows:
+
+.. code-block:: python
+
+    from pytorch_lightning.utilities.cli import OPTIMIZER_REGISTRY, LR_SCHEDULER_REGISTRY
+
+
+    @OPTIMIZER_REGISTRY
+    class CustomAdam(torch.optim.Adam):
+        ...
+
+
+    @LR_SCHEDULER_REGISTRY
+    class CustomCosineAnnealingLR(torch.optim.lr_scheduler.CosineAnnealingLR):
+        ...
+
+
+    # register all `Optimizer` subclasses from the `torch.optim` package
+    # This is done automatically!
+    OPTIMIZER_REGISTRY.register_classes(torch.optim, Optimizer)
+
+    cli = LightningCLI(...)
 
 .. code-block:: bash
 
-    $ python trainer.py fit --optimizer.lr=0.01 --lr_scheduler.gamma=0.2
+    $ python trainer.py fit --optimizer=CustomAdam --optimizer.lr=0.01 --lr_scheduler=CustomCosineAnnealingLR
+
+If you need to customize the key names or link arguments together, you can choose from all available optimizers and
+learning rate schedulers by accessing the registries.
+
+.. code-block::
+
+    class MyLightningCLI(LightningCLI):
+        def add_arguments_to_parser(self, parser):
+            parser.add_optimizer_args(
+                OPTIMIZER_REGISTRY.classes,
+                nested_key="gen_optimizer",
+                link_to="model.optimizer1_init"
+            )
+            parser.add_optimizer_args(
+                OPTIMIZER_REGISTRY.classes,
+                nested_key="gen_discriminator",
+                link_to="model.optimizer2_init"
+            )
+
+.. code-block:: bash
+
+    $ python trainer.py fit \
+        --gen_optimizer=Adam \
+        --gen_optimizer.lr=0.01 \
+        --gen_discriminator=AdamW \
+        --gen_discriminator.lr=0.0001
+
+You can also use pass the class path directly, for example, if the optimizer hasn't been registered to the
+``OPTIMIZER_REGISTRY``:
+
+.. code-block:: bash
+
+    $ python trainer.py fit \
+        --gen_optimizer.class_path=torch.optim.Adam \
+        --gen_optimizer.init_args.lr=0.01 \
+        --gen_discriminator.class_path=torch.optim.AdamW \
+        --gen_discriminator.init_args.lr=0.0001
 
-There is also the possibility of selecting among multiple classes by giving them as a tuple. For example:
+If you will not be changing the class, you can manually add the arguments for specific optimizers and/or
+learning rate schedulers by subclassing the CLI. This has the advantage of providing the proper help message for those
+classes. The following code snippet shows how to implement it:
 
 .. testcode::
 
     class MyLightningCLI(LightningCLI):
         def add_arguments_to_parser(self, parser):
-            parser.add_optimizer_args((torch.optim.SGD, torch.optim.Adam))
+            parser.add_optimizer_args(torch.optim.Adam)
+            parser.add_lr_scheduler_args(torch.optim.lr_scheduler.ExponentialLR)
 
-In this case in the config the :code:`optimizer` group instead of having directly init settings, it should specify
-:code:`class_path` and optionally :code:`init_args`. Sub-classes of the classes in the tuple would also be accepted.
-A corresponding example of the config file would be:
+With this, in the config the :code:`optimizer` and :code:`lr_scheduler` groups would accept all of the options for the
+given classes, in this example :code:`Adam` and :code:`ExponentialLR`.
+Therefore, the config file would be structured like:
 
 .. code-block:: yaml
 
     optimizer:
-      class_path: torch.optim.Adam
-      init_args:
-        lr: 0.01
+      lr: 0.01
+    lr_scheduler:
+      gamma: 0.2
+    model:
+      ...
+    trainer:
+      ...
 
