Package org.apache.spark.ml.feature

Class StringIndexer

Object
org.apache.spark.ml.PipelineStage
org.apache.spark.ml.Estimator<StringIndexerModel>
org.apache.spark.ml.feature.StringIndexer
All Implemented Interfaces:
Serializable, org.apache.spark.internal.Logging, StringIndexerBase, Params, HasHandleInvalid, HasInputCol, HasInputCols, HasOutputCol, HasOutputCols, DefaultParamsWritable, Identifiable, MLWritable
public class StringIndexer extends Estimator<StringIndexerModel> implements StringIndexerBase, DefaultParamsWritable
A label indexer that maps string column(s) of labels to ML column(s) of label indices. If the input columns are numeric, we cast them to string and index the string values. The indices are in [0, numLabels). By default, this is ordered by label frequencies so the most frequent label gets index 0. The ordering behavior is controlled by setting stringOrderType.

See Also:

  • Constructor Details

    • StringIndexer

      public StringIndexer(String uid)

    • StringIndexer

      public StringIndexer()

  • Method Details

    • load

      public static StringIndexer load(String path)

    • read

      public static MLReader<T> read()

    • handleInvalid

      public Param<String> handleInvalid()
      Description copied from interface: StringIndexerBase
      Param for how to handle invalid data (unseen labels or NULL values). Options are 'skip' (filter out rows with invalid data), 'error' (throw an error), or 'keep' (put invalid data in a special additional bucket, at index numLabels). Default: "error"
      Specified by:
      handleInvalid in interface HasHandleInvalid
      Specified by:
      handleInvalid in interface StringIndexerBase
      Returns:
      (undocumented)

    • stringOrderType

      public final Param<String> stringOrderType()
      Description copied from interface: StringIndexerBase
      Param for how to order labels of string column. The first label after ordering is assigned an index of 0. Options are: - 'frequencyDesc': descending order by label frequency (most frequent label assigned 0) - 'frequencyAsc': ascending order by label frequency (least frequent label assigned 0) - 'alphabetDesc': descending alphabetical order - 'alphabetAsc': ascending alphabetical order Default is 'frequencyDesc'.

      Note: In case of equal frequency when under frequencyDesc/Asc, the strings are further sorted alphabetically.

      Specified by:
      stringOrderType in interface StringIndexerBase
      Returns:
      (undocumented)

    • outputCols

      public final StringArrayParam outputCols()
      Description copied from interface: HasOutputCols
      Param for output column names.
      Specified by:
      outputCols in interface HasOutputCols
      Returns:
      (undocumented)

    • inputCols

      public final StringArrayParam inputCols()
      Description copied from interface: HasInputCols
      Param for input column names.
      Specified by:
      inputCols in interface HasInputCols
      Returns:
      (undocumented)

    • outputCol

      public final Param<String> outputCol()
      Description copied from interface: HasOutputCol
      Param for output column name.
      Specified by:
      outputCol in interface HasOutputCol
      Returns:
      (undocumented)

    • inputCol

      public final Param<String> inputCol()
      Description copied from interface: HasInputCol
      Param for input column name.
      Specified by:
      inputCol in interface HasInputCol
      Returns:
      (undocumented)

    • uid

      public String uid()
      Description copied from interface: Identifiable
      An immutable unique ID for the object and its derivatives.
      Specified by:
      uid in interface Identifiable
      Returns:
      (undocumented)

    • setHandleInvalid

      public StringIndexer setHandleInvalid(String value)

    • setStringOrderType

      public StringIndexer setStringOrderType(String value)

    • setInputCol

      public StringIndexer setInputCol(String value)

    • setOutputCol

      public StringIndexer setOutputCol(String value)

    • setInputCols

      public StringIndexer setInputCols(String[] value)

    • setOutputCols

      public StringIndexer setOutputCols(String[] value)

    • fit

      public StringIndexerModel fit(Dataset<?> dataset)
      Description copied from class: Estimator
      Fits a model to the input data.
      Specified by:
      fit in class Estimator<StringIndexerModel>
      Parameters:
      dataset - (undocumented)
      Returns:
      (undocumented)

    • transformSchema

      public StructType transformSchema(StructType schema)
      Description copied from class: PipelineStage
      Check transform validity and derive the output schema from the input schema.

      We check validity for interactions between parameters during transformSchema and raise an exception if any parameter value is invalid. Parameter value checks which do not depend on other parameters are handled by Param.validate().

      Typical implementation should first conduct verification on schema change and parameter validity, including complex parameter interaction checks.

      Specified by:
      transformSchema in class PipelineStage
      Parameters:
      schema - (undocumented)
      Returns:
      (undocumented)

    • copy

      public StringIndexer copy(ParamMap extra)
      Description copied from interface: Params
      Creates a copy of this instance with the same UID and some extra params. Subclasses should implement this method and set the return type properly. See defaultCopy().
      Specified by:
      copy in interface Params
      Specified by:
      copy in class Estimator<StringIndexerModel>
      Parameters:
      extra - (undocumented)
      Returns:
      (undocumented)