OneHotEncoder (Spark 2.1.2 JavaDoc)

Object
- org.apache.spark.ml.PipelineStage
- - org.apache.spark.ml.Transformer
  - - org.apache.spark.ml.feature.OneHotEncoder

All Implemented Interfaces:

java.io.Serializable, Params, DefaultParamsWritable, Identifiable, MLWritable
```
public class OneHotEncoder
extends Transformer
implements DefaultParamsWritable
```
A one-hot encoder that maps a column of category indices to a column of binary vectors, with at most a single one-value per row that indicates the input category index. For example with 5 categories, an input value of 2.0 would map to an output vector of [0.0, 0.0, 1.0, 0.0]. The last category is not included by default (configurable via OneHotEncoder!.dropLast because it makes the vector entries sum up to one, and hence linearly dependent. So an input value of 4.0 maps to [0.0, 0.0, 0.0, 0.0].

See Also:
StringIndexer for converting categorical values into category indices, Serialized Form
Note:

This is different from scikit-learn's OneHotEncoder, which keeps all categories. The output vectors are sparse.

Constructor Summary

Constructors
Constructor and Description

OneHotEncoder()

OneHotEncoder(String uid)

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

Method Summary

Methods
Modifier and Type	Method and Description
`static Params`	`clear(Param<?> param)`
`OneHotEncoder`	`copy(ParamMap extra)` Creates a copy of this instance with the same UID and some extra params.
`BooleanParam`	`dropLast()` Whether to drop the last category in the encoded vector (default: true)
`static String`	`explainParam(Param<?> param)`
`static String`	`explainParams()`
`static ParamMap`	`extractParamMap()`
`static ParamMap`	`extractParamMap(ParamMap extra)`
`static <T> scala.Option<T>`	`get(Param<T> param)`
`static <T> scala.Option<T>`	`getDefault(Param<T> param)`
`boolean`	`getDropLast()`
`static String`	`getInputCol()`
`static <T> T`	`getOrDefault(Param<T> param)`
`static String`	`getOutputCol()`
`static Param<Object>`	`getParam(String paramName)`
`static <T> boolean`	`hasDefault(Param<T> param)`
`static boolean`	`hasParam(String paramName)`
`static Param<String>`	`inputCol()`
`static boolean`	`isDefined(Param<?> param)`
`static boolean`	`isSet(Param<?> param)`
`static OneHotEncoder`	`load(String path)`
`static Param<String>`	`outputCol()`
`static Param<?>[]`	`params()`
`static void`	`save(String path)`
`static <T> Params`	`set(Param<T> param, T value)`
`OneHotEncoder`	`setDropLast(boolean value)`
`OneHotEncoder`	`setInputCol(String value)`
`OneHotEncoder`	`setOutputCol(String value)`
`static String`	`toString()`
`Dataset<Row>`	`transform(Dataset<?> dataset)` Transforms the input dataset.
`StructType`	`transformSchema(StructType schema)` :: DeveloperApi ::
`String`	`uid()` An immutable unique ID for the object and its derivatives.
`static MLWriter`	`write()`

Methods inherited from class org.apache.spark.ml.Transformer
transform, transform, transform

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

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.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

- Constructor Detail
  - OneHotEncoder
```
public OneHotEncoder(String uid)
```
  - OneHotEncoder
```
public OneHotEncoder()
```
- Method Detail
  - load
```
public static OneHotEncoder 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()
```
  - 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)
  - dropLast
```
public final BooleanParam dropLast()
```
    Whether to drop the last category in the encoded vector (default: true)
    
    Returns:
    (undocumented)
  - getDropLast
```
public boolean getDropLast()
```
  - setDropLast
```
public OneHotEncoder setDropLast(boolean value)
```
  - setInputCol
```
public OneHotEncoder setInputCol(String value)
```
  - setOutputCol
```
public OneHotEncoder setOutputCol(String value)
```
  - transformSchema
```
public StructType transformSchema(StructType schema)
```
    Description copied from class: PipelineStage
    
    :: DeveloperApi ::
    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)
  - transform
```
public Dataset<Row> transform(Dataset<?> dataset)
```
    Description copied from class: Transformer
    
    Transforms the input dataset.
    
    Specified by:
    
    transform in class Transformer
    
    Parameters:
    dataset - (undocumented)
    
    Returns:
    (undocumented)
  - copy
```
public OneHotEncoder 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 Transformer
    
    Parameters:
    extra - (undocumented)
    
    Returns:
    (undocumented)

Class OneHotEncoder

Constructor Summary

Method Summary

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

Methods inherited from class Object

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.ml.param.Params

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

Constructor Detail

OneHotEncoder

OneHotEncoder

Method Detail

load

toString

params

explainParam

explainParams

isSet

isDefined

hasParam

getParam

set

get

clear

getOrDefault

getDefault

hasDefault

extractParamMap

extractParamMap

inputCol

getInputCol

outputCol

getOutputCol

save

write

uid

dropLast

getDropLast

setDropLast

setInputCol

setOutputCol

transformSchema

transform

copy