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");
            h.CheckUserArg(args.Tokenizer != null, nameof(args.Tokenizer), "tokenizer must be specified");

            // To each input column to the WordHashBagTransform, a tokenize transform is applied,
            // followed by applying WordHashVectorizeTransform.
            // Since WordHashBagTransform is a many-to-one column transform, for each
            // WordHashBagTransform.Column we may need to define multiple tokenize transform columns.
            // NgramHashExtractorTransform may need to define an identical number of HashTransform.Columns.
            // The intermediate columns are dropped at the end of using a DropColumnsTransform.
            IDataView view = input;

            var uniqueSourceNames = NgramExtractionUtils.GenerateUniqueSourceNames(h, args.Column, view.Schema);

            Contracts.Assert(uniqueSourceNames.Length == args.Column.Length);

            var           tokenizeColumns = new List <WordBagTransform.TokenizeColumn>();
            var           extractorCols   = new NgramHashExtractorTransform.Column[args.Column.Length];
            var           colCount        = args.Column.Length;
            List <string> tmpColNames     = new List <string>();

            for (int iinfo = 0; iinfo < colCount; iinfo++)
            {
                var column      = args.Column[iinfo];
                int srcCount    = column.Source.Length;
                var curTmpNames = new string[srcCount];
                Contracts.Assert(uniqueSourceNames[iinfo].Length == args.Column[iinfo].Source.Length);
                for (int isrc = 0; isrc < srcCount; isrc++)
                {
                    tokenizeColumns.Add(
                        new WordBagTransform.TokenizeColumn
                    {
                        Name   = curTmpNames[isrc] = uniqueSourceNames[iinfo][isrc],
                        Source = args.Column[iinfo].Source[isrc]
                    });
                }

                tmpColNames.AddRange(curTmpNames);
                extractorCols[iinfo] =
                    new NgramHashExtractorTransform.Column
                {
                    Name          = column.Name,
                    Source        = curTmpNames,
                    HashBits      = column.HashBits,
                    NgramLength   = column.NgramLength,
                    Seed          = column.Seed,
                    SkipLength    = column.SkipLength,
                    Ordered       = column.Ordered,
                    InvertHash    = column.InvertHash,
                    FriendlyNames = args.Column[iinfo].Source,
                    AllLengths    = column.AllLengths
                };
            }

            view = args.Tokenizer.CreateComponent(h, view, tokenizeColumns.ToArray());

            var featurizeArgs =
                new NgramHashExtractorTransform.Arguments
            {
                AllLengths  = args.AllLengths,
                HashBits    = args.HashBits,
                NgramLength = args.NgramLength,
                SkipLength  = args.SkipLength,
                Ordered     = args.Ordered,
                Seed        = args.Seed,
                Column      = extractorCols.ToArray(),
                InvertHash  = args.InvertHash
            };

            view = NgramHashExtractorTransform.Create(h, featurizeArgs, view);

            // Since we added columns with new names, we need to explicitly drop them before we return the IDataTransform.
            var dropColsArgs =
                new DropColumnsTransform.Arguments()
            {
                Column = tmpColNames.ToArray()
            };

            return(new DropColumnsTransform(h, dropColsArgs, view));
        }
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 public IDataTransform Create(IHostEnvironment env, IDataView input, ExtractorColumn[] cols)
 {
     return(NgramHashExtractorTransform.Create(_extractorArgs, env, input, cols, _termLoaderArgs));
 }