internal CountTargetEncodingEstimator(IHostEnvironment env, Options options) { Contracts.CheckValue(env, nameof(env)); _host = env.Register(nameof(CountTargetEncodingEstimator)); _host.CheckValue(options, nameof(options)); _host.CheckUserArg(Utils.Size(options.Columns) > 0, nameof(options.Columns), "Columns must be specified"); _host.CheckUserArg(!string.IsNullOrWhiteSpace(options.LabelColumn), nameof(options.LabelColumn), "Must specify the label column name"); if (!string.IsNullOrEmpty(options.InitialCountsModel)) { _countTableEstimator = LoadFromFile(env, options.InitialCountsModel, options.LabelColumn, options.Columns.Select(col => new InputOutputColumnPair(col.Name)).ToArray()); if (_countTableEstimator == null) { throw env.Except($"The file {options.InitialCountsModel} does not contain a CountTableTransformer"); } } else if (options.SharedTable) { var columns = new CountTableEstimator.SharedColumnOptions[options.Columns.Length]; for (int i = 0; i < options.Columns.Length; i++) { var column = options.Columns[i]; columns[i] = new CountTableEstimator.SharedColumnOptions( column.Name, column.Name, column.PriorCoefficient ?? options.PriorCoefficient, column.LaplaceScale ?? options.LaplaceScale, column.Seed ?? options.Seed); } var builder = options.CountTable; _host.CheckValue(builder, nameof(options.CountTable)); _countTableEstimator = new CountTableEstimator(_host, options.LabelColumn, builder.CreateComponent(_host), columns); } else { var columns = new CountTableEstimator.ColumnOptions[options.Columns.Length]; for (int i = 0; i < options.Columns.Length; i++) { var column = options.Columns[i]; var builder = column.CountTable ?? options.CountTable; _host.CheckValue(builder, nameof(options.CountTable)); columns[i] = new CountTableEstimator.ColumnOptions( column.Name, column.Name, builder.CreateComponent(_host), column.PriorCoefficient ?? options.PriorCoefficient, column.LaplaceScale ?? options.LaplaceScale, column.Seed ?? options.Seed); } _countTableEstimator = new CountTableEstimator(_host, options.LabelColumn, columns); } _hashingColumns = InitializeHashingColumnOptions(options); _hashingEstimator = new HashingEstimator(_host, _hashingColumns); }
/// <summary> /// Transforms a categorical column into a set of features that includes the count of each label class, /// the log-odds for each label class and the back-off indicator. /// </summary> /// <param name="catalog">The transforms catalog.</param> /// <param name="columns">The input and output columns.</param> /// <param name="labelColumn">The name of the label column.</param> /// <param name="builder">The builder that creates the count tables from the training data.</param> /// <param name="priorCoefficient">The coefficient with which to apply the prior smoothing to the features.</param> /// <param name="laplaceScale">The Laplacian noise diversity/scale-parameter. Recommended values are between 0 and 1. Note that the noise /// will only be applied if the estimator is part of an <see cref="EstimatorChain{TLastTransformer}"/>, when fitting the next estimator in the chain.</param> /// <param name="sharedTable">Indicates whether to keep counts for all columns and slots in one shared count table. If true, the keys in the count table /// will include a hash of the column and slot indices.</param> /// <param name="numberOfBits">The number of bits to hash the input into. Must be between 1 and 31, inclusive.</param> /// <param name="combine">In case the input is a vector column, indicates whether the values should be combined into a single hash to create a single /// count table, or be left as a vector of hashes with multiple count tables.</param> /// <param name="hashingSeed">The seed used for hashing the input columns.</param> /// <returns></returns> public static CountTargetEncodingEstimator CountTargetEncode(this TransformsCatalog catalog, InputOutputColumnPair[] columns, string labelColumn = DefaultColumnNames.Label, CountTableBuilderBase builder = null, float priorCoefficient = CountTableTransformer.Defaults.PriorCoefficient, float laplaceScale = CountTableTransformer.Defaults.LaplaceScale, bool sharedTable = CountTableTransformer.Defaults.SharedTable, int numberOfBits = HashingEstimator.Defaults.NumberOfBits, bool combine = HashingEstimator.Defaults.Combine, uint hashingSeed = HashingEstimator.Defaults.Seed) { var env = CatalogUtils.GetEnvironment(catalog); env.CheckValue(columns, nameof(columns)); builder = builder ?? new CMCountTableBuilder(); CountTargetEncodingEstimator estimator; if (sharedTable) { var columnOptions = new CountTableEstimator.SharedColumnOptions[columns.Length]; for (int i = 0; i < columns.Length; i++) { columnOptions[i] = new CountTableEstimator.SharedColumnOptions( columns[i].OutputColumnName, columns[i].InputColumnName, priorCoefficient, laplaceScale); } estimator = new CountTargetEncodingEstimator(env, labelColumn, columnOptions, builder, numberOfBits, combine, hashingSeed); } else { var columnOptions = new CountTableEstimator.ColumnOptions[columns.Length]; for (int i = 0; i < columns.Length; i++) { columnOptions[i] = new CountTableEstimator.ColumnOptions( columns[i].OutputColumnName, columns[i].InputColumnName, builder, priorCoefficient, laplaceScale); } estimator = new CountTargetEncodingEstimator(env, labelColumn, columnOptions, numberOfBits: numberOfBits, combine: combine, hashingSeed: hashingSeed); } return(estimator); }