/// <summary>
/// Calcualte the loss and initial gradients.
/// </summary>
/// <param name="sender">Specifies the MemoryLoss layer firing the event.</param>
/// <param name="e">Specifies the arguments with the Bottom(s) flowing into the MemoryLoss layer and the loss value to be filled out.</param>
/// <remarks>
/// The initial gradient is calculated such that it encourages the action that was taken to be taken.
///
/// When using a Sigmoid, the gradient = (action=0) ? 1 - Aprob : 0 - Aprob.
/// When using a Softmax, the gradient = the SoftmaxCrossEntropyLoss backward.
///
/// @see [CS231n Convolution Neural Networks for Visual Recognition](http://cs231n.github.io/neural-networks-2/#losses) by Karpathy, Stanford University
///
/// Regardless of the gradient used, the gradient is then modulated by multiplying it with the discounted rewards.
/// </remarks>
private void memLoss_OnGetLoss(object sender, MemoryLossLayerGetLossArgs <T> e)
{
if (m_bSkipLoss)
{
return;
}
int nCount = m_blobPolicyGradient.count();
long hActionOneHot = m_blobActionOneHot.gpu_data;
long hPolicyGrad = m_blobPolicyGradient.mutable_gpu_data;
long hDiscountedR = m_blobDiscountedR.gpu_data;
double dfLoss;
Blob <T> blobOriginalBottom = e.Bottom[0];
int nDataSize = e.Bottom[0].count(1);
bool bUsingEndData = false;
// When using a recurrent model and receiving data with more than one sequence,
// copy and only use the last sequence data.
if (m_nRecurrentSequenceLength > 1)
{
if (e.Bottom[0].num > 1)
{
m_blobAprobLogit.CopyFrom(e.Bottom[0], false, true);
m_blobAprobLogit.CopyFrom(e.Bottom[0], true);
List <int> rgShape = e.Bottom[0].shape();
rgShape[0] = 1;
e.Bottom[0].Reshape(rgShape);
e.Bottom[0].CopyFrom(m_blobAprobLogit, (m_blobAprobLogit.num - 1) * nDataSize, 0, nDataSize, true, true);
bUsingEndData = true;
}
}
long hBottomDiff = e.Bottom[0].mutable_gpu_diff;
// Calculate the initial gradients (policy grad initially just contains the action probabilities)
if (m_softmax != null)
{
BlobCollection <T> colBottom = new BlobCollection <T>();
BlobCollection <T> colTop = new BlobCollection <T>();
colBottom.Add(e.Bottom[0]); // aprob logit
colBottom.Add(m_blobActionOneHot); // action one-hot vectors
colTop.Add(m_blobLoss);
colTop.Add(m_blobPolicyGradient);
if (!m_bSoftmaxCeSetup)
{
m_softmaxCe.Setup(colBottom, colTop);
m_bSoftmaxCeSetup = true;
}
dfLoss = m_softmaxCe.Forward(colBottom, colTop);
m_softmaxCe.Backward(colTop, new List <bool>()
{
true, false
}, colBottom);
hPolicyGrad = colBottom[0].gpu_diff;
}
else
{
// Calculate (a=0) ? 1-aprob : 0-aprob
m_mycaffe.Cuda.add_scalar(nCount, -1.0, hActionOneHot); // invert one hot
m_mycaffe.Cuda.abs(nCount, hActionOneHot, hActionOneHot);
m_mycaffe.Cuda.mul_scalar(nCount, -1.0, hPolicyGrad); // negate Aprob
m_mycaffe.Cuda.add(nCount, hActionOneHot, hPolicyGrad, hPolicyGrad); // gradient = ((a=0)?1:0) - Aprob
dfLoss = Utility.ConvertVal <T>(m_blobPolicyGradient.sumsq_data());
m_mycaffe.Cuda.mul_scalar(nCount, -1.0, hPolicyGrad); // invert for we ApplyUpdate subtracts the gradients
}
// Modulate the gradient with the advantage (PG magic happens right here.)
m_mycaffe.Cuda.mul(nCount, hPolicyGrad, hDiscountedR, hPolicyGrad);
e.Loss = dfLoss;
e.EnableLossUpdate = false; // apply gradients to bottom directly.
