public override void Concat(Volume <float> right, Volume <float> result)
{
var batchSize = Math.Max(this.Shape.Dimensions[3], right.Shape.Dimensions[3]);
if (this.Shape.TotalLength > 1 && right.Shape.TotalLength > 1)
{
var left = ReShape(new Shape(1, 1, -1, batchSize));
right = right.ReShape(new Shape(1, 1, -1, batchSize));
var elementPerBatch = result.Shape.TotalLength / batchSize;
var threshold = left.Shape.Dimensions[2];
for (var n = 0; n < batchSize; n++)
{
for (var i = 0; i < elementPerBatch; i++)
{
result.Set(0, 0, i, n, i < threshold ? left.Get(0, 0, i, n) : right.Get(0, 0, i - threshold, n));
}
}
}
else if (this.Shape.TotalLength == 1 && right.Shape.TotalLength > 1)
{
// Left volume is actually a scalar => broadcast its value
right = right.ReShape(new Shape(1, 1, -1, batchSize));
var elementPerBatch = result.Shape.TotalLength / batchSize;
var threshold = 1;
for (var n = 0; n < batchSize; n++)
{
for (var i = 0; i < elementPerBatch; i++)
{
result.Set(0, 0, i, n, i < threshold ? Get(0) : right.Get(0, 0, i - threshold, n));
}
}
}
else
{
// Right volume is actually a scalar => broadcast its value
var left = ReShape(new Shape(1, 1, -1, batchSize));
var elementPerBatch = result.Shape.TotalLength / batchSize;
var threshold = left.Shape.Dimensions[2];
for (var n = 0; n < batchSize; n++)
{
for (var i = 0; i < elementPerBatch; i++)
{
result.Set(0, 0, i, n, i < threshold ? left.Get(0, 0, i, n) : right.Get(0));
}
}
}
}
public override void SoftmaxGradient(Volume <float> outputGradient, Volume <float> inputGradient)
{
var batchSize = this.Shape.Dimensions[3];
var outputReshape = ReShape(-1, batchSize);
var outputGradientReshape = outputGradient.ReShape(-1, batchSize);
var inputGradientReshape = inputGradient.ReShape(-1, batchSize);
var firstDim = outputReshape.Shape.Dimensions[0];
for (var b = 0; b < batchSize; b++)
{
var classIndex = -1;
for (var i = 0; i < firstDim; i++)
{
var yi = outputGradientReshape.Get(i, b);
if (yi == 1.0f)
{
classIndex = i;
}
}
var pj = outputReshape.Get(classIndex, b);
// input gradient:
// pi(1 - pi) if i = class index
// -pipj if i != class index
for (var i = 0; i < firstDim; i++)
{
var pi = outputReshape.Get(i, b);
if (i == classIndex)
{
inputGradientReshape.Set(i, b, pj * (1.0f - pj));
}
else
{
inputGradientReshape.Set(i, b, -pj * pi);
}
}
}
}
public override void DoSum(Volume <float> result)
{
var batchSize = this.Shape.DimensionCount > 1 ? this.Shape.GetDimension(-1) : 1;
var inputReshape = ReShape(-1, batchSize);
var n = inputReshape.Shape.GetDimension(0);
if (batchSize > 1 && result.Shape.DimensionCount > 1 && result.Shape.GetDimension(3) == 1)
{
var resultReshape = result.ReShape(-1, 1);
for (var j = 0; j < n; j++)
{
var sum = 0.0f;
// Sum over batch
for (var i = 0; i < batchSize; i++)
{
var d = inputReshape.Get(j, i);
sum += d;
}
resultReshape.Set(j, 0, sum);
}
}
else
{
for (var i = 0; i < batchSize; i++)
{
var sum = 0.0f;
for (var j = 0; j < n; j++)
{
var d = inputReshape.Get(j, i);
sum += d;
}
result.Set(new[] { i }, sum);
}
}
}
