Unity 机器学习代理工具包 (ML-Agents) 是一个开源项目,它使游戏和模拟能够作为训练智能代理的环境。
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using System;
namespace Unity.MLAgents.Sensors
{
/// <summary>
/// Sensor that wraps around another Sensor to provide temporal stacking.
/// Conceptually, consecutive observations are stored left-to-right, which is how they're output
/// For example, 4 stacked sets of observations would be output like
/// | t = now - 3 | t = now -3 | t = now - 2 | t = now |
/// Internally, a circular buffer of arrays is used. The m_CurrentIndex represents the most recent observation.
///
/// Currently, compressed and multidimensional observations are not supported.
/// </summary>
public class StackingSensor : ISensor
{
/// <summary>
/// The wrapped sensor.
/// </summary>
ISensor m_WrappedSensor;
/// <summary>
/// Number of stacks to save
/// </summary>
int m_NumStackedObservations;
int m_UnstackedObservationSize;
string m_Name;
int[] m_Shape;
/// <summary>
/// Buffer of previous observations
/// </summary>
float[][] m_StackedObservations;
int m_CurrentIndex;
ObservationWriter m_LocalWriter = new ObservationWriter();
/// <summary>
/// Initializes the sensor.
/// </summary>
/// <param name="wrapped">The wrapped sensor.</param>
/// <param name="numStackedObservations">Number of stacked observations to keep.</param>
public StackingSensor(ISensor wrapped, int numStackedObservations)
{
// TODO ensure numStackedObservations > 1
m_WrappedSensor = wrapped;
m_NumStackedObservations = numStackedObservations;
m_Name = $"StackingSensor_size{numStackedObservations}_{wrapped.GetName()}";
if (wrapped.GetCompressionType() != SensorCompressionType.None)
{
throw new UnityAgentsException("StackingSensor doesn't support compressed observations.'");
}
var shape = wrapped.GetObservationShape();
if (shape.Length != 1)
{
throw new UnityAgentsException("Only 1-D observations are supported by StackingSensor");
}
m_Shape = new int[shape.Length];
m_UnstackedObservationSize = wrapped.ObservationSize();
for (int d = 0; d < shape.Length; d++)
{
m_Shape[d] = shape[d];
}
// TODO support arbitrary stacking dimension
m_Shape[0] *= numStackedObservations;
m_StackedObservations = new float[numStackedObservations][];
for (var i = 0; i < numStackedObservations; i++)
{
m_StackedObservations[i] = new float[m_UnstackedObservationSize];
}
}
/// <inheritdoc/>
public int Write(ObservationWriter writer)
{
// First, call the wrapped sensor's write method. Make sure to use our own writer, not the passed one.
var wrappedShape = m_WrappedSensor.GetObservationShape();
m_LocalWriter.SetTarget(m_StackedObservations[m_CurrentIndex], wrappedShape, 0);
m_WrappedSensor.Write(m_LocalWriter);
// Now write the saved observations (oldest first)
var numWritten = 0;
for (var i = 0; i < m_NumStackedObservations; i++)
{
var obsIndex = (m_CurrentIndex + 1 + i) % m_NumStackedObservations;
writer.AddRange(m_StackedObservations[obsIndex], numWritten);
numWritten += m_UnstackedObservationSize;
}
return numWritten;
}
/// <summary>
/// Updates the index of the "current" buffer.
/// </summary>
public void Update()
{
m_WrappedSensor.Update();
m_CurrentIndex = (m_CurrentIndex + 1) % m_NumStackedObservations;
}
/// <inheritdoc/>
public void Reset()
{
m_WrappedSensor.Reset();
// Zero out the buffer.
for (var i = 0; i < m_NumStackedObservations; i++)
{
Array.Clear(m_StackedObservations[i], 0, m_StackedObservations[i].Length);
}
}
/// <inheritdoc/>
public int[] GetObservationShape()
{
return m_Shape;
}
/// <inheritdoc/>
public string GetName()
{
return m_Name;
}
/// <inheritdoc/>
public virtual byte[] GetCompressedObservation()
{
return null;
}
/// <inheritdoc/>
public virtual SensorCompressionType GetCompressionType()
{
return SensorCompressionType.None;
}
/// <inheritdoc/>
public SensorType GetSensorType()
{
return SensorType.Observation;
}
// TODO support stacked compressed observations (byte stream)
}
}