-And the same through command line:
+Where the arguments can be passed directly through command line without specifying the class. For example:
 
 .. code-block:: bash
 
-    $ python trainer.py fit --optimizer.class_path=torch.optim.Adam --optimizer.init_args.lr=0.01
+    $ python trainer.py fit --optimizer.lr=0.01 --lr_scheduler.gamma=0.2
 
 The automatic implementation of :code:`configure_optimizers` can be disabled by linking the configuration group. An
 example can be :code:`ReduceLROnPlateau` which requires to specify a monitor. This would be:
@@ -763,12 +829,11 @@ example can be :code:`ReduceLROnPlateau` which requires to specify a monitor. Th
 
     cli = MyLightningCLI(MyModel)
 
-For both possibilities of using :meth:`pytorch_lightning.utilities.cli.LightningArgumentParser.add_optimizer_args` with
-a single class or a tuple of classes, the value given to :code:`optimizer_init` will always be a dictionary including
-:code:`class_path` and :code:`init_args` entries. The function
-:func:`~pytorch_lightning.utilities.cli.instantiate_class` takes care of importing the class defined in
-:code:`class_path` and instantiating it using some positional arguments, in this case :code:`self.parameters()`, and the
-:code:`init_args`. Any number of optimizers and learning rate schedulers can be added when using :code:`link_to`.
+The value given to :code:`optimizer_init` will always be a dictionary including :code:`class_path` and
+:code:`init_args` entries. The function :func:`~pytorch_lightning.utilities.cli.instantiate_class`
+takes care of importing the class defined in :code:`class_path` and instantiating it using some positional arguments,
+in this case :code:`self.parameters()`, and the :code:`init_args`.
+Any number of optimizers and learning rate schedulers can be added when using :code:`link_to`.
 
 
 Notes related to reproducibility

pytorch_lightning/utilities/cli.py

@@ -11,11 +11,15 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import inspect
 import os
+import sys
 from argparse import Namespace
-from types import MethodType
+from types import MethodType, ModuleType
 from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Type, Union
+from unittest import mock
 
+import torch
 from torch.optim import Optimizer
 
 from pytorch_lightning import Callback, LightningDataModule, LightningModule, seed_everything, Trainer
@@ -35,9 +39,57 @@
     ArgumentParser = object
 
 
+class _Registry(dict):
+    def __call__(self, cls: Type, key: Optional[str] = None, override: bool = False) -> None:
+        """Registers a class mapped to a name.
+
+        Args:
+            cls: the class to be mapped.
+            key: the name that identifies the provided class.
+            override: Whether to override an existing key.
+        """
+        if key is None:
+            key = cls.__name__
+        elif not isinstance(key, str):
+            raise TypeError(f"`key` must be a str, found {key}")
+
+        if key in self and not override:
+            raise MisconfigurationException(f"'{key}' is already present in the registry. HINT: Use `override=True`.")
+        self[key] = cls
+
+    def register_classes(self, module: ModuleType, base_cls: Type, override: bool = False) -> None:
+        """This function is an utility to register all classes from a module."""
+        for _, cls in inspect.getmembers(module, predicate=inspect.isclass):
+            if issubclass(cls, base_cls) and cls != base_cls:
+                self(cls=cls, override=override)
+
+    @property
+    def names(self) -> List[str]:
+        """Returns the registered names."""
+        return list(self.keys())
+
+    @property
+    def classes(self) -> Tuple[Type, ...]:
+        """Returns the registered classes."""
+        return tuple(self.values())
+
+    def __str__(self) -> str:
+        return f"Registered objects: {self.names}"
+
+
+OPTIMIZER_REGISTRY = _Registry()
+OPTIMIZER_REGISTRY.register_classes(torch.optim, Optimizer)
+
+LR_SCHEDULER_REGISTRY = _Registry()
+LR_SCHEDULER_REGISTRY.register_classes(torch.optim.lr_scheduler, torch.optim.lr_scheduler._LRScheduler)
+
+
 class LightningArgumentParser(ArgumentParser):
     """Extension of jsonargparse's ArgumentParser for pytorch-lightning."""
 
+    # use class attribute because `parse_args` is only called on the main parser
+    _choices: Dict[str, Tuple[Type, ...]] = {}
+
     def __init__(self, *args: Any, parse_as_dict: bool = True, **kwargs: Any) -> None:
         """Initialize argument parser that supports configuration file input.
 
