RL4J: Add TransformProcess, part 1 (#8711)

* Added TransformProcess, part 1

Signed-off-by: unknown <aboulang2002@yahoo.com>

* Renamed TemporalMergeTransform to HistoryMergeTransform

Signed-off-by: unknown <aboulang2002@yahoo.com>

* changed INDArrayHelper to use Nd4j.expandDims

Signed-off-by: Alexandre Boulanger <aboulang2002@yahoo.com>

* Adjusted copyrights

Signed-off-by: unknown <aboulang2002@yahoo.com>

datavec/datavec-api/src/main/java/org/datavec/api/transform/ColumnOp.java

@@ -26,10 +26,7 @@ import org.datavec.api.transform.schema.Schema;
  *
  * @author Adam Gibson
  */
-public interface ColumnOp {
+public interface ColumnOp extends Operation<Schema, Schema> {
-    /** Get the output schema for this transformation, given an input schema */
-    Schema transform(Schema inputSchema);
-
 
     /** Set the input schema.
      */

datavec/datavec-api/src/main/java/org/datavec/api/transform/Operation.java

@@ -1,28 +1,20 @@
-/*******************************************************************************
+/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
+ * Copyright (c) 2020 Konduit K.K.
- *
+ *
- * This program and the accompanying materials are made available under the
+ * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
+ * terms of the Apache License, Version 2.0 which is available at
- * https://www.apache.org/licenses/LICENSE-2.0.
+ * https://www.apache.org/licenses/LICENSE-2.0.
- *
+ *
- * Unless required by applicable law or agreed to in writing, software
+ * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
+ * License for the specific language governing permissions and limitations
- * under the License.
+ * under the License.
- *
+ *
- * SPDX-License-Identifier: Apache-2.0
+ * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
+ ******************************************************************************/
-
+package org.datavec.api.transform;
-package org.deeplearning4j.rl4j.observation.preprocessor;
+
-
+public interface Operation<TIn, TOut> {
-import org.nd4j.linalg.dataset.api.DataSetPreProcessor;
+    TOut transform(TIn input);
-
+}
-/**
- * A base class for all DataSetPreProcessor that must be reset between each MDP sessions (games).
- *
- * @author Alexandre Boulanger
- */
-public abstract class ResettableDataSetPreProcessor implements DataSetPreProcessor {
-    public abstract void reset();
-}

datavec/datavec-data/datavec-data-image/src/main/java/org/datavec/image/transform/ImageTransform.java

@@ -16,6 +16,7 @@
 
 package org.datavec.image.transform;
 
+import org.datavec.api.transform.Operation;
 import org.datavec.image.data.ImageWritable;
 import org.nd4j.shade.jackson.annotation.JsonInclude;
 import org.nd4j.shade.jackson.annotation.JsonTypeInfo;
@@ -29,15 +30,7 @@ import java.util.Random;
  */
 @JsonInclude(JsonInclude.Include.NON_NULL)
 @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
-public interface ImageTransform {
+public interface ImageTransform extends Operation<ImageWritable, ImageWritable>  {
-
-    /**
-     * Takes an image and returns a transformed image.
-     *
-     * @param image to transform, null == end of stream
-     * @return      transformed image
-     */
-    ImageWritable transform(ImageWritable image);
 
     /**
      * Takes an image and returns a transformed image.

rl4j/rl4j-core/pom.xml

@@ -102,6 +102,13 @@
             <artifactId>gson</artifactId>
             <version>${gson.version}</version>
         </dependency>
+
+        <dependency>
+            <groupId>org.datavec</groupId>
+            <artifactId>datavec-api</artifactId>
+            <version>${datavec.version}</version>
+        </dependency>
+
     </dependencies>
 
     <profiles>

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/helper/INDArrayHelper.java

@@ -1,30 +1,39 @@
-/*******************************************************************************
+/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
+ * Copyright (c) 2020 Konduit K.K.
- *
+ *
- * This program and the accompanying materials are made available under the
+ * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
+ * terms of the Apache License, Version 2.0 which is available at
- * https://www.apache.org/licenses/LICENSE-2.0.
+ * https://www.apache.org/licenses/LICENSE-2.0.
- *
+ *
- * Unless required by applicable law or agreed to in writing, software
+ * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
+ * License for the specific language governing permissions and limitations
- * under the License.
+ * under the License.
- *
+ *
- * SPDX-License-Identifier: Apache-2.0
+ * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
+ ******************************************************************************/
-
+package org.deeplearning4j.rl4j.helper;
-package org.deeplearning4j.rl4j.observation.preprocessor.pooling;
+
-
+import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
-
+
-/**
+/**
- * A PoolContentAssembler is used with the PoolingDataSetPreProcessor. This interface defines how the array of INDArray
+ * INDArray helper methods used by RL4J
- * returned by the ObservationPool is packaged into the single INDArray that will be set
+ *
- * in the DataSet of PoolingDataSetPreProcessor.preProcess
+ * @author Alexandre Boulanger
- *
+ */
- * @author Alexandre Boulanger
+public class INDArrayHelper {
- */
+    /**
-public interface PoolContentAssembler {
+     * MultiLayerNetwork and ComputationGraph expect the first dimension to be the number of examples in the INDArray.
-    INDArray assemble(INDArray[] poolContent);
+     * In the case of RL4J, it must be 1. This method will return a INDArray with the correct shape.
-}
+     *
+     * @param source A INDArray
+     * @return The source INDArray with the correct shape
+     */
+    public static INDArray forceCorrectShape(INDArray source) {
+        return source.shape()[0] == 1
+                ? source
+                : Nd4j.expandDims(source, 0);
+    }
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/learning/async/AsyncThreadDiscrete.java

@@ -90,7 +90,7 @@ public abstract class AsyncThreadDiscrete<O, NN extends NeuralNet>
             accuReward += stepReply.getReward() * getConf().getRewardFactor();
 
             //if it's not a skipped frame, you can do a step of training
-            if (!obs.isSkipped() || stepReply.isDone()) {
+            if (!obs.isSkipped()) {
 
                 INDArray[] output = current.outputAll(obs.getData());
                 rewards.add(new MiniTrans(obs.getData(), action, output, accuReward));
@@ -99,7 +99,6 @@ public abstract class AsyncThreadDiscrete<O, NN extends NeuralNet>
             }
 
             obs = stepReply.getObservation();
-
             reward += stepReply.getReward();
 
             incrementStep();

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/learning/sync/qlearning/discrete/QLearningDiscrete.java

@@ -158,7 +158,7 @@ public abstract class QLearningDiscrete<O extends Encodable> extends QLearning<O
         accuReward += stepReply.getReward() * configuration.getRewardFactor();
 
         //if it's not a skipped frame, you can do a step of training
-        if (!obs.isSkipped() || stepReply.isDone()) {
+        if (!obs.isSkipped()) {
 
             // Add experience
             if(pendingTransition != null) {

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/preprocessor/PoolingDataSetPreProcessor.java

