/// <summary>
/// Describes how the transformer handles one column pair.
/// </summary>
/// <param name="name">Name of the column resulting from the transformation of <paramref name="inputColumnName"/>.</param>
/// <param name="inputColumnName">Name of the column to transform. If set to <see langword="null"/>, the value of the <paramref name="name"/> will be used as source.</param>
/// <param name="outputKind">Output kind: Bag (multi-set vector), Ind (indicator vector), Key (index), or Binary encoded indicator vector.</param>
/// <param name="maxNumTerms">Maximum number of terms to keep per column when auto-training.</param>
/// <param name="sort">How items should be ordered when vectorized. If <see cref="ValueToKeyMappingEstimator.SortOrder.Occurrence"/> choosen they will be in the order encountered.
/// If <see cref="ValueToKeyMappingEstimator.SortOrder.Value"/>, items are sorted according to their default comparison, for example, text sorting will be case sensitive (for example, 'A' then 'Z' then 'a').</param>
/// <param name="term">List of terms.</param>
public ColumnOptions(string name, string inputColumnName = null,
OneHotEncodingTransformer.OutputKind outputKind = Defaults.OutKind,
int maxNumTerms = ValueToKeyMappingEstimator.Defaults.MaxNumKeys, ValueToKeyMappingEstimator.SortOrder sort = ValueToKeyMappingEstimator.Defaults.Sort,
string[] term = null)
: base(name, inputColumnName ?? name, maxNumTerms, sort, term, true)
{
OutputKind = outputKind;
}
/// <summary>
/// Converts value types into <see cref="KeyType"/>.
/// </summary>
/// <param name="catalog">The categorical transform's catalog.</param>
/// <param name="outputColumnName">Name of the column resulting from the transformation of <paramref name="inputColumnName"/>.</param>
/// <param name="inputColumnName">Name of the column to transform. If set to <see langword="null"/>, the value of the <paramref name="outputColumnName"/> will be used as source.</param>
/// <param name="maxNumKeys">Maximum number of keys to keep per column when auto-training.</param>
/// <param name="sort">How items should be ordered when vectorized. If <see cref="ValueToKeyMappingEstimator.SortOrder.Occurrence"/> choosen they will be in the order encountered.
/// If <see cref="ValueToKeyMappingEstimator.SortOrder.Value"/>, items are sorted according to their default comparison, for example, text sorting will be case sensitive (for example, 'A' then 'Z' then 'a').</param>
/// <example>
/// <format type="text/markdown">
/// <]
/// ]]>
/// </format>
/// </example>
public static ValueToKeyMappingEstimator MapValueToKey(this TransformsCatalog.ConversionTransforms catalog,
string outputColumnName,
string inputColumnName = null,
int maxNumKeys = ValueToKeyMappingEstimator.Defaults.MaxNumKeys,
ValueToKeyMappingEstimator.SortOrder sort = ValueToKeyMappingEstimator.Defaults.Sort)
=> new ValueToKeyMappingEstimator(CatalogUtils.GetEnvironment(catalog), outputColumnName, inputColumnName, maxNumKeys, sort);
