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(in src, i, keyCounts[i]);
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(in 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(in 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(in 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);
}
private SequencePool[] Train(Arguments args, IDataView trainingData, out double[][] invDocFreqs)
{
// Contains the maximum number of grams to store in the dictionary, for each level of ngrams,
// from 1 (in position 0) up to ngramLength (in position ngramLength-1)
var lims = new int[Infos.Length][];
for (int iinfo = 0; iinfo < Infos.Length; iinfo++)
{
var all = args.Column[iinfo].AllLengths ?? args.AllLengths;
var ngramLength = _exes[iinfo].NgramLength;
var maxNumTerms = Utils.Size(args.Column[iinfo].MaxNumTerms) > 0 ? args.Column[iinfo].MaxNumTerms : args.MaxNumTerms;
if (!all)
{
Host.CheckUserArg(Utils.Size(maxNumTerms) == 0 ||
Utils.Size(maxNumTerms) == 1 && maxNumTerms[0] > 0, nameof(args.MaxNumTerms));
lims[iinfo] = new int[ngramLength];
lims[iinfo][ngramLength - 1] = Utils.Size(maxNumTerms) == 0 ? Arguments.DefaultMaxTerms : maxNumTerms[0];
}
else
{
Host.CheckUserArg(Utils.Size(maxNumTerms) <= ngramLength, nameof(args.MaxNumTerms));
Host.CheckUserArg(Utils.Size(maxNumTerms) == 0 || maxNumTerms.All(i => i >= 0) && maxNumTerms[maxNumTerms.Length - 1] > 0, nameof(args.MaxNumTerms));
var extend = Utils.Size(maxNumTerms) == 0 ? Arguments.DefaultMaxTerms : maxNumTerms[maxNumTerms.Length - 1];
lims[iinfo] = Utils.BuildArray(ngramLength,
i => i < Utils.Size(maxNumTerms) ? maxNumTerms[i] : extend);
}
}
var helpers = new NgramBufferBuilder[Infos.Length];
var getters = new ValueGetter <VBuffer <uint> > [Infos.Length];
var src = new VBuffer <uint> [Infos.Length];
// Keep track of how many grams are in the pool for each value of n. Position
// i in _counts counts how many (i+1)-grams are in the pool for column iinfo.
var counts = new int[Infos.Length][];
var ngramMaps = new SequencePool[Infos.Length];
bool[] activeInput = new bool[trainingData.Schema.ColumnCount];
foreach (var info in Infos)
{
activeInput[info.Source] = true;
}
using (var cursor = trainingData.GetRowCursor(col => activeInput[col]))
using (var pch = Host.StartProgressChannel("Building n-gram dictionary"))
{
for (int iinfo = 0; iinfo < Infos.Length; iinfo++)
{
Host.Assert(Infos[iinfo].TypeSrc.IsVector && Infos[iinfo].TypeSrc.ItemType.IsKey);
var ngramLength = _exes[iinfo].NgramLength;
var skipLength = _exes[iinfo].SkipLength;
getters[iinfo] = RowCursorUtils.GetVecGetterAs <uint>(NumberType.U4, cursor, Infos[iinfo].Source);
src[iinfo] = default(VBuffer <uint>);
counts[iinfo] = new int[ngramLength];
ngramMaps[iinfo] = new SequencePool();
// Note: GetNgramIdFinderAdd will control how many ngrams of a specific length will
// be added (using lims[iinfo]), therefore we set slotLim to the maximum
helpers[iinfo] = new NgramBufferBuilder(ngramLength, skipLength, Utils.ArrayMaxSize,
GetNgramIdFinderAdd(counts[iinfo], lims[iinfo], ngramMaps[iinfo], _exes[iinfo].RequireIdf(), Host));
}
int cInfoFull = 0;
bool[] infoFull = new bool[Infos.Length];
invDocFreqs = new double[Infos.Length][];
long totalDocs = 0;
Double rowCount = trainingData.GetRowCount() ?? Double.NaN;
var buffers = new VBuffer <float> [Infos.Length];
pch.SetHeader(new ProgressHeader(new[] { "Total n-grams" }, new[] { "documents" }),
e => e.SetProgress(0, totalDocs, rowCount));
while (cInfoFull < Infos.Length && cursor.MoveNext())
{
totalDocs++;
for (int iinfo = 0; iinfo < Infos.Length; iinfo++)
{
getters[iinfo](ref src[iinfo]);
var keyCount = (uint)Infos[iinfo].TypeSrc.ItemType.KeyCount;
if (keyCount == 0)
{
keyCount = uint.MaxValue;
}
if (!infoFull[iinfo])
{
if (_exes[iinfo].RequireIdf())
{
helpers[iinfo].Reset();
}
helpers[iinfo].AddNgrams(in src[iinfo], 0, keyCount);
if (_exes[iinfo].RequireIdf())
{
int totalNgrams = counts[iinfo].Sum();
Utils.EnsureSize(ref invDocFreqs[iinfo], totalNgrams);
helpers[iinfo].GetResult(ref buffers[iinfo]);
foreach (var pair in buffers[iinfo].Items())
{
if (pair.Value >= 1)
{
invDocFreqs[iinfo][pair.Key] += 1;
}
}
}
}
AssertValid(counts[iinfo], lims[iinfo], ngramMaps[iinfo]);
}
}
pch.Checkpoint(counts.Sum(c => c.Sum()), totalDocs);
for (int iinfo = 0; iinfo < Infos.Length; iinfo++)
{
for (int i = 0; i < Utils.Size(invDocFreqs[iinfo]); i++)
{
if (invDocFreqs[iinfo][i] != 0)
{
invDocFreqs[iinfo][i] = Math.Log(totalDocs / invDocFreqs[iinfo][i]);
}
}
}
for (int iinfo = 0; iinfo < Infos.Length; iinfo++)
{
AssertValid(counts[iinfo], lims[iinfo], ngramMaps[iinfo]);
int ngramLength = _exes[iinfo].NgramLength;
for (int i = 0; i < ngramLength; i++)
{
_exes[iinfo].NonEmptyLevels[i] = counts[iinfo][i] > 0;
}
}
return(ngramMaps);
}
}