@@ -118,6 +170,7 @@ def add_optimizer_args(
         kwargs = {"instantiate": False, "fail_untyped": False, "skip": {"params"}}
         if isinstance(optimizer_class, tuple):
             self.add_subclass_arguments(optimizer_class, nested_key, **kwargs)
+            self.set_choices(nested_key, optimizer_class)
         else:
             self.add_class_arguments(optimizer_class, nested_key, **kwargs)
         self._optimizers[nested_key] = (optimizer_class, link_to)
@@ -142,10 +195,70 @@ def add_lr_scheduler_args(
         kwargs = {"instantiate": False, "fail_untyped": False, "skip": {"optimizer"}}
         if isinstance(lr_scheduler_class, tuple):
             self.add_subclass_arguments(lr_scheduler_class, nested_key, **kwargs)
+            self.set_choices(nested_key, lr_scheduler_class)
         else:
             self.add_class_arguments(lr_scheduler_class, nested_key, **kwargs)
         self._lr_schedulers[nested_key] = (lr_scheduler_class, link_to)
 
+    def parse_args(self, *args: Any, **kwargs: Any) -> Dict[str, Any]:
+        argv = sys.argv
+        for k, classes in self._choices.items():
+            if not any(arg.startswith(f"--{k}") for arg in argv):
+                # the key wasn't passed - maybe defined in a config, maybe it's optional
+                continue
+            argv = self._convert_argv_issue_84(classes, k, argv)
+        self._choices.clear()
+        with mock.patch("sys.argv", argv):
+            return super().parse_args(*args, **kwargs)
+
+    def set_choices(self, nested_key: str, classes: Tuple[Type, ...]) -> None:
+        self._choices[nested_key] = classes
+
+    @staticmethod
+    def _convert_argv_issue_84(classes: Tuple[Type, ...], nested_key: str, argv: List[str]) -> List[str]:
+        """Placeholder for https://github.com/omni-us/jsonargparse/issues/84.
+
+        This should be removed once implemented.
+        """
+        passed_args, clean_argv = {}, []
+        argv_key = f"--{nested_key}"
+        # get the argv args for this nested key
+        i = 0
+        while i < len(argv):
+            arg = argv[i]
+            if arg.startswith(argv_key):
+                if "=" in arg:
+                    key, value = arg.split("=")
+                else:
+                    key = arg
+                    i += 1
+                    value = argv[i]
+                passed_args[key] = value
+            else:
+                clean_argv.append(arg)
+            i += 1
+        # generate the associated config file
+        argv_class = passed_args.pop(argv_key, None)
+        if argv_class is None:
+            # the user passed a config as a str
+            class_path = passed_args[f"{argv_key}.class_path"]
+            init_args_key = f"{argv_key}.init_args"
+            init_args = {k[len(init_args_key) + 1 :]: v for k, v in passed_args.items() if k.startswith(init_args_key)}
+            config = str({"class_path": class_path, "init_args": init_args})
+        elif argv_class.startswith("{"):
+            # the user passed a config as a dict
+            config = argv_class
+        else:
+            # the user passed the shorthand format
+            init_args = {k[len(argv_key) + 1 :]: v for k, v in passed_args.items()}  # +1 to account for the period
+            for cls in classes:
+                if cls.__name__ == argv_class:
+                    config = str(_global_add_class_path(cls, init_args))
+                    break
+            else:
+                raise ValueError(f"Could not generate a config for {repr(argv_class)}")
+        return clean_argv + [argv_key, config]
+
 
 class SaveConfigCallback(Callback):
     """Saves a LightningCLI config to the log_dir when training starts.
@@ -328,6 +441,11 @@ def _add_arguments(self, parser: LightningArgumentParser) -> None:
         self.add_default_arguments_to_parser(parser)
         self.add_core_arguments_to_parser(parser)
         self.add_arguments_to_parser(parser)
+        # add default optimizer args if necessary
+        if not parser._optimizers:  # already added by the user in `add_arguments_to_parser`
+            parser.add_optimizer_args(OPTIMIZER_REGISTRY.classes)
+        if not parser._lr_schedulers:  # already added by the user in `add_arguments_to_parser`
+            parser.add_lr_scheduler_args(LR_SCHEDULER_REGISTRY.classes)
         self.link_optimizers_and_lr_schedulers(parser)
 
     def add_arguments_to_parser(self, parser: LightningArgumentParser) -> None:

requirements/extra.txt

@@ -7,6 +7,6 @@ torchtext>=0.7
 onnx>=1.7.0
 onnxruntime>=1.3.0
 hydra-core>=1.0
-jsonargparse[signatures]>=3.19.0
+jsonargparse[signatures]>=3.19.3
 gcsfs>=2021.5.0
 rich>=10.2.2