private Delegate MakeGetter(IChannel ch, IRow input, int iinfo, FinderDecorator decorator = null)
{
ch.Assert(_bindings.Infos[iinfo].SrcTypes.All(t => t.IsVector && t.ItemType.IsKey));
var info = _bindings.Infos[iinfo];
int srcCount = info.SrcIndices.Length;
ValueGetter <VBuffer <uint> >[] getSrc = new ValueGetter <VBuffer <uint> > [srcCount];
for (int isrc = 0; isrc < srcCount; isrc++)
{
getSrc[isrc] = RowCursorUtils.GetVecGetterAs <uint>(NumberType.U4, input, info.SrcIndices[isrc]);
}
var src = default(VBuffer <uint>);
var ngramIdFinder = GetNgramIdFinder(iinfo);
if (decorator != null)
{
ngramIdFinder = decorator(iinfo, ngramIdFinder);
}
var bldr = new NgramBufferBuilder(_exes[iinfo].NgramLength, _exes[iinfo].SkipLength,
_bindings.Types[iinfo].ValueCount, ngramIdFinder);
var keyCounts = _bindings.Infos[iinfo].SrcTypes.Select(
t => t.ItemType.KeyCount > 0 ? (uint)t.ItemType.KeyCount : uint.MaxValue).ToArray();
// REVIEW: Special casing the srcCount==1 case could potentially improve perf.
ValueGetter <VBuffer <Float> > del =
(ref VBuffer <Float> dst) =>
{
bldr.Reset();
for (int i = 0; i < srcCount; i++)
{
getSrc[i](ref src);
bldr.AddNgrams(ref src, i, keyCounts[i]);
}
bldr.GetResult(ref dst);
};
return(del);
}
protected override Delegate GetGetterCore(IChannel ch, IRow input, int iinfo, out Action disposer)
{
Host.AssertValueOrNull(ch);
Host.AssertValue(input);
Host.Assert(0 <= iinfo && iinfo < Infos.Length);
Host.Assert(Infos[iinfo].TypeSrc.IsVector);
Host.Assert(Infos[iinfo].TypeSrc.ItemType.IsKey);
disposer = null;
var getSrc = RowCursorUtils.GetVecGetterAs <uint>(NumberType.U4, input, Infos[iinfo].Source);
var src = default(VBuffer <uint>);
var bldr = new NgramBufferBuilder(_exes[iinfo].NgramLength, _exes[iinfo].SkipLength,
_ngramMaps[iinfo].Count, GetNgramIdFinder(iinfo));
var keyCount = (uint)Infos[iinfo].TypeSrc.ItemType.KeyCount;
if (keyCount == 0)
{
keyCount = uint.MaxValue;
}
ValueGetter <VBuffer <Float> > del;
switch (_exes[iinfo].Weighting)
{
case WeightingCriteria.TfIdf:
Host.AssertValue(_invDocFreqs[iinfo]);
del =
(ref VBuffer <Float> dst) =>
{
getSrc(ref src);
if (!bldr.IsEmpty)
{
bldr.Reset();
bldr.AddNgrams(ref src, 0, keyCount);
bldr.GetResult(ref dst);
VBufferUtils.Apply(ref dst, (int i, ref Float v) => v = (Float)(v * _invDocFreqs[iinfo][i]));
}
else
{
dst = new VBuffer <Float>(0, dst.Values, dst.Indices);
}
};
break;
case WeightingCriteria.Idf:
Host.AssertValue(_invDocFreqs[iinfo]);
del =
(ref VBuffer <Float> dst) =>
{
getSrc(ref src);
if (!bldr.IsEmpty)
{
bldr.Reset();
bldr.AddNgrams(ref src, 0, keyCount);
bldr.GetResult(ref dst);
VBufferUtils.Apply(ref dst, (int i, ref Float v) => v = v >= 1 ? (Float)_invDocFreqs[iinfo][i] : 0);
}
else
{
dst = new VBuffer <Float>(0, dst.Values, dst.Indices);
}
};
break;
case WeightingCriteria.Tf:
del =
(ref VBuffer <Float> dst) =>
{
getSrc(ref src);
if (!bldr.IsEmpty)
{
bldr.Reset();
bldr.AddNgrams(ref src, 0, keyCount);
bldr.GetResult(ref dst);
}
else
{
dst = new VBuffer <Float>(0, dst.Values, dst.Indices);
}
};
break;
default:
throw Host.Except("Unsupported weighting criteria");
}
return(del);
}