@@ -1,130 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
- * https://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.
- *
- * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
-
-package org.deeplearning4j.rl4j.observation.preprocessor;
-
-import org.deeplearning4j.rl4j.observation.preprocessor.pooling.ChannelStackPoolContentAssembler;
-import org.deeplearning4j.rl4j.observation.preprocessor.pooling.PoolContentAssembler;
-import org.deeplearning4j.rl4j.observation.preprocessor.pooling.CircularFifoObservationPool;
-import org.deeplearning4j.rl4j.observation.preprocessor.pooling.ObservationPool;
-import org.nd4j.base.Preconditions;
-import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.dataset.api.DataSet;
-
-/**
- * The PoolingDataSetPreProcessor will accumulate features from incoming DataSets and will assemble its content
- * into a DataSet containing a single example.
- *
- * There are two special cases:
- *    1) preProcess will return without doing anything if the input DataSet is empty
- *    2) When the pool has not yet filled, the data from the incoming DataSet is stored in the pool but the DataSet is emptied
- *       on exit.
- * <br>
- * The PoolingDataSetPreProcessor requires two sub components: <br>
- *    1) The ObservationPool that supervises what and how input observations are kept. (ex.: Circular FIFO, trailing min/max/avg, etc...)
- *       The default is a Circular FIFO.
- *    2) The PoolContentAssembler that will assemble the pool content into a resulting single INDArray. (ex.: stacked along a dimention, squashed into a single observation, etc...)
- *       The default is stacking along the dimension 0.
- *
- * @author Alexandre Boulanger
- */
-public class PoolingDataSetPreProcessor extends ResettableDataSetPreProcessor {
-    private final ObservationPool observationPool;
-    private final PoolContentAssembler poolContentAssembler;
-
-    protected PoolingDataSetPreProcessor(PoolingDataSetPreProcessor.Builder builder)
-    {
-        observationPool = builder.observationPool;
-        poolContentAssembler = builder.poolContentAssembler;
-    }
-
-    /**
-     * Note: preProcess will empty the processed dataset if the pool has not filled. Empty datasets should ignored by the
-     * Policy/Learning class and other DataSetPreProcessors
-     *
-     * @param dataSet
-     */
-    @Override
-    public void preProcess(DataSet dataSet) {
-        Preconditions.checkNotNull(dataSet, "Encountered null dataSet");
-
-        if(dataSet.isEmpty()) {
-            return;
-        }
-
-        Preconditions.checkArgument(dataSet.numExamples() == 1, "Pooling datasets conatining more than one example is not supported");
-
-        // store a duplicate in the pool
-        observationPool.add(dataSet.getFeatures().slice(0, 0).dup());
-        if(!observationPool.isAtFullCapacity()) {
-            dataSet.setFeatures(null);
-            return;
-        }
-
-        INDArray result = poolContentAssembler.assemble(observationPool.get());
-
-        // return a DataSet containing only 1 example (the result)
-        long[] resultShape = result.shape();
-        long[] newShape = new long[resultShape.length + 1];
-        newShape[0] = 1;
-        System.arraycopy(resultShape, 0, newShape, 1, resultShape.length);
-
-        dataSet.setFeatures(result.reshape(newShape));
-    }
-
-    public static PoolingDataSetPreProcessor.Builder builder() {
-        return new PoolingDataSetPreProcessor.Builder();
-    }
-
-    @Override
-    public void reset() {
-        observationPool.reset();
-    }
-
-    public static class Builder {
-        private ObservationPool observationPool;
-        private PoolContentAssembler poolContentAssembler;
-
-        /**
-         * Default is CircularFifoObservationPool
-         */
-        public PoolingDataSetPreProcessor.Builder observablePool(ObservationPool observationPool) {
-            this.observationPool = observationPool;
-            return this;
-        }
-
-        /**
-         * Default is ChannelStackPoolContentAssembler
-         */
-        public PoolingDataSetPreProcessor.Builder poolContentAssembler(PoolContentAssembler poolContentAssembler) {
-            this.poolContentAssembler = poolContentAssembler;
-            return this;
-        }
-
-        public PoolingDataSetPreProcessor build() {
-            if(observationPool == null) {
-                observationPool = new CircularFifoObservationPool();
-            }
-
-            if(poolContentAssembler == null) {
-                poolContentAssembler = new ChannelStackPoolContentAssembler();
-            }
-
-            return new PoolingDataSetPreProcessor(this);
-        }
-    }
-
-}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/preprocessor/SkippingDataSetPreProcessor.java

@@ -1,62 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
- * https://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.
- *
- * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
-
-package org.deeplearning4j.rl4j.observation.preprocessor;
-
-import lombok.Builder;
-import org.nd4j.base.Preconditions;
-import org.nd4j.linalg.dataset.api.DataSet;
-
-/**
- * The SkippingDataSetPreProcessor will either do nothing to the input (when not skipped) or will empty
- * the input DataSet when skipping.
- *
- * @author Alexandre Boulanger
- */
-public class SkippingDataSetPreProcessor extends ResettableDataSetPreProcessor {
-
-    private final int skipFrame;
-
-    private int currentIdx = 0;
-
-    /**
-     * @param skipFrame For example, a skipFrame of 4 will skip 3 out of 4 observations.
-     */
-    @Builder
-    public SkippingDataSetPreProcessor(int skipFrame) {
-        Preconditions.checkArgument(skipFrame > 0, "skipFrame must be greater than 0, got %s", skipFrame);
-        this.skipFrame = skipFrame;
-    }
-
-    @Override
-    public void preProcess(DataSet dataSet) {
-        Preconditions.checkNotNull(dataSet, "Encountered null dataSet");
-
-        if(dataSet.isEmpty()) {
-            return;
-        }
-
-        if(currentIdx++ % skipFrame != 0) {
-            dataSet.setFeatures(null);
-            dataSet.setLabels(null);
-        }
-    }
-
-    @Override
-    public void reset() {
-        currentIdx = 0;
-    }
-}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/FilterOperation.java

@@ -0,0 +1,35 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform;
+
+import java.util.Map;
+
+/**
+ * Used with {@link TransformProcess TransformProcess} to filter-out an observation.
+ *
+ * @author Alexandre Boulanger
+ */
+public interface FilterOperation {
+    /**
+     * The logic that determines if the observation should be skipped.
+     *
+     * @param channelsData the name of the channel
+     * @param currentObservationStep The step number if the observation in the current episode.
+     * @param isFinalObservation true if this is the last observation of the episode
+     * @return true if the observation should be skipped
+     */
+    boolean isSkipped(Map<String, Object> channelsData, int currentObservationStep, boolean isFinalObservation);
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/ResettableOperation.java

@@ -1,32 +1,26 @@
-/*******************************************************************************
+/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
+ * Copyright (c) 2020 Konduit K.K.
- *
+ *
- * This program and the accompanying materials are made available under the
+ * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
+ * terms of the Apache License, Version 2.0 which is available at
- * https://www.apache.org/licenses/LICENSE-2.0.
+ * https://www.apache.org/licenses/LICENSE-2.0.
- *
+ *
- * Unless required by applicable law or agreed to in writing, software
+ * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
+ * License for the specific language governing permissions and limitations
- * under the License.
+ * under the License.
- *
+ *
- * SPDX-License-Identifier: Apache-2.0
+ * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
+ ******************************************************************************/
-
+package org.deeplearning4j.rl4j.observation.transform;
-package org.deeplearning4j.rl4j.observation.preprocessor.pooling;
+
-
+/**
-import org.nd4j.linalg.api.ndarray.INDArray;
+ * The {@link TransformProcess TransformProcess} will call reset() (at the start of an episode) of any step that implement this interface.
-
+ */
-/**
+public interface ResettableOperation {
- * ObservationPool is used with the PoolingDataSetPreProcessor. Used to supervise how data from the
+    /**
- * PoolingDataSetPreProcessor is stored.
+     * Called by TransformProcess when an episode starts. See {@link TransformProcess#reset() TransformProcess.reset()}
- *
+     */
- * @author Alexandre Boulanger
+    void reset();
- */
+}
-public interface ObservationPool {
-    void add(INDArray observation);
-    INDArray[] get();
-    boolean isAtFullCapacity();
-    void reset();
-}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/filter/UniformSkippingFilter.java

