StringIndexer (Spark 2.2.1 JavaDoc)

Object
- org.apache.spark.ml.PipelineStage
- - org.apache.spark.ml.Estimator<StringIndexerModel>
  - - org.apache.spark.ml.feature.StringIndexer

All Implemented Interfaces:

java.io.Serializable, Logging, Params, DefaultParamsWritable, Identifiable, MLWritable
```
public class StringIndexer
extends Estimator<StringIndexerModel>
implements DefaultParamsWritable
```
A label indexer that maps a string column of labels to an ML column of label indices. If the input column is numeric, we cast it to string and index the string values. The indices are in [0, numLabels), ordered by label frequencies. So the most frequent label gets index 0.

See Also:

IndexToString for the inverse transformation, Serialized Form

Constructor Summary

Constructors
Constructor and Description

StringIndexer()

StringIndexer(String uid)

Constructors
Constructor and Description
`StringIndexer()`
`StringIndexer(String uid)`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`static Params`	`clear(Param<?> param)`
`StringIndexer`	`copy(ParamMap extra)` Creates a copy of this instance with the same UID and some extra params.
`static String`	`explainParam(Param<?> param)`
`static String`	`explainParams()`
`static ParamMap`	`extractParamMap()`
`static ParamMap`	`extractParamMap(ParamMap extra)`
`StringIndexerModel`	`fit(Dataset<?> dataset)` Fits a model to the input data.
`static <T> scala.Option<T>`	`get(Param<T> param)`
`static <T> scala.Option<T>`	`getDefault(Param<T> param)`
`static String`	`getHandleInvalid()`
`String`	`getHandleInvalid()`
`static String`	`getInputCol()`
`String`	`getInputCol()`
`static <T> T`	`getOrDefault(Param<T> param)`
`static String`	`getOutputCol()`
`String`	`getOutputCol()`
`static Param<Object>`	`getParam(String paramName)`
`static Param<String>`	`handleInvalid()`
`Param<String>`	`handleInvalid()` Param for how to handle invalid data (unseen labels or NULL values).
`static <T> boolean`	`hasDefault(Param<T> param)`
`static boolean`	`hasParam(String paramName)`
`static Param<String>`	`inputCol()`
`Param<String>`	`inputCol()` Param for input column name.
`static boolean`	`isDefined(Param<?> param)`
`static boolean`	`isSet(Param<?> param)`
`static StringIndexer`	`load(String path)`
`static Param<String>`	`outputCol()`
`Param<String>`	`outputCol()` Param for output column name.
`static Param<?>[]`	`params()`
`static void`	`save(String path)`
`static <T> Params`	`set(Param<T> param, T value)`
`StringIndexer`	`setHandleInvalid(String value)`
`StringIndexer`	`setInputCol(String value)`
`StringIndexer`	`setOutputCol(String value)`
`static String`	`toString()`
`StructType`	Developer API`transformSchema(StructType schema)`
`String`	`uid()` An immutable unique ID for the object and its derivatives.
`StructType`	`validateAndTransformSchema(StructType schema)` Validates and transforms the input schema.
`static MLWriter`	`write()`

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

Methods inherited from class Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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
initializeLogging, initializeLogIfNecessary, isTraceEnabled, log_, log, logDebug, logDebug, logError, logError, logInfo, logInfo, logName, logTrace, logTrace, logWarning, logWarning

- Constructor Detail
  - StringIndexer
```
public StringIndexer(String uid)
```
  - StringIndexer
```
public StringIndexer()
```
- Method Detail
  - load
```
public static StringIndexer load(String path)
```
  - toString
```
public static String toString()
```
  - params
```
public static Param<?>[] params()
```
  - explainParam
```
public static String explainParam(Param<?> param)
```
  - explainParams
```
public static String explainParams()
```
  - isSet
```
public static final boolean isSet(Param<?> param)
```
  - isDefined
```
public static final boolean isDefined(Param<?> param)
```
  - hasParam
```
public static boolean hasParam(String paramName)
```
  - getParam
```
public static Param<Object> getParam(String paramName)
```
  - set
```
public static final <T> Params set(Param<T> param,
                                   T value)
```
  - get
```
public static final <T> scala.Option<T> get(Param<T> param)
```
  - clear
```
public static final Params clear(Param<?> param)
```
  - getOrDefault
```
public static final <T> T getOrDefault(Param<T> param)
```
  - getDefault
```
public static final <T> scala.Option<T> getDefault(Param<T> param)
```
  - hasDefault
```
public static final <T> boolean hasDefault(Param<T> param)
```
  - extractParamMap
```
public static final ParamMap extractParamMap(ParamMap extra)
```
  - extractParamMap
```
public static final ParamMap extractParamMap()
```
  - inputCol
```
public static final Param<String> inputCol()
```
  - getInputCol
```
public static final String getInputCol()
```
  - outputCol
```
public static final Param<String> outputCol()
```
  - getOutputCol
```
public static final String getOutputCol()
```
  - handleInvalid
```
public static Param<String> handleInvalid()
```
  - getHandleInvalid
```
public static String getHandleInvalid()
```
  - save
```
public static void save(String path)
                 throws java.io.IOException
```
    Throws:
    
    java.io.IOException
  - write
```
public static MLWriter write()
```
  - 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)
```
  - setInputCol
```
public StringIndexer setInputCol(String value)
```
  - setOutputCol
```
public StringIndexer setOutputCol(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)
  - Developer API
    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)
  - handleInvalid
```
public Param<String> handleInvalid()
```
    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"
    
    Returns:
    
    (undocumented)
  - getHandleInvalid
```
public String getHandleInvalid()
```
  - validateAndTransformSchema
```
public StructType validateAndTransformSchema(StructType schema)
```
    Validates and transforms the input schema.
  - inputCol
```
public Param<String> inputCol()
```
    Param for input column name.
    
    Returns:
    
    (undocumented)
  - getInputCol
```
public String getInputCol()
```
  - outputCol
```
public Param<String> outputCol()
```
    Param for output column name.
    
    Returns:
    
    (undocumented)
  - getOutputCol
```
public String getOutputCol()
```

Class StringIndexer

Constructor Summary

Method Summary

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

Methods inherited from class Object

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

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

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

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

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

Constructor Detail

StringIndexer

StringIndexer

Method Detail

load

toString

params

explainParam

explainParams

isSet

isDefined

hasParam

getParam

set

get

clear

getOrDefault

getDefault

hasDefault

extractParamMap

extractParamMap

inputCol

getInputCol

outputCol

getOutputCol

handleInvalid

getHandleInvalid

save

write

uid

setHandleInvalid

setInputCol

setOutputCol

fit

transformSchema

copy

handleInvalid

getHandleInvalid

validateAndTransformSchema

inputCol

getInputCol

outputCol

getOutputCol