HashNHotEncoder

Transform a collection of categorical features to binary columns, with at most N one-values. Similar to NHotEncoder but uses MurmursHash3 to hash features into buckets to reduce CPU and memory overhead.

Missing values are transformed to zero vectors.

If hashBucketSize is inferred with HLL, the estimate is scaled by sizeScalingFactor to reduce the number of collisions.

Rough table of relationship of scaling factor to % collisions, measured from a corpus of 466544 English words:

sizeScalingFactor     % Collisions
-----------------     ------------
                2     17.9934%
                4     10.5686%
                8      5.7236%
               16      3.0019%
               32      1.5313%
               64      0.7864%
              128      0.3920%
              256      0.1998%
              512      0.0975%
             1024      0.0478%
             2048      0.0236%
             4096      0.0071%

Linear Supertypes

Serializable, Serializable, AnyRef, Any

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
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final def ==(arg0: Any): Boolean

Definition Classes
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def apply(name: String, hashBucketSize: Int = 0, sizeScalingFactor: Double = 8.0): Transformer[Seq[String], HLL, Int]

Create a new HashNHotEncoder instance.
Create a new HashNHotEncoder instance.
hashBucketSize
number of buckets, or 0 to infer from data with HyperLogLog
sizeScalingFactor
when hashBucketSize is 0, scale HLL estimate by this amount
final def asInstanceOf[T0]: T0

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Any
def clone(): AnyRef

Attributes
protected[java.lang]
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AnyRef
Annotations
@throws( ... )
final def eq(arg0: AnyRef): Boolean

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def equals(arg0: Any): Boolean

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def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

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def hashCode(): Int

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final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def ne(arg0: AnyRef): Boolean

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final def notify(): Unit

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final def notifyAll(): Unit

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final def synchronized[T0](arg0: ⇒ T0): T0

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def toString(): String

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final def wait(): Unit

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@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

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@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
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@throws( ... )

Related Doc: package transformers

object HashNHotEncoder extends Serializable

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

def apply(name: String, hashBucketSize: Int = 0, sizeScalingFactor: Double = 8.0): Transformer[Seq[String], HLL, Int]

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

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