@@ -0,0 +1,45 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform.filter;
+
+import org.deeplearning4j.rl4j.observation.transform.FilterOperation;
+import org.nd4j.base.Preconditions;
+import java.util.Map;
+
+/**
+ * Used with {@link org.deeplearning4j.rl4j.observation.transform.TransformProcess TransformProcess}. Will cause the
+ * transform process to skip a fixed number of frames between non skipped ones.
+ *
+ * @author Alexandre Boulanger
+ */
+public class UniformSkippingFilter implements FilterOperation {
+
+    private final int skipFrame;
+
+    /**
+     * @param skipFrame Will cause the filter to keep (not skip) 1 frame every skipFrames.
+     */
+    public UniformSkippingFilter(int skipFrame) {
+        Preconditions.checkArgument(skipFrame > 0, "skipFrame should be greater than 0");
+
+        this.skipFrame = skipFrame;
+    }
+
+    @Override
+    public boolean isSkipped(Map<String, Object> channelsData, int currentObservationStep, boolean isFinalObservation) {
+        return !isFinalObservation && (currentObservationStep % skipFrame != 0);
+    }
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/legacy/EncodableToINDArrayTransform.java

@@ -0,0 +1,41 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform.legacy;
+
+import org.bytedeco.javacv.OpenCVFrameConverter;
+import org.bytedeco.opencv.opencv_core.Mat;
+import org.datavec.api.transform.Operation;
+import org.datavec.image.data.ImageWritable;
+import org.deeplearning4j.rl4j.space.Encodable;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import static org.bytedeco.opencv.global.opencv_core.CV_32FC;
+
+public class EncodableToINDArrayTransform implements Operation<Encodable, INDArray> {
+
+    private final int[] shape;
+
+    public EncodableToINDArrayTransform(int[] shape) {
+        this.shape = shape;
+    }
+
+    @Override
+    public INDArray transform(Encodable encodable) {
+        return Nd4j.create(encodable.toArray()).reshape(shape);
+    }
+
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/legacy/EncodableToImageWriteableTransform.java

@@ -0,0 +1,48 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform.legacy;
+
+import org.bytedeco.javacv.OpenCVFrameConverter;
+import org.bytedeco.opencv.opencv_core.Mat;
+import org.datavec.api.transform.Operation;
+import org.datavec.image.data.ImageWritable;
+import org.deeplearning4j.rl4j.space.Encodable;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import static org.bytedeco.opencv.global.opencv_core.CV_32FC;
+
+public class EncodableToImageWriteableTransform implements Operation<Encodable, ImageWritable> {
+
+    private final OpenCVFrameConverter.ToMat converter = new OpenCVFrameConverter.ToMat();
+    private final int height;
+    private final int width;
+    private final int colorChannels;
+
+    public EncodableToImageWriteableTransform(int height, int width, int colorChannels) {
+        this.height = height;
+        this.width = width;
+        this.colorChannels = colorChannels;
+    }
+
+    @Override
+    public ImageWritable transform(Encodable encodable) {
+        INDArray indArray = Nd4j.create((encodable).toArray()).reshape(height, width, colorChannels);
+        Mat mat = new Mat(height, width, CV_32FC(3), indArray.data().pointer());
+        return new ImageWritable(converter.convert(mat));
+    }
+
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/legacy/ImageWriteableToINDArrayTransform.java

@@ -0,0 +1,37 @@
+package org.deeplearning4j.rl4j.observation.transform.legacy;
+
+import org.datavec.api.transform.Operation;
+import org.datavec.image.data.ImageWritable;
+import org.datavec.image.loader.NativeImageLoader;
+import org.deeplearning4j.rl4j.space.Encodable;
+import org.nd4j.linalg.api.buffer.DataType;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import java.io.IOException;
+
+public class ImageWriteableToINDArrayTransform implements Operation<ImageWritable, INDArray> {
+
+    private final int height;
+    private final int width;
+    private final NativeImageLoader loader;
+
+    public ImageWriteableToINDArrayTransform(int height, int width) {
+        this.height = height;
+        this.width = width;
+        this.loader = new NativeImageLoader(height, width);
+    }
+
+    @Override
+    public INDArray transform(ImageWritable imageWritable) {
+        INDArray out = null;
+        try {
+            out = loader.asMatrix(imageWritable);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        out = out.reshape(1, height, width);
+        INDArray compressed = out.castTo(DataType.UINT8);
+        return compressed;
+    }
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/operation/HistoryMergeTransform.java

@@ -0,0 +1,147 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform.operation;
+
+import org.datavec.api.transform.Operation;
+import org.deeplearning4j.rl4j.helper.INDArrayHelper;
+import org.deeplearning4j.rl4j.observation.transform.ResettableOperation;
+import org.deeplearning4j.rl4j.observation.transform.operation.historymerge.CircularFifoStore;
+import org.deeplearning4j.rl4j.observation.transform.operation.historymerge.HistoryMergeAssembler;
+import org.deeplearning4j.rl4j.observation.transform.operation.historymerge.HistoryMergeElementStore;
+import org.deeplearning4j.rl4j.observation.transform.operation.historymerge.HistoryStackAssembler;
+import org.nd4j.linalg.api.ndarray.INDArray;
+
+/**
+ * The HistoryMergeTransform will accumulate features from incoming INDArrays and will assemble its content
+ * into a new INDArray containing a single example.
+ *
+ * This is used in scenarios where motion in an important element.
+ *
+ * There is a special case:
+ *    * When the store is not full (not ready), the data from the incoming INDArray is stored but null is returned (will be interpreted as a skipped observation)
+ * <br>
+ * The HistoryMergeTransform requires two sub components: <br>
+ *    1) The {@link HistoryMergeElementStore HistoryMergeElementStore} that supervises what and how input INDArrays are kept. (ex.: Circular FIFO, trailing min/max/avg, etc...)
+ *       The default is a Circular FIFO.
+ *    2) The {@link HistoryMergeAssembler HistoryMergeAssembler} that will assemble the store content into a resulting single INDArray. (ex.: stacked along a dimension, squashed into a single observation, etc...)
+ *       The default is stacking along the dimension 0.
+ *
+ * @author Alexandre Boulanger
+ */
+public class HistoryMergeTransform implements Operation<INDArray, INDArray>, ResettableOperation {
+
+    private final HistoryMergeElementStore historyMergeElementStore;
+    private final HistoryMergeAssembler historyMergeAssembler;
+    private final boolean shouldStoreCopy;
+    private final boolean isFirstDimenstionBatch;
+
+    private HistoryMergeTransform(Builder builder) {
+        this.historyMergeElementStore = builder.historyMergeElementStore;
+        this.historyMergeAssembler = builder.historyMergeAssembler;
+        this.shouldStoreCopy = builder.shouldStoreCopy;
+        this.isFirstDimenstionBatch = builder.isFirstDimenstionBatch;
+    }
+
+    @Override
+    public INDArray transform(INDArray input) {
+        INDArray element;
+        if(isFirstDimenstionBatch) {
+            element = input.slice(0, 0);
+        }
+        else {
+            element = input;
+        }
+
+        if(shouldStoreCopy) {
+            element = element.dup();
+        }
+
+        historyMergeElementStore.add(element);
+        if(!historyMergeElementStore.isReady()) {
+            return null;
+        }
+
+        INDArray result = historyMergeAssembler.assemble(historyMergeElementStore.get());
+
+        return INDArrayHelper.forceCorrectShape(result);
+    }
+
+    @Override
+    public void reset() {
+        historyMergeElementStore.reset();
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+        private HistoryMergeElementStore historyMergeElementStore;
+        private HistoryMergeAssembler historyMergeAssembler;
+        private boolean shouldStoreCopy = false;
+        private boolean isFirstDimenstionBatch = false;
+
+        /**
+         * Default is {@link CircularFifoStore CircularFifoStore}
+         */
+        public Builder elementStore(HistoryMergeElementStore store) {
+            this.historyMergeElementStore = store;
+            return this;
+        }
+
+        /**
+         * Default is {@link HistoryStackAssembler HistoryStackAssembler}
+         */
+        public Builder assembler(HistoryMergeAssembler assembler) {
+            this.historyMergeAssembler = assembler;
+            return this;
+        }
+
+        /**
+         * If true, tell the HistoryMergeTransform to store copies of incoming INDArrays.
+         * (To prevent later in-place changes to a stored INDArray from changing what has been stored)
+         *
+         * Default is false
+         */
+        public Builder shouldStoreCopy(boolean shouldStoreCopy) {
+            this.shouldStoreCopy = shouldStoreCopy;
+            return this;
+        }
+
+        /**
+         * If true, tell the HistoryMergeTransform that the first dimension of the input INDArray is the batch count.
+         * When this is the case, the HistoryMergeTransform will slice the input like this [batch, height, width] -> [height, width]
+         *
+         * Default is false
+         */
+        public Builder isFirstDimenstionBatch(boolean isFirstDimenstionBatch) {
+            this.isFirstDimenstionBatch = isFirstDimenstionBatch;
+            return this;
+        }
+
+        public HistoryMergeTransform build() {
+            if(historyMergeElementStore == null) {
+                historyMergeElementStore = new CircularFifoStore();
+            }
+
+            if(historyMergeAssembler == null) {
+                historyMergeAssembler = new HistoryStackAssembler();
+            }
+
+            return new HistoryMergeTransform(this);
+        }
+    }
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/operation/historymerge/CircularFifoStore.java

