feat: load model from file (#98)

Author: bassmang

src/vowpal_wabbit_next/workspace.py

@@ -135,7 +135,7 @@ def __init__(
             args (List[str]): VowpalWabbit command line options for configuring the model. An overall list can be found `here <https://vowpalwabbit.org/docs/vowpal_wabbit/python/latest/command_line_args.html>`_. Options which affect the driver are not supported. For example:
                 `--sort_features`, `--ngram`, `--feature_limit`, `--ignore`, `--extra_metrics`, `--dump_json_weights_experimental`
             model_data (Optional[bytes], optional): Bytes of a VW model to be loaded.
-            record_invert_hash (bool, optional): If true, the invert hash will be recorded for each example. This is required to use :py:meth:`vowpal_wabbit_next.Workspace.json_weights`. This will slow down parsing and learn/predict.
+            record_feature_names (bool, optional): If true, the invert hash will be recorded for each example. This is required to use :py:meth:`vowpal_wabbit_next.Workspace.json_weights`. This will slow down parsing and learn/predict.
             record_metrics (bool, optional): If true, reduction metrics will be enabled and can be fetched with :py:attr:`vowpal_wabbit_next.Workspace.metrics`
             enable_debug_tree (bool, optional): If true, debug information in the form of the computation tree will be emitted by :py:meth:`~vowpal_wabbit_next.learn_one`, :py:meth:`~vowpal_wabbit_next.predict_one` and :py:meth:`~vowpal_wabbit_next.predict_then_learn_one`. This will affect performance negatively. See :py:class:`~vowpal_wabbit_next.DebugNode` for more information.
 
@@ -335,6 +335,51 @@ def serialize(self) -> bytes:
         """
         return self._workspace.serialize()
 
+    @staticmethod
+    def load_from_file(
+        file_path: Union[str, os.PathLike[Any]],
+        args: List[str] = [],
+        *,
+        record_feature_names: bool = False,
+        record_metrics: bool = False,
+        enable_debug_tree: bool = False,
+    ) -> Workspace[Any]:
+        """Load a VW model from a file.
+
+        Args:
+            file_path (Union[str, os.PathLike[Any]]): Path to file containing serialized model
+            args (List[str]): VowpalWabbit command line options for configuring the model. An overall list can be found `here <https://vowpalwabbit.org/docs/vowpal_wabbit/python/latest/command_line_args.html>`_. Options which affect the driver are not supported. For example:
+                `--sort_features`, `--ngram`, `--feature_limit`, `--ignore`, `--extra_metrics`, `--dump_json_weights_experimental`
+            record_feature_names (bool, optional): If true, the invert hash will be recorded for each example. This is required to use :py:meth:`vowpal_wabbit_next.Workspace.json_weights`. This will slow down parsing and learn/predict.
+            record_metrics (bool, optional): If true, reduction metrics will be enabled and can be fetched with :py:attr:`vowpal_wabbit_next.Workspace.metrics`
+            enable_debug_tree (bool, optional): If true, debug information in the form of the computation tree will be emitted by :py:meth:`~vowpal_wabbit_next.learn_one`, :py:meth:`~vowpal_wabbit_next.predict_one` and :py:meth:`~vowpal_wabbit_next.predict_then_learn_one`. This will affect performance negatively. See :py:class:`~vowpal_wabbit_next.DebugNode` for more information.
+
+                    .. warning::
+                        This is an experimental feature.
+
+        Returns:
+            Workspace[Any]: Workspace with the loaded model
+        """
+        with open(file_path, "rb") as f:
+            model_data = f.read()
+
+        if enable_debug_tree:
+            return Workspace[Literal[True]](
+                args,
+                model_data=model_data,
+                record_feature_names=record_feature_names,
+                record_metrics=record_metrics,
+                enable_debug_tree=True,
+            )
+        else:
+            return Workspace[Literal[False]](
+                args,
+                model_data=model_data,
+                record_feature_names=record_feature_names,
+                record_metrics=record_metrics,
+                enable_debug_tree=False,
+            )
+
     def serialize_to_file(self, file_path: Union[str, os.PathLike[Any]]) -> None:
         """Serialize the current workspace as a VW model to a file."""
         return self._workspace.serialize_to_file(os.fspath(file_path))

tests/test_serialization.py

@@ -43,9 +43,7 @@ def test_serialize_to_file_and_load() -> None:
     model.serialize_to_file(model_path)
 
     try:
-        with open(model_path, "rb") as f:
-            model2 = vw.Workspace(model_data=f.read())
-
+        model2 = vw.Workspace.load_from_file(model_path)
         parser2 = vw.TextFormatParser(model)
         test_example2 = parser2.parse_line(test_example_input)
         pred2 = model2.predict_one(test_example2)