private void CombineCore(ref VBuffer <Single> dst, VBuffer <Single>[] src, Single[] weights = null)
{
Host.AssertNonEmpty(src);
Host.Assert(weights == null || Utils.Size(weights) == Utils.Size(src));
int count = Utils.Size(src);
if (count == 0)
{
dst = new VBuffer <Single>(0, dst.Values, dst.Indices);
return;
}
int len = GetClassCount(src);
var values = dst.Values;
if (Utils.Size(values) < len)
{
values = new Single[len];
}
else
{
Array.Clear(values, 0, len);
}
int voteCount = 0;
for (int i = 0; i < count; i++)
{
int index = VectorUtils.ArgMax(ref src[i]);
if (index >= 0)
{
values[index]++;
voteCount++;
}
}
// Normalize by dividing by the number of votes.
for (int i = 0; i < len; i++)
{
values[i] /= voteCount;
}
// Set the output to values.
dst = new VBuffer <Single>(len, values, dst.Indices);
}
protected override Delegate GetPredictedLabelGetter(IRow output, out Delegate scoreGetter)
{
Host.AssertValue(output);
Host.Assert(output.Schema == Bindings.RowMapper.Schema);
Host.Assert(output.IsColumnActive(Bindings.ScoreColumnIndex));
ValueGetter <VBuffer <Float> > mapperScoreGetter = output.GetGetter <VBuffer <Float> >(Bindings.ScoreColumnIndex);
long cachedPosition = -1;
VBuffer <Float> score = default(VBuffer <Float>);
int scoreLength = Bindings.PredColType.KeyCount;
ValueGetter <uint> predFn =
(ref uint dst) =>
{
EnsureCachedPosition(ref cachedPosition, ref score, output, mapperScoreGetter);
Host.Check(score.Length == scoreLength);
int index = VectorUtils.ArgMax(ref score);
if (index < 0)
{
dst = 0;
}
else
{
dst = (uint)index + 1;
}
};
ValueGetter <VBuffer <Float> > scoreFn =
(ref VBuffer <Float> dst) =>
{
EnsureCachedPosition(ref cachedPosition, ref score, output, mapperScoreGetter);
Host.Check(score.Length == scoreLength);
score.CopyTo(ref dst);
};
scoreGetter = scoreFn;
return(predFn);
}
protected override Single GetDifference(ref VBuffer <Single> valueX, ref VBuffer <Single> valueY)
{
return((VectorUtils.ArgMax(ref valueX) != VectorUtils.ArgMax(ref valueY)) ? 1 : 0);
}