@@ -1,95 +1,82 @@
-/*******************************************************************************
+/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
+ * Copyright (c) 2020 Konduit K.K.
- *
+ *
- * This program and the accompanying materials are made available under the
+ * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
+ * terms of the Apache License, Version 2.0 which is available at
- * https://www.apache.org/licenses/LICENSE-2.0.
+ * https://www.apache.org/licenses/LICENSE-2.0.
- *
+ *
- * Unless required by applicable law or agreed to in writing, software
+ * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
+ * License for the specific language governing permissions and limitations
- * under the License.
+ * under the License.
- *
+ *
- * SPDX-License-Identifier: Apache-2.0
+ * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
+ ******************************************************************************/
-
+package org.deeplearning4j.rl4j.observation.transform.operation.historymerge;
-package org.deeplearning4j.rl4j.observation.preprocessor.pooling;
+
-
+import org.apache.commons.collections4.queue.CircularFifoQueue;
-import org.apache.commons.collections4.queue.CircularFifoQueue;
+import org.deeplearning4j.rl4j.observation.transform.operation.HistoryMergeTransform;
-import org.nd4j.base.Preconditions;
+import org.nd4j.base.Preconditions;
-import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.factory.Nd4j;
+import org.nd4j.linalg.factory.Nd4j;
-
+
-/**
+/**
- * CircularFifoObservationPool is used with the PoolingDataSetPreProcessor. This pool is a first-in first-out queue
+ * CircularFifoStore is used with the {@link HistoryMergeTransform HistoryMergeTransform}. This store is a first-in first-out queue
- * with a fixed size that replaces its oldest element if full.
+ * with a fixed size that replaces its oldest element if full.
- *
+ *
- * @author Alexandre Boulanger
+ * @author Alexandre Boulanger
- */
+ */
-public class CircularFifoObservationPool implements ObservationPool {
+public class CircularFifoStore implements HistoryMergeElementStore {
-    private static final int DEFAULT_POOL_SIZE = 4;
+    private static final int DEFAULT_STORE_SIZE = 4;
-
+
-    private final CircularFifoQueue<INDArray> queue;
+    private final CircularFifoQueue<INDArray> queue;
-
+
-    private CircularFifoObservationPool(Builder builder) {
+    public CircularFifoStore() {
-        queue = new CircularFifoQueue<>(builder.poolSize);
+        this(DEFAULT_STORE_SIZE);
-    }
+    }
-
+
-    public CircularFifoObservationPool()
+    public CircularFifoStore(int size) {
-    {
+        Preconditions.checkArgument(size > 0, "The size must be at least 1, got %s", size);
-        this(DEFAULT_POOL_SIZE);
+        queue = new CircularFifoQueue<>(size);
-    }
+    }
-
+
-    public CircularFifoObservationPool(int poolSize)
+    /**
-    {
+     * Add an element to the store, if this addition would make the store to overflow, the new element replaces the oldest.
-        Preconditions.checkArgument(poolSize > 0, "The pool size must be at least 1, got %s", poolSize);
+     * @param elem
-        queue = new CircularFifoQueue<>(poolSize);
+     */
-    }
+    @Override
-
+    public void add(INDArray elem) {
-    /**
+        queue.add(elem);
-     * Add an element to the pool, if this addition would make the pool to overflow, the added element replaces the oldest one.
+    }
-     * @param elem
+
-     */
+    /**
-    public void add(INDArray elem) {
+     * @return The content of the store, returned in order from oldest to newest.
-        queue.add(elem);
+     */
-    }
+    @Override
-
+    public INDArray[] get() {
-    /**
+        int size = queue.size();
-     * @return The content of the pool, returned in order from oldest to newest.
+        INDArray[] array = new INDArray[size];
-     */
+        for (int i = 0; i < size; ++i) {
-    public INDArray[] get() {
+            array[i] = queue.get(i).castTo(Nd4j.dataType());
-        int size = queue.size();
+        }
-        INDArray[] array = new INDArray[size];
+        return array;
-        for (int i = 0; i < size; ++i) {
+    }
-            array[i] = queue.get(i).castTo(Nd4j.dataType());
+
-        }
+    /**
-        return array;
+     * The CircularFifoStore needs to be completely filled before being ready.
-    }
+     * @return false when the number of elements in the store is less than the store capacity (default is 4)
-
+     */
-    public boolean isAtFullCapacity() {
+    @Override
-        return queue.isAtFullCapacity();
+    public boolean isReady() {
-    }
+        return queue.isAtFullCapacity();
-
+    }
-    @Override
+
-    public void reset() {
+    /**
-        queue.clear();
+     * Clears the store.
-    }
+     */
-
+    @Override
-    public static Builder builder() {
+    public void reset() {
-        return new Builder();
+        queue.clear();
-    }
+    }
-
+}
-    public static class Builder {
-        private int poolSize = DEFAULT_POOL_SIZE;
-
-        public Builder poolSize(int poolSize) {
-            this.poolSize = poolSize;
-            return this;
-        }
-
-        public CircularFifoObservationPool build() {
-            return new CircularFifoObservationPool(this);
-        }
-    }
-}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/operation/historymerge/HistoryMergeAssembler.java

@@ -0,0 +1,35 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform.operation.historymerge;
+
+import org.deeplearning4j.rl4j.observation.transform.operation.HistoryMergeTransform;
+import org.nd4j.linalg.api.ndarray.INDArray;
+
+/**
+ * A HistoryMergeAssembler is used with the {@link HistoryMergeTransform HistoryMergeTransform}. This interface defines how the array of INDArray
+ * given by the {@link HistoryMergeElementStore HistoryMergeElementStore} is packaged into the single INDArray that will be
+ * returned by the HistoryMergeTransform
+ *
+ * @author Alexandre Boulanger
+ */
+public interface HistoryMergeAssembler {
+    /**
+     * Assemble an array of INDArray into a single INArray
+     * @param elements The input INDArray[]
+     * @return the assembled INDArray
+     */
+    INDArray assemble(INDArray[] elements);
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/operation/historymerge/HistoryMergeElementStore.java

