public static CommonOutputs.TransformOutput NGramTransform(IHostEnvironment env, NgramExtractingTransformer.Arguments input)
{
var h = EntryPointUtils.CheckArgsAndCreateHost(env, "NGramTransform", input);
var xf = NgramExtractingTransformer.Create(h, input, input.Data);
return(new CommonOutputs.TransformOutput()
{
Model = new TransformModelImpl(h, xf, input.Data),
OutputData = xf
});
}
public static IDataTransform Create(IHostEnvironment env, Arguments args, IDataView input)
{
Contracts.CheckValue(env, nameof(env));
var h = env.Register(RegistrationName);
h.CheckValue(args, nameof(args));
h.CheckValue(input, nameof(input));
h.CheckUserArg(Utils.Size(args.Column) > 0, nameof(args.Column), "Columns must be specified");
// Compose the WordBagTransform from a tokenize transform,
// followed by a NgramExtractionTransform.
// Since WordBagTransform is a many-to-one column transform, for each
// WordBagTransform.Column with multiple sources, we first apply a ConcatTransform.
// REVIEW: In order to not get ngrams that cross between vector slots, we need to
// enable tokenize transforms to insert a special token between slots.
// REVIEW: In order to make it possible to output separate bags for different columns
// using the same dictionary, we need to find a way to make ConcatTransform remember the boundaries.
var tokenizeColumns = new WordTokenizingTransformer.ColumnInfo[args.Column.Length];
var extractorArgs =
new NgramExtractingTransformer.Arguments()
{
MaxNumTerms = args.MaxNumTerms,
NgramLength = args.NgramLength,
SkipLength = args.SkipLength,
AllLengths = args.AllLengths,
Weighting = args.Weighting,
Column = new NgramExtractingTransformer.Column[args.Column.Length]
};
for (int iinfo = 0; iinfo < args.Column.Length; iinfo++)
{
var column = args.Column[iinfo];
h.CheckUserArg(!string.IsNullOrWhiteSpace(column.Name), nameof(column.Name));
h.CheckUserArg(Utils.Size(column.Source) > 0, nameof(column.Source));
h.CheckUserArg(column.Source.All(src => !string.IsNullOrWhiteSpace(src)), nameof(column.Source));
tokenizeColumns[iinfo] = new WordTokenizingTransformer.ColumnInfo(column.Source.Length > 1 ? column.Name : column.Source[0], column.Name);
extractorArgs.Column[iinfo] =
new NgramExtractingTransformer.Column()
{
Name = column.Name,
Source = column.Name,
MaxNumTerms = column.MaxNumTerms,
NgramLength = column.NgramLength,
SkipLength = column.SkipLength,
Weighting = column.Weighting,
AllLengths = column.AllLengths
};
}
IDataView view = input;
view = NgramExtractionUtils.ApplyConcatOnSources(h, args.Column, view);
view = new WordTokenizingEstimator(env, tokenizeColumns).Fit(view).Transform(view);
return(NgramExtractingTransformer.Create(h, extractorArgs, view));
}