Orca pytorch estimator wrapper (intel-analytics#2624)

* add estimator wrapper

* fix testcase

* fix style

* delete testcase & modify example

python/orca/src/bigdl/orca/learn/pytorch/estimator.py

@@ -0,0 +1,118 @@
+#
+# Copyright 2018 Analytics Zoo Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+#
+from zoo.orca.learn.pytorch.training_operator import TrainingOperator
+from zoo.orca.learn.pytorch.pytorch_horovod_estimator import PyTorchHorovodEstimator
+
+
+class Estimator(object):
+    def fit(self, data, epochs, **kwargs):
+        pass
+
+    def predict(self, data, **kwargs):
+        pass
+
+    def evaluate(self, data, **kwargs):
+        pass
+
+    @staticmethod
+    def from_model_creator(*,
+                           model_creator,
+                           optimizer_creator,
+                           loss_creator=None,
+                           scheduler_creator=None,
+                           training_operator_cls=TrainingOperator,
+                           initialization_hook=None,
+                           config=None,
+                           scheduler_step_freq="batch",
+                           backend="ray"):
+        assert backend == "ray", "only ray backend is supported for now"
+        return PyTorchHorovodEstimatorWrapper(model_creator=model_creator,
+                                              optimizer_creator=optimizer_creator,
+                                              loss_creator=loss_creator,
+                                              scheduler_creator=scheduler_creator,
+                                              training_operator_cls=training_operator_cls,
+                                              initialization_hook=initialization_hook,
+                                              config=config,
+                                              scheduler_step_freq=scheduler_step_freq)
+
+
+class PyTorchHorovodEstimatorWrapper(Estimator):
+    def __init__(self,
+                 *,
+                 model_creator,
+                 optimizer_creator,
+                 loss_creator=None,
+                 scheduler_creator=None,
+                 training_operator_cls=TrainingOperator,
+                 initialization_hook=None,
+                 config=None,
+                 scheduler_step_freq="batch"):
+        self.estimator = PyTorchHorovodEstimator(model_creator=model_creator,
+                                                 optimizer_creator=optimizer_creator,
+                                                 loss_creator=loss_creator,
+                                                 scheduler_creator=scheduler_creator,
+                                                 training_operator_cls=training_operator_cls,
+                                                 initialization_hook=initialization_hook,
+                                                 config=config,
+                                                 scheduler_step_freq=scheduler_step_freq)
+
+    def fit(self, data, epochs=1, num_steps=None, profile=False, reduce_results=True, info=None):
+        """
+
+        :param data: (callable) a funtion that takes a config dict as input and return a data
+            loader containing the training data.
+        :param epochs: (int) Number of epochs to train the model
+        :param num_steps: (int) Number of batches to compute update steps on.
+            This corresponds also to the number of times `TrainingOperator.train_batch`` is called.
+        :param profile: (bool) Returns time stats for the training procedure.
+        :param reduce_results: (bool) Whether to average all metrics across all workers into one
+            dict. If a metric is a non-numerical value (or nested dictionaries), one value will be
+            randomly selected among the workers. If False, returns a list of dicts.
+        :param info: (dict) Optional dictionary passed to the training operator for ``train_epoch``
+            and ``train_batch``.
+        :return: (list) A list of stats whose length will be equal to ``epochs``.
+                stats is a dictionary of metrics for training.
+                    You can provide custom metrics by passing in a custom
+                    ``training_operator_cls``. If ``reduce_results=False``,
+                    this will return a list of metric dictionaries whose
+                    length will be equal to ``num_workers``.
+        """
+        stats_list = list()
+        for i in range(epochs):
+            stats = self.estimator.train(data_creator=data, num_steps=num_steps, profile=profile,
+                                         reduce_results=reduce_results, info=info)
+            stats_list.append(stats)
+        return stats_list
+
+    def predict(self, data, **kwargs):
+        pass
+
+    def evaluate(self, data, num_steps=None, profile=False, info=None):
+        """
+
+        :param data: (callable) a funtion that takes a config dict as input and return
+            a data loader containing the validation data.
+        :param num_steps: (int) Number of batches to compute update steps on.
+               This corresponds also to the number of times ``TrainingOperator.validate_batch``
+               is called.
+        :param profile: (bool) Returns time stats for the evaluation procedure.
+        :param info: (dict) Optional dictionary passed to the training operator for `validate`
+            and `validate_batch`.
+        :return: A dictionary of metrics for validation.
+            You can provide custom metrics by passing in a custom ``training_operator_cls``.
+        """
+        return self.estimator.validate(data_creator=data, num_steps=num_steps, profile=profile,
+                                       info=info)