@@ -0,0 +1,51 @@
+/*******************************************************************************
+ * Copyright (c) 2020 Konduit K.K.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+package org.deeplearning4j.rl4j.observation.transform.operation.historymerge;
+
+import org.deeplearning4j.rl4j.observation.transform.operation.HistoryMergeTransform;
+import org.nd4j.linalg.api.ndarray.INDArray;
+
+/**
+ * HistoryMergeElementStore is used with the {@link HistoryMergeTransform HistoryMergeTransform}. Used to supervise how data from the
+ * HistoryMergeTransform is stored.
+ *
+ * @author Alexandre Boulanger
+ */
+public interface HistoryMergeElementStore {
+    /**
+     * Add an element into the store
+     * @param observation
+     */
+    void add(INDArray observation);
+
+    /**
+     * Get the content of the store
+     * @return the content of the store
+     */
+    INDArray[] get();
+
+    /**
+     * Used to tell the HistoryMergeTransform that the store is ready. The HistoryMergeTransform will tell the {@link org.deeplearning4j.rl4j.observation.transform.TransformProcess TransformProcess}
+     * to skip the observation is the store is not ready.
+     * @return true if the store is ready
+     */
+    boolean isReady();
+
+    /**
+     * Resets the store to an initial state.
+     */
+    void reset();
+}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/observation/transform/operation/historymerge/HistoryStackAssembler.java

@@ -1,53 +1,52 @@
-/*******************************************************************************
+/*******************************************************************************
- * Copyright (c) 2015-2019 Skymind, Inc.
+ * Copyright (c) 2020 Konduit K.K.
- *
+ *
- * This program and the accompanying materials are made available under the
+ * This program and the accompanying materials are made available under the
- * terms of the Apache License, Version 2.0 which is available at
+ * terms of the Apache License, Version 2.0 which is available at
- * https://www.apache.org/licenses/LICENSE-2.0.
+ * https://www.apache.org/licenses/LICENSE-2.0.
- *
+ *
- * Unless required by applicable law or agreed to in writing, software
+ * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations
+ * License for the specific language governing permissions and limitations
- * under the License.
+ * under the License.
- *
+ *
- * SPDX-License-Identifier: Apache-2.0
+ * SPDX-License-Identifier: Apache-2.0
- ******************************************************************************/
+ ******************************************************************************/
-
+
-package org.deeplearning4j.rl4j.observation.preprocessor.pooling;
+package org.deeplearning4j.rl4j.observation.transform.operation.historymerge;
-
+
-import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.factory.Nd4j;
+import org.nd4j.linalg.factory.Nd4j;
-
+
-/**
+/**
- * ChannelStackPoolContentAssembler is used with the PoolingDataSetPreProcessor. This assembler will
+ * HistoryStackAssembler is used with the HistoryMergeTransform. This assembler will
- * stack along the dimension 0. For example if the pool elements are of shape [ Height, Width ]
+ * stack along the dimension 0. For example if the store elements are of shape [ Height, Width ]
- * the output will be of shape [ Stacked, Height, Width ]
+ * the output will be of shape [ Stacked, Height, Width ]
- *
+ *
- * @author Alexandre Boulanger
+ * @author Alexandre Boulanger
- */
+ */
-public class ChannelStackPoolContentAssembler implements PoolContentAssembler {
+public class HistoryStackAssembler implements HistoryMergeAssembler {
-
+
-    /**
+    /**
-     * Will return a new INDArray with one more dimension and with poolContent stacked along dimension 0.
+     * Will return a new INDArray with one more dimension and with elements stacked along dimension 0.
-     *
+     *
-     * @param poolContent Array of INDArray
+     * @param elements Array of INDArray
-     * @return A new INDArray with 1 more dimension than the input elements
+     * @return A new INDArray with 1 more dimension than the input elements
-     */
+     */
-    @Override
+    @Override
-    public INDArray assemble(INDArray[] poolContent)
+    public INDArray assemble(INDArray[] elements) {
-    {
+        // build the new shape
-        // build the new shape
+        long[] elementShape = elements[0].shape();
-        long[] elementShape = poolContent[0].shape();
+        long[] newShape = new long[elementShape.length + 1];
-        long[] newShape = new long[elementShape.length + 1];
+        newShape[0] = elements.length;
-        newShape[0] = poolContent.length;
+        System.arraycopy(elementShape, 0, newShape, 1, elementShape.length);
-        System.arraycopy(elementShape, 0, newShape, 1, elementShape.length);
+
-
+        // stack the elements in result on the dimension 0
-        // put pool elements in result
+        INDArray result = Nd4j.create(newShape);
-        INDArray result = Nd4j.create(newShape);
+        for(int i = 0; i < elements.length; ++i) {
-        for(int i = 0; i < poolContent.length; ++i) {
+            result.putRow(i, elements[i]);
-            result.putRow(i, poolContent[i]);
+        }
-        }
+        return result;
-        return result;
+    }
-    }
+}
-}

rl4j/rl4j-core/src/main/java/org/deeplearning4j/rl4j/policy/Policy.java

@@ -89,7 +89,7 @@ public abstract class Policy<O, A> implements IPolicy<O, A> {
         getNeuralNet().reset();
     }
 
-    private <AS extends ActionSpace<A>> Learning.InitMdp<Observation> refacInitMdp(LegacyMDPWrapper<O, A, AS> mdpWrapper, IHistoryProcessor hp, RefacEpochStepCounter epochStepCounter) {
+    protected <AS extends ActionSpace<A>> Learning.InitMdp<Observation> refacInitMdp(LegacyMDPWrapper<O, A, AS> mdpWrapper, IHistoryProcessor hp, RefacEpochStepCounter epochStepCounter) {
         epochStepCounter.setCurrentEpochStep(0);
 
         double reward = 0;

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/helper/INDArrayHelperTest.java

@@ -0,0 +1,38 @@
+package org.deeplearning4j.rl4j.helper;
+
+import org.junit.Test;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import static org.junit.Assert.*;
+
+public class INDArrayHelperTest {
+    @Test
+    public void when_inputHasIncorrectShape_expect_outputWithCorrectShape() {
+        // Arrange
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0});
+
+        // Act
+        INDArray output = INDArrayHelper.forceCorrectShape(input);
+
+        // Assert
+        assertEquals(2, output.shape().length);
+        assertEquals(1, output.shape()[0]);
+        assertEquals(3, output.shape()[1]);
+    }
+
+    @Test
+    public void when_inputHasCorrectShape_expect_outputWithSameShape() {
+        // Arrange
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0}).reshape(1, 3);
+
+        // Act
+        INDArray output = INDArrayHelper.forceCorrectShape(input);
+
+        // Assert
+        assertEquals(2, output.shape().length);
+        assertEquals(1, output.shape()[0]);
+        assertEquals(3, output.shape()[1]);
+    }
+
+}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/preprocessor/PoolingDataSetPreProcessorTest.java