if (hPolicyGrad != hBottomDiff)
{
m_mycaffe.Cuda.copy(nCount, hPolicyGrad, hBottomDiff);
}
// When using recurrent model with more than one sequence of data, only
// copy the diff to the last in the sequence and zero out the rest in the sequence.
if (m_nRecurrentSequenceLength > 1 && bUsingEndData)
{
m_blobAprobLogit.SetDiff(0);
m_blobAprobLogit.CopyFrom(e.Bottom[0], 0, (m_blobAprobLogit.num - 1) * nDataSize, nDataSize, false, true);
e.Bottom[0].CopyFrom(m_blobAprobLogit, false, true);
e.Bottom[0].CopyFrom(m_blobAprobLogit, true);
}
}
/// <summary>
/// Calcualte the loss and initial gradients.
/// </summary>
/// <param name="sender">Specifies the MemoryLoss layer firing the event.</param>
/// <param name="e">Specifies the arguments with the Bottom(s) flowing into the MemoryLoss layer and the loss value to be filled out.</param>
/// <remarks>
/// The initial gradient is calculated such that it encourages the action that was taken to be taken.
///
/// When using a Sigmoid, the gradient = (action=0) ? 1 - Aprob : 0 - Aprob.
/// When using a Softmax, the gradient = the SoftmaxCrossEntropyLoss backward.
///
/// @see [CS231n Convolution Neural Networks for Visual Recognition](http://cs231n.github.io/neural-networks-2/#losses) by Karpathy, Stanford University
///
/// Regardless of the gradient used, the gradient is then modulated by multiplying it with the discounted rewards.
/// </remarks>
private void memLoss_OnGetLoss(object sender, MemoryLossLayerGetLossArgs <T> e)
{
if (m_bSkipLoss)
{
return;
}
int nCount = m_blobPolicyGradient.count();
long hActionOneHot = m_blobActionOneHot.gpu_data;
long hPolicyGrad = m_blobPolicyGradient.mutable_gpu_data;
long hBottomDiff = e.Bottom[0].mutable_gpu_diff;
long hDiscountedR = m_blobDiscountedR.gpu_data;
double dfLoss;
// Calculate the initial gradients (policy grad initially just contains the action probabilities)
if (m_softmax != null)
{
BlobCollection <T> colBottom = new BlobCollection <T>();
BlobCollection <T> colTop = new BlobCollection <T>();
colBottom.Add(e.Bottom[0]); // aprob logit
colBottom.Add(m_blobActionOneHot); // action one-hot vectors
colTop.Add(m_blobLoss);
colTop.Add(m_blobPolicyGradient);
if (!m_bSoftmaxCeSetup)
{
m_softmaxCe.Setup(colBottom, colTop);
m_bSoftmaxCeSetup = true;
}
dfLoss = m_softmaxCe.Forward(colBottom, colTop);
m_softmaxCe.Backward(colTop, new List <bool>()
{
true, false
}, colBottom);
hPolicyGrad = colBottom[0].gpu_diff;
}
else
{
// Calculate (a=0) ? 1-aprob : 0-aprob
m_mycaffe.Cuda.add_scalar(nCount, -1.0, hActionOneHot); // invert one hot
m_mycaffe.Cuda.abs(nCount, hActionOneHot, hActionOneHot);
m_mycaffe.Cuda.mul_scalar(nCount, -1.0, hPolicyGrad); // negate Aprob
m_mycaffe.Cuda.add(nCount, hActionOneHot, hPolicyGrad, hPolicyGrad); // gradient = ((a=0)?1:0) - Aprob
dfLoss = Utility.ConvertVal <T>(m_blobPolicyGradient.sumsq_data());
m_mycaffe.Cuda.mul_scalar(nCount, -1.0, hPolicyGrad); // invert for we ApplyUpdate subtracts the gradients
}
// Modulate the gradient with the advantage (PG magic happens right here.)
m_mycaffe.Cuda.mul(nCount, hPolicyGrad, hDiscountedR, hPolicyGrad);
e.Loss = dfLoss;
e.EnableLossUpdate = false; // apply gradients to bottom directly.
if (hPolicyGrad != hBottomDiff)
{
m_mycaffe.Cuda.copy(nCount, hPolicyGrad, hBottomDiff);
}
}