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:

java.io.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:

IndexToString for the inverse transformation, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.spark.internal.Logging

org.apache.spark.internal.Logging.SparkShellLoggingFilter

Constructor Summary

Constructors

Constructor and Description
StringIndexer()
StringIndexer(String uid)

Method Summary

Modifier and Type	Method and Description
StringIndexer	copy(ParamMap extra) Creates a copy of this instance with the same UID and some extra params.
StringIndexerModel	fit(Dataset<?> dataset) Fits a model to the input data.
Param<String>	handleInvalid() Param for how to handle invalid data (unseen labels or NULL values).
Param<String>	inputCol() Param for input column name.
StringArrayParam	inputCols() Param for input column names.
static StringIndexer	load(String path)
Param<String>	outputCol() Param for output column name.
StringArrayParam	outputCols() Param for output column names.
static MLReader<T>	read()
StringIndexer	setHandleInvalid(String value)
StringIndexer	setInputCol(String value)
StringIndexer	setInputCols(String[] value)
StringIndexer	setOutputCol(String value)
StringIndexer	setOutputCols(String[] value)
StringIndexer	setStringOrderType(String value)
Param<String>	stringOrderType() Param for how to order labels of string column.
StructType	transformSchema(StructType schema) Check transform validity and derive the output schema from the input schema.
String	uid() An immutable unique ID for the object and its derivatives.

Methods inherited from class org.apache.spark.ml.Estimator

fit, fit, fit, fit

Methods inherited from class org.apache.spark.ml.PipelineStage

params

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.spark.ml.feature.StringIndexerBase

getInOutCols, getStringOrderType, validateAndTransformField, validateAndTransformSchema

Methods inherited from interface org.apache.spark.ml.param.shared.HasHandleInvalid

getHandleInvalid

Methods inherited from interface org.apache.spark.ml.param.shared.HasInputCol

getInputCol

Methods inherited from interface org.apache.spark.ml.param.shared.HasOutputCol

getOutputCol

Methods inherited from interface org.apache.spark.ml.param.shared.HasInputCols

getInputCols

Methods inherited from interface org.apache.spark.ml.param.shared.HasOutputCols

getOutputCols

Methods inherited from interface org.apache.spark.ml.param.Params

clear, copyValues, defaultCopy, defaultParamMap, explainParam, explainParams, extractParamMap, extractParamMap, get, getDefault, getOrDefault, getParam, hasDefault, hasParam, isDefined, isSet, paramMap, params, set, set, set, setDefault, setDefault, shouldOwn

Methods inherited from interface org.apache.spark.ml.util.Identifiable

toString

Methods inherited from interface org.apache.spark.ml.util.DefaultParamsWritable

write

Methods inherited from interface org.apache.spark.ml.util.MLWritable

save

Methods inherited from interface org.apache.spark.internal.Logging

$init$, initializeForcefully, initializeLogIfNecessary, initializeLogIfNecessary, initializeLogIfNecessary$default$2, initLock, isTraceEnabled, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning, org$apache$spark$internal$Logging$$log__$eq, org$apache$spark$internal$Logging$$log_, uninitialize

Constructor Detail

StringIndexer

public StringIndexer(String uid)

StringIndexer

public StringIndexer()

Method Detail

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 StringIndexerBase

Specified by:

handleInvalid in interface HasHandleInvalid

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)