@@ -1,164 +0,0 @@
-package org.deeplearning4j.rl4j.observation.preprocessor;
-
-import org.deeplearning4j.rl4j.observation.preprocessor.pooling.ObservationPool;
-import org.deeplearning4j.rl4j.observation.preprocessor.pooling.PoolContentAssembler;
-import org.junit.Assert;
-import org.junit.Test;
-import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.dataset.DataSet;
-import org.nd4j.linalg.factory.Nd4j;
-
-import static junit.framework.TestCase.assertTrue;
-import static org.junit.Assert.assertEquals;
-
-public class PoolingDataSetPreProcessorTest {
-
-    @Test(expected = NullPointerException.class)
-    public void when_dataSetIsNull_expect_NullPointerException() {
-        // Assemble
-        PoolingDataSetPreProcessor sut = PoolingDataSetPreProcessor.builder().build();
-
-        // Act
-        sut.preProcess(null);
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void when_dataSetHasMoreThanOneExample_expect_IllegalArgumentException() {
-        // Assemble
-        PoolingDataSetPreProcessor sut = PoolingDataSetPreProcessor.builder().build();
-
-        // Act
-        sut.preProcess(new DataSet(Nd4j.rand(new long[] { 2, 2, 2 }), null));
-    }
-
-    @Test
-    public void when_dataSetIsEmpty_expect_EmptyDataSet() {
-        // Assemble
-        PoolingDataSetPreProcessor sut = PoolingDataSetPreProcessor.builder().build();
-        DataSet ds = new DataSet(null, null);
-
-        // Act
-        sut.preProcess(ds);
-
-        // Assert
-        Assert.assertTrue(ds.isEmpty());
-    }
-
-    @Test
-    public void when_builderHasNoPoolOrAssembler_expect_defaultPoolBehavior() {
-        // Arrange
-        PoolingDataSetPreProcessor sut = PoolingDataSetPreProcessor.builder().build();
-        DataSet[] observations = new DataSet[5];
-        INDArray[] inputs = new INDArray[5];
-
-
-        // Act
-        for(int i = 0; i < 5; ++i) {
-            inputs[i] = Nd4j.rand(new long[] { 1, 2, 2 });
-            DataSet input = new DataSet(inputs[i], null);
-            sut.preProcess(input);
-            observations[i] = input;
-        }
-
-        // Assert
-        assertTrue(observations[0].isEmpty());
-        assertTrue(observations[1].isEmpty());
-        assertTrue(observations[2].isEmpty());
-
-        for(int i = 0; i < 4; ++i) {
-            assertEquals(inputs[i].getDouble(new int[] { 0, 0, 0 }), observations[3].getFeatures().getDouble(new int[] { 0, i, 0, 0 }), 0.0001);
-            assertEquals(inputs[i].getDouble(new int[] { 0, 0, 1 }), observations[3].getFeatures().getDouble(new int[] { 0, i, 0, 1 }), 0.0001);
-            assertEquals(inputs[i].getDouble(new int[] { 0, 1, 0 }), observations[3].getFeatures().getDouble(new int[] { 0, i, 1, 0 }), 0.0001);
-            assertEquals(inputs[i].getDouble(new int[] { 0, 1, 1 }), observations[3].getFeatures().getDouble(new int[] { 0, i, 1, 1 }), 0.0001);
-        }
-
-        for(int i = 0; i < 4; ++i) {
-            assertEquals(inputs[i+1].getDouble(new int[] { 0, 0, 0 }), observations[4].getFeatures().getDouble(new int[] { 0, i, 0, 0 }), 0.0001);
-            assertEquals(inputs[i+1].getDouble(new int[] { 0, 0, 1 }), observations[4].getFeatures().getDouble(new int[] { 0, i, 0, 1 }), 0.0001);
-            assertEquals(inputs[i+1].getDouble(new int[] { 0, 1, 0 }), observations[4].getFeatures().getDouble(new int[] { 0, i, 1, 0 }), 0.0001);
-            assertEquals(inputs[i+1].getDouble(new int[] { 0, 1, 1 }), observations[4].getFeatures().getDouble(new int[] { 0, i, 1, 1 }), 0.0001);
-        }
-
-    }
-
-    @Test
-    public void when_builderHasPoolAndAssembler_expect_paramPoolAndAssemblerAreUsed() {
-        // Arrange
-        INDArray input = Nd4j.rand(1, 1);
-        TestObservationPool pool = new TestObservationPool();
-        TestPoolContentAssembler assembler = new TestPoolContentAssembler();
-        PoolingDataSetPreProcessor sut = PoolingDataSetPreProcessor.builder()
-                .observablePool(pool)
-                .poolContentAssembler(assembler)
-                .build();
-
-        // Act
-        sut.preProcess(new DataSet(input, null));
-
-        // Assert
-        assertTrue(pool.isAtFullCapacityCalled);
-        assertTrue(pool.isGetCalled);
-        assertEquals(input.getDouble(0), pool.observation.getDouble(0), 0.0);
-        assertTrue(assembler.assembleIsCalled);
-    }
-
-    @Test
-    public void when_pastInputChanges_expect_outputNotChanged() {
-        // Arrange
-        INDArray input = Nd4j.zeros(1, 1);
-        TestObservationPool pool = new TestObservationPool();
-        TestPoolContentAssembler assembler = new TestPoolContentAssembler();
-        PoolingDataSetPreProcessor sut = PoolingDataSetPreProcessor.builder()
-                .observablePool(pool)
-                .poolContentAssembler(assembler)
-                .build();
-
-        // Act
-        sut.preProcess(new DataSet(input, null));
-        input.putScalar(0, 0, 1.0);
-
-        // Assert
-        assertEquals(0.0, pool.observation.getDouble(0), 0.0);
-    }
-
-    private static class TestObservationPool implements ObservationPool {
-
-        public INDArray observation;
-        public boolean isGetCalled;
-        public boolean isAtFullCapacityCalled;
-        private boolean isResetCalled;
-
-        @Override
-        public void add(INDArray observation) {
-            this.observation = observation;
-        }
-
-        @Override
-        public INDArray[] get() {
-            isGetCalled = true;
-            return new INDArray[0];
-        }
-
-        @Override
-        public boolean isAtFullCapacity() {
-            isAtFullCapacityCalled = true;
-            return true;
-        }
-
-        @Override
-        public void reset() {
-            isResetCalled = true;
-        }
-    }
-
-    private static class TestPoolContentAssembler implements PoolContentAssembler {
-
-        public boolean assembleIsCalled;
-
-        @Override
-        public INDArray assemble(INDArray[] poolContent) {
-            assembleIsCalled = true;
-            return Nd4j.create(1, 1);
-        }
-    }
-}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/preprocessor/SkippingDataSetPreProcessorTest.java

@@ -1,70 +0,0 @@
-package org.deeplearning4j.rl4j.observation.preprocessor;
-
-import org.junit.Test;
-import org.nd4j.linalg.dataset.DataSet;
-import org.nd4j.linalg.factory.Nd4j;
-
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-
-public class SkippingDataSetPreProcessorTest {
-    @Test(expected = IllegalArgumentException.class)
-    public void when_ctorSkipFrameIsZero_expect_IllegalArgumentException() {
-        SkippingDataSetPreProcessor sut = new SkippingDataSetPreProcessor(0);
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void when_builderSkipFrameIsZero_expect_IllegalArgumentException() {
-        SkippingDataSetPreProcessor sut = SkippingDataSetPreProcessor.builder()
-                .skipFrame(0)
-                .build();
-    }
-
-    @Test
-    public void when_skipFrameIs3_expect_Skip2OutOf3() {
-        // Arrange
-        SkippingDataSetPreProcessor sut = SkippingDataSetPreProcessor.builder()
-                .skipFrame(3)
-                .build();
-        DataSet[] results = new DataSet[4];
-
-        // Act
-        for(int i = 0; i < 4; ++i) {
-            results[i] = new DataSet(Nd4j.create(new double[] { 123.0 }), null);
-            sut.preProcess(results[i]);
-        }
-
-        // Assert
-        assertFalse(results[0].isEmpty());
-        assertTrue(results[1].isEmpty());
-        assertTrue(results[2].isEmpty());
-        assertFalse(results[3].isEmpty());
-    }
-
-    @Test
-    public void when_resetIsCalled_expect_skippingIsReset() {
-        // Arrange
-        SkippingDataSetPreProcessor sut = SkippingDataSetPreProcessor.builder()
-                .skipFrame(3)
-                .build();
-        DataSet[] results = new DataSet[4];
-
-        // Act
-        results[0] = new DataSet(Nd4j.create(new double[] { 123.0 }), null);
-        results[1] = new DataSet(Nd4j.create(new double[] { 123.0 }), null);
-        results[2] = new DataSet(Nd4j.create(new double[] { 123.0 }), null);
-        results[3] = new DataSet(Nd4j.create(new double[] { 123.0 }), null);
-
-        sut.preProcess(results[0]);
-        sut.preProcess(results[1]);
-        sut.reset();
-        sut.preProcess(results[2]);
-        sut.preProcess(results[3]);
-
-        // Assert
-        assertFalse(results[0].isEmpty());
-        assertTrue(results[1].isEmpty());
-        assertFalse(results[2].isEmpty());
-        assertTrue(results[3].isEmpty());
-    }
-}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/preprocessor/pooling/ChannelStackPoolContentAssemblerTest.java

