Refactor the objectives into PyTorch datasets (#9)

descent/data/__init__.py

@@ -0,0 +1,3 @@
+from descent.data.data import Dataset, DatasetEntry
+
+__all__ = [DatasetEntry, Dataset]

descent/data/data.py

@@ -0,0 +1,78 @@
+import abc
+from typing import Generic, Iterator, Sequence, TypeVar, Union
+
+import torch.utils.data
+from openff.interchange.components.interchange import Interchange
+from smirnoffee.smirnoff import vectorize_system
+
+from descent.models import ParameterizationModel
+from descent.models.models import VectorizedSystem
+
+T_co = TypeVar("T_co", covariant=True)
+
+
+class DatasetEntry(abc.ABC):
+    """The base class for storing labels associated with an input datum, such as
+    an OpenFF interchange object or an Espaloma graph model."""
+
+    @property
+    def model_input(self) -> VectorizedSystem:
+        return self._model_input
+
+    def __init__(self, model_input: Union[Interchange]):
+        """
+
+        Args:
+            model_input: The input that will be passed to the model being trained in
+                order to yield a vectorized view of a parameterised molecule. If the
+                input is an interchange object it will be vectorised prior to being
+                used as a model input.
+        """
+
+        self._model_input = (
+            model_input
+            if not isinstance(model_input, Interchange)
+            else vectorize_system(model_input)
+        )
+
+    @abc.abstractmethod
+    def evaluate_loss(self, model: ParameterizationModel, **kwargs) -> torch.Tensor:
+        """Evaluates the contribution to the total loss function of the data stored
+        in this entry using a specified model.
+
+        Args:
+            model: The model that will return vectorized view of a parameterised
+                molecule.
+
+        Returns:
+            The loss contribution of this entry.
+        """
+        raise NotImplementedError()
+
+    def __call__(self, model: ParameterizationModel, **kwargs) -> torch.Tensor:
+        """Evaluate the objective using a specified model.
+
+        Args:
+            model: The model that will return vectorized view of a parameterised
+                molecule.
+
+        Returns:
+            The loss contribution of this entry.
+        """
+        return self.evaluate_loss(model, **kwargs)
+
+
+class Dataset(torch.utils.data.IterableDataset[T_co], Generic[T_co]):
+    r"""An class representing a :class:`Dataset`."""
+
+    def __init__(self, entries: Sequence):
+        self._entries = entries
+
+    def __getitem__(self, index: int) -> T_co:
+        return self._entries[index]
+
+    def __iter__(self) -> Iterator[T_co]:
+        return self._entries.__iter__()
+
+    def __len__(self) -> int:
+        return len(self._entries)