Added testing and returning staked observation flat.

Author: cmard

com.unity.ml-agents/Runtime/Agent.cs

@@ -1190,7 +1190,7 @@ public ReadOnlyCollection<float> GetObservations()
         /// <see cref="Heuristic(in ActionBuffers)"/> method to avoid recomputing the observations.
         /// </summary>
         /// <returns>A read-only view of the stacked observations list.</returns>
-        public ReadOnlyCollection<ReadOnlyCollection<float>> GetStackedObservations()
+        public ReadOnlyCollection<float> GetStackedObservations()
         {
             return stackedCollectObservationsSensor.GetStackedObservations();
         }

com.unity.ml-agents/Runtime/Sensors/StackingSensor.cs

@@ -36,6 +36,11 @@ public class StackingSensor : ISensor, IBuiltInSensor
         /// Buffer of previous observations
         /// </summary>
         float[][] m_StackedObservations;
+        //[
+        //[1,2]
+        //[3,4]
+        //[5,6]
+        //]
 
         byte[][] m_StackedCompressedObservations;
 
@@ -286,15 +291,15 @@ public BuiltInSensorType GetBuiltInSensorType()
         /// Returns a read-only view of the observations that added.
         /// </summary>
         /// <returns>A read-only view of the observations list.</returns>
-        internal ReadOnlyCollection<ReadOnlyCollection<float>> GetStackedObservations()
+        internal ReadOnlyCollection<float> GetStackedObservations()
         {
-            List<ReadOnlyCollection<float>> layer = new List<ReadOnlyCollection<float>>();
-            foreach (float[] l in m_StackedObservations)
+            List<float> observations = new List<float>();
+            for (var i = 0; i < m_NumStackedObservations; i++)
             {
-                layer.Add(l.ToList().AsReadOnly());
+                var obsIndex = (m_CurrentIndex + 1 + i) % m_NumStackedObservations;
+                observations.AddRange(m_StackedObservations[obsIndex].ToList());
             }
-
-            return layer.AsReadOnly();
+            return observations.AsReadOnly();
         }
     }
 }

com.unity.ml-agents/Tests/Runtime/Sensor/StackingSensorTests.cs

@@ -76,29 +76,41 @@ public void AssertStackingReset()
         public void TestVectorStacking()
         {
             VectorSensor wrapped = new VectorSensor(2);
-            ISensor sensor = new StackingSensor(wrapped, 3);
+            StackingSensor sensor = new StackingSensor(wrapped, 3);
 
             wrapped.AddObservation(new[] { 1f, 2f });
             SensorTestHelper.CompareObservation(sensor, new[] { 0f, 0f, 0f, 0f, 1f, 2f });
+            var data = sensor.GetStackedObservations();
+            Assert.IsTrue(data.ToArray().SequenceEqual(new[] { 0f, 0f, 0f, 0f, 1f, 2f }));
 
             sensor.Update();
             wrapped.AddObservation(new[] { 3f, 4f });
             SensorTestHelper.CompareObservation(sensor, new[] { 0f, 0f, 1f, 2f, 3f, 4f });
+            data = sensor.GetStackedObservations();
+            Assert.IsTrue(data.ToArray().SequenceEqual(new[] { 0f, 0f, 1f, 2f, 3f, 4f }));
 
             sensor.Update();
             wrapped.AddObservation(new[] { 5f, 6f });
             SensorTestHelper.CompareObservation(sensor, new[] { 1f, 2f, 3f, 4f, 5f, 6f });
+            data = sensor.GetStackedObservations();
+            Assert.IsTrue(data.ToArray().SequenceEqual(new[] { 1f, 2f, 3f, 4f, 5f, 6f }));
 
             sensor.Update();
             wrapped.AddObservation(new[] { 7f, 8f });
             SensorTestHelper.CompareObservation(sensor, new[] { 3f, 4f, 5f, 6f, 7f, 8f });
+            data = sensor.GetStackedObservations();
+            Assert.IsTrue(data.ToArray().SequenceEqual(new[] { 3f, 4f, 5f, 6f, 7f, 8f }));
 
             sensor.Update();
             wrapped.AddObservation(new[] { 9f, 10f });
             SensorTestHelper.CompareObservation(sensor, new[] { 5f, 6f, 7f, 8f, 9f, 10f });
+            data = sensor.GetStackedObservations();
+            Assert.IsTrue(data.ToArray().SequenceEqual(new[] { 5f, 6f, 7f, 8f, 9f, 10f }));
 
             // Check that if we don't call Update(), the same observations are produced
             SensorTestHelper.CompareObservation(sensor, new[] { 5f, 6f, 7f, 8f, 9f, 10f });
+            data = sensor.GetStackedObservations();
+            Assert.IsTrue(data.ToArray().SequenceEqual(new[] { 5f, 6f, 7f, 8f, 9f, 10f }));
         }
 
         [Test]