@@ -1,41 +0,0 @@
-package org.deeplearning4j.rl4j.observation.preprocessor.pooling;
-
-import org.junit.Test;
-import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.factory.Nd4j;
-
-import static org.junit.Assert.assertEquals;
-
-public class ChannelStackPoolContentAssemblerTest {
-
-    @Test
-    public void when_assemble_expect_poolContentStackedOnChannel() {
-        // Assemble
-        ChannelStackPoolContentAssembler sut = new ChannelStackPoolContentAssembler();
-        INDArray[] poolContent = new INDArray[] {
-            Nd4j.rand(2, 2),
-            Nd4j.rand(2, 2),
-        };
-
-        // Act
-        INDArray result = sut.assemble(poolContent);
-
-        // Assert
-        assertEquals(3, result.shape().length);
-        assertEquals(2, result.shape()[0]);
-        assertEquals(2, result.shape()[1]);
-        assertEquals(2, result.shape()[2]);
-
-        assertEquals(poolContent[0].getDouble(0, 0), result.getDouble(0, 0, 0), 0.0001);
-        assertEquals(poolContent[0].getDouble(0, 1), result.getDouble(0, 0, 1), 0.0001);
-        assertEquals(poolContent[0].getDouble(1, 0), result.getDouble(0, 1, 0), 0.0001);
-        assertEquals(poolContent[0].getDouble(1, 1), result.getDouble(0, 1, 1), 0.0001);
-
-        assertEquals(poolContent[1].getDouble(0, 0), result.getDouble(1, 0, 0), 0.0001);
-        assertEquals(poolContent[1].getDouble(0, 1), result.getDouble(1, 0, 1), 0.0001);
-        assertEquals(poolContent[1].getDouble(1, 0), result.getDouble(1, 1, 0), 0.0001);
-        assertEquals(poolContent[1].getDouble(1, 1), result.getDouble(1, 1, 1), 0.0001);
-
-    }
-
-}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/preprocessor/pooling/CircularFifoObservationPoolTest.java

@@ -1,100 +0,0 @@
-package org.deeplearning4j.rl4j.observation.preprocessor.pooling;
-
-import org.junit.Test;
-import org.nd4j.linalg.api.ndarray.INDArray;
-import org.nd4j.linalg.factory.Nd4j;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-
-public class CircularFifoObservationPoolTest {
-
-    @Test(expected = IllegalArgumentException.class)
-    public void when_poolSizeZeroOrLess_expect_IllegalArgumentException() {
-        CircularFifoObservationPool sut = new CircularFifoObservationPool(0);
-    }
-
-    @Test
-    public void when_poolIsEmpty_expect_NotReady() {
-        // Assemble
-        CircularFifoObservationPool sut = new CircularFifoObservationPool();
-
-        // Act
-        boolean isReady = sut.isAtFullCapacity();
-
-        // Assert
-        assertFalse(isReady);
-    }
-
-    @Test
-    public void when_notEnoughElementsInPool_expect_notReady() {
-        // Assemble
-        CircularFifoObservationPool sut = new CircularFifoObservationPool();
-        sut.add(Nd4j.create(new double[] { 123.0 }));
-
-        // Act
-        boolean isReady = sut.isAtFullCapacity();
-
-        // Assert
-        assertFalse(isReady);
-    }
-
-    @Test
-    public void when_enoughElementsInPool_expect_ready() {
-        // Assemble
-        CircularFifoObservationPool sut = CircularFifoObservationPool.builder()
-                .poolSize(2)
-                .build();
-        sut.add(Nd4j.createFromArray(123.0));
-        sut.add(Nd4j.createFromArray(123.0));
-
-        // Act
-        boolean isReady = sut.isAtFullCapacity();
-
-        // Assert
-        assertTrue(isReady);
-    }
-
-    @Test
-    public void when_addMoreThanSize_expect_getReturnOnlyLastElements() {
-        // Assemble
-        CircularFifoObservationPool sut = CircularFifoObservationPool.builder().build();
-        sut.add(Nd4j.createFromArray(0.0));
-        sut.add(Nd4j.createFromArray(1.0));
-        sut.add(Nd4j.createFromArray(2.0));
-        sut.add(Nd4j.createFromArray(3.0));
-        sut.add(Nd4j.createFromArray(4.0));
-        sut.add(Nd4j.createFromArray(5.0));
-        sut.add(Nd4j.createFromArray(6.0));
-
-        // Act
-        INDArray[] result = sut.get();
-
-        // Assert
-        assertEquals(3.0, result[0].getDouble(0), 0.0);
-        assertEquals(4.0, result[1].getDouble(0), 0.0);
-        assertEquals(5.0, result[2].getDouble(0), 0.0);
-        assertEquals(6.0, result[3].getDouble(0), 0.0);
-    }
-
-    @Test
-    public void when_resetIsCalled_expect_poolContentFlushed() {
-        // Assemble
-        CircularFifoObservationPool sut = CircularFifoObservationPool.builder().build();
-        sut.add(Nd4j.createFromArray(0.0));
-        sut.add(Nd4j.createFromArray(1.0));
-        sut.add(Nd4j.createFromArray(2.0));
-        sut.add(Nd4j.createFromArray(3.0));
-        sut.add(Nd4j.createFromArray(4.0));
-        sut.add(Nd4j.createFromArray(5.0));
-        sut.add(Nd4j.createFromArray(6.0));
-        sut.reset();
-
-        // Act
-        INDArray[] result = sut.get();
-
-        // Assert
-        assertEquals(0, result.length);
-    }
-}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/transform/operation/HistoryMergeTransformTest.java

