Method to return stacked observations

Author: cmard

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

@@ -320,6 +320,11 @@ internal struct AgentParameters
         /// </summary>
         internal VectorSensor collectObservationsSensor;
 
+        /// <summary>
+        /// StackingSensor which is written to by AddVectorObs
+        /// </summary>
+        internal StackingSensor stackedCollectObservationsSensor;
+
         private RecursionChecker m_CollectObservationsChecker = new RecursionChecker("CollectObservations");
         private RecursionChecker m_OnEpisodeBeginChecker = new RecursionChecker("OnEpisodeBegin");
 
@@ -981,9 +986,9 @@ internal void InitializeSensors()
                 collectObservationsSensor = new VectorSensor(param.VectorObservationSize);
                 if (param.NumStackedVectorObservations > 1)
                 {
-                    var stackingSensor = new StackingSensor(
+                    stackedCollectObservationsSensor = new StackingSensor(
                         collectObservationsSensor, param.NumStackedVectorObservations);
-                    sensors.Add(stackingSensor);
+                    sensors.Add(stackedCollectObservationsSensor);
                 }
                 else
                 {
@@ -1179,6 +1184,17 @@ public ReadOnlyCollection<float> GetObservations()
             return collectObservationsSensor.GetObservations();
         }
 
+        /// <summary>
+        /// Returns a read-only view of the stacked observations that were generated in
+        /// <see cref="CollectObservations(VectorSensor)"/>. This is mainly useful inside of a
+        /// <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()
+        {
+            return stackedCollectObservationsSensor.GetStackedObservations();
+        }
+
         /// <summary>
         /// Implement `WriteDiscreteActionMask()` to collects the masks for discrete
         /// actions. When using discrete actions, the agent will not perform the masked

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

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using UnityEngine;
 using Unity.Barracuda;
@@ -279,5 +281,20 @@ public BuiltInSensorType GetBuiltInSensorType()
             IBuiltInSensor wrappedBuiltInSensor = m_WrappedSensor as IBuiltInSensor;
             return wrappedBuiltInSensor?.GetBuiltInSensorType() ?? BuiltInSensorType.Unknown;
         }
+
+        /// <summary>
+        /// 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()
+        {
+            List<ReadOnlyCollection<float>> layer = new List<ReadOnlyCollection<float>>();
+            foreach (float[] l in m_StackedObservations)
+            {
+                layer.Add(l.ToList().AsReadOnly());
+            }
+
+            return layer.AsReadOnly();
+        }
     }
 }