@@ -0,0 +1,166 @@
+package org.deeplearning4j.rl4j.observation.transform.operation;
+
+import org.deeplearning4j.rl4j.observation.transform.operation.historymerge.HistoryMergeAssembler;
+import org.deeplearning4j.rl4j.observation.transform.operation.historymerge.HistoryMergeElementStore;
+import org.junit.Test;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import static org.junit.Assert.*;
+
+public class HistoryMergeTransformTest {
+
+    @Test
+    public void when_firstDimensionIsNotBatch_expect_observationAddedAsIs() {
+        // Arrange
+        MockStore store = new MockStore(false);
+        HistoryMergeTransform sut = HistoryMergeTransform.builder()
+                .isFirstDimenstionBatch(false)
+                .elementStore(store)
+                .build();
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+
+        // Act
+        sut.transform(input);
+
+        // Assert
+        assertEquals(1, store.addedObservation.shape().length);
+        assertEquals(3, store.addedObservation.shape()[0]);
+    }
+
+    @Test
+    public void when_firstDimensionIsBatch_expect_observationAddedAsSliced() {
+        // Arrange
+        MockStore store = new MockStore(false);
+        HistoryMergeTransform sut = HistoryMergeTransform.builder()
+                .isFirstDimenstionBatch(true)
+                .elementStore(store)
+                .build();
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0 }).reshape(1, 3);
+
+        // Act
+        sut.transform(input);
+
+        // Assert
+        assertEquals(1, store.addedObservation.shape().length);
+        assertEquals(3, store.addedObservation.shape()[0]);
+    }
+
+    @Test
+    public void when_notReady_expect_resultIsNull() {
+        // Arrange
+        MockStore store = new MockStore(false);
+        HistoryMergeTransform sut = HistoryMergeTransform.builder()
+                .isFirstDimenstionBatch(true)
+                .elementStore(store)
+                .build();
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+
+        // Act
+        INDArray result = sut.transform(input);
+
+        // Assert
+        assertNull(result);
+    }
+
+    @Test
+    public void when_notShouldStoreCopy_expect_sameIsStored() {
+        // Arrange
+        MockStore store = new MockStore(false);
+        HistoryMergeTransform sut = HistoryMergeTransform.builder()
+                .shouldStoreCopy(false)
+                .elementStore(store)
+                .build();
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+
+        // Act
+        INDArray result = sut.transform(input);
+
+        // Assert
+        assertSame(input, store.addedObservation);
+    }
+
+    @Test
+    public void when_shouldStoreCopy_expect_copyIsStored() {
+        // Arrange
+        MockStore store = new MockStore(true);
+        HistoryMergeTransform sut = HistoryMergeTransform.builder()
+                .shouldStoreCopy(true)
+                .elementStore(store)
+                .build();
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+
+        // Act
+        INDArray result = sut.transform(input);
+
+        // Assert
+        assertNotSame(input, store.addedObservation);
+        assertEquals(1, store.addedObservation.shape().length);
+        assertEquals(3, store.addedObservation.shape()[0]);
+    }
+
+    @Test
+    public void when_transformCalled_expect_storeContentAssembledAndOutputHasCorrectShape() {
+        // Arrange
+        MockStore store = new MockStore(true);
+        MockAssemble assemble = new MockAssemble();
+        HistoryMergeTransform sut = HistoryMergeTransform.builder()
+                .elementStore(store)
+                .assembler(assemble)
+                .build();
+        INDArray input = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+
+        // Act
+        INDArray result = sut.transform(input);
+
+        // Assert
+        assertEquals(1, assemble.assembleElements.length);
+        assertSame(store.addedObservation, assemble.assembleElements[0]);
+
+        assertEquals(2, result.shape().length);
+        assertEquals(1, result.shape()[0]);
+        assertEquals(3, result.shape()[1]);
+    }
+
+    public static class MockStore implements HistoryMergeElementStore {
+
+        private final boolean isReady;
+        private INDArray addedObservation;
+
+        public MockStore(boolean isReady) {
+
+            this.isReady = isReady;
+        }
+
+        @Override
+        public void add(INDArray observation) {
+            addedObservation = observation;
+        }
+
+        @Override
+        public INDArray[] get() {
+            return new INDArray[] { addedObservation };
+        }
+
+        @Override
+        public boolean isReady() {
+            return isReady;
+        }
+
+        @Override
+        public void reset() {
+
+        }
+    }
+
+    public static class MockAssemble implements HistoryMergeAssembler {
+
+        private INDArray[] assembleElements;
+
+        @Override
+        public INDArray assemble(INDArray[] elements) {
+            assembleElements = elements;
+            return elements[0];
+        }
+    }
+}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/transform/operation/historymerge/CircularFifoStoreTest.java

@@ -0,0 +1,77 @@
+package org.deeplearning4j.rl4j.observation.transform.operation.historymerge;
+
+import org.junit.Test;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import static org.junit.Assert.*;
+
+public class CircularFifoStoreTest {
+
+    @Test(expected = IllegalArgumentException.class)
+    public void when_fifoSizeIsLessThan1_expect_exception() {
+        // Arrange
+        CircularFifoStore sut = new CircularFifoStore(0);
+    }
+
+    @Test
+    public void when_adding2elementsWithSize2_expect_notReadyAfter1stReadyAfter2nd() {
+        // Arrange
+        CircularFifoStore sut = new CircularFifoStore(2);
+        INDArray firstElement = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+        INDArray secondElement = Nd4j.create(new double[] { 10.0, 20.0, 30.0 });
+
+        // Act
+        sut.add(firstElement);
+        boolean isReadyAfter1st = sut.isReady();
+        sut.add(secondElement);
+        boolean isReadyAfter2nd = sut.isReady();
+
+        // Assert
+        assertFalse(isReadyAfter1st);
+        assertTrue(isReadyAfter2nd);
+    }
+
+    @Test
+    public void when_adding2elementsWithSize2_expect_getReturnThese2() {
+        // Arrange
+        CircularFifoStore sut = new CircularFifoStore(2);
+        INDArray firstElement = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+        INDArray secondElement = Nd4j.create(new double[] { 10.0, 20.0, 30.0 });
+
+        // Act
+        sut.add(firstElement);
+        sut.add(secondElement);
+        INDArray[] results = sut.get();
+
+        // Assert
+        assertEquals(2, results.length);
+
+        assertEquals(1.0, results[0].getDouble(0), 0.00001);
+        assertEquals(2.0, results[0].getDouble(1), 0.00001);
+        assertEquals(3.0, results[0].getDouble(2), 0.00001);
+
+        assertEquals(10.0, results[1].getDouble(0), 0.00001);
+        assertEquals(20.0, results[1].getDouble(1), 0.00001);
+        assertEquals(30.0, results[1].getDouble(2), 0.00001);
+
+    }
+
+    @Test
+    public void when_adding2elementsThenCallingReset_expect_getReturnEmpty() {
+        // Arrange
+        CircularFifoStore sut = new CircularFifoStore(2);
+        INDArray firstElement = Nd4j.create(new double[] { 1.0, 2.0, 3.0 });
+        INDArray secondElement = Nd4j.create(new double[] { 10.0, 20.0, 30.0 });
+
+        // Act
+        sut.add(firstElement);
+        sut.add(secondElement);
+        sut.reset();
+        INDArray[] results = sut.get();
+
+        // Assert
+        assertEquals(0, results.length);
+    }
+
+}

rl4j/rl4j-core/src/test/java/org/deeplearning4j/rl4j/observation/transform/operation/historymerge/HistoryStackAssemblerTest.java

@@ -0,0 +1,37 @@
+package org.deeplearning4j.rl4j.observation.transform.operation.historymerge;
+
+import org.junit.Test;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.factory.Nd4j;
+
+import static org.junit.Assert.*;
+
+public class HistoryStackAssemblerTest {
+
+    @Test
+    public void when_assembling2INDArrays_expect_stackedAsResult() {
+        // Arrange
+        INDArray[] input = new INDArray[] {
+                Nd4j.create(new double[] { 1.0, 2.0, 3.0 }),
+                Nd4j.create(new double[] { 10.0, 20.0, 30.0 }),
+        };
+        HistoryStackAssembler sut = new HistoryStackAssembler();
+
+        // Act
+        INDArray result = sut.assemble(input);
+
+        // Assert
+        assertEquals(2, result.shape().length);
+        assertEquals(2, result.shape()[0]);
+        assertEquals(3, result.shape()[1]);
+
+        assertEquals(1.0, result.getDouble(0, 0), 0.00001);
+        assertEquals(2.0, result.getDouble(0, 1), 0.00001);
+        assertEquals(3.0, result.getDouble(0, 2), 0.00001);
+
+        assertEquals(10.0, result.getDouble(1, 0), 0.00001);
+        assertEquals(20.0, result.getDouble(1, 1), 0.00001);
+        assertEquals(30.0, result.getDouble(1, 2), 0.00001);
+
+    }
+}