Package elki.utilities.scaling.outlier

Class StandardDeviationScaling

  • All Implemented Interfaces:
    OutlierScaling, ScalingFunction
    Direct Known Subclasses:
    MinusLogStandardDeviationScaling
    @Reference(authors="Hans-Peter Kriegel, Peer Kr\u00f6ger, Erich Schubert, Arthur Zimek",
           title="Interpreting and Unifying Outlier Scores",
           booktitle="Proc. 11th SIAM International Conference on Data Mining (SDM 2011)",
           url="https://doi.org/10.1137/1.9781611972818.2",
           bibkey="DBLP:conf/sdm/KriegelKSZ11")
public class StandardDeviationScaling
extends java.lang.Object
implements OutlierScaling
    Scaling that can map arbitrary values to a probability in the range of [0:1].

    Transformation is done using the formula \(\max\{0, \mathrm{erf}(\lambda \frac{x-\mu}{\sigma\sqrt{2}})\}\)

    Where mean can be fixed to a given value, and stddev is then computed against this mean.

    Reference:

    Hans-Peter Kriegel, Peer Kröger, Erich Schubert, Arthur Zimek
    Interpreting and Unifying Outlier Scores
    Proc. 11th SIAM International Conference on Data Mining (SDM 2011)

    Since:
    0.3
    Author:
    Erich Schubert

    • Field Summary

      Fields 
      Modifier and Type Field Description
      (package private) double factor
      Scaling factor to use (usually: Lambda * Stddev * Sqrt(2))
      protected double fixedmean
      Field storing the fixed mean to use
      protected double lambda
      Field storing the lambda value
      (package private) double mean
      Mean to use

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      double getMax()
      Get maximum resulting value.
      double getMin()
      Get minimum resulting value.
      double getScaled​(double value)
      Transform a given value using the scaling function.
      <A> void prepare​(A array, NumberArrayAdapter<?,​A> adapter)
      Prepare is called once for each data set, before getScaled() will be called.
      void prepare​(OutlierResult or)
      Prepare is called once for each data set, before getScaled() will be called.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • fixedmean

        protected double fixedmean
        Field storing the fixed mean to use

      • lambda

        protected double lambda
        Field storing the lambda value

      • mean

        double mean
        Mean to use

      • factor

        double factor
        Scaling factor to use (usually: Lambda * Stddev * Sqrt(2))

    • Constructor Detail

      • StandardDeviationScaling

        public StandardDeviationScaling​(double fixedmean,
                                double lambda)
        Constructor.
        Parameters:
        fixedmean - Fixed mean
        lambda - Scaling factor lambda

      • StandardDeviationScaling

        public StandardDeviationScaling()
        Constructor.

    • Method Detail

      • getScaled

        public double getScaled​(double value)
        Description copied from interface: ScalingFunction
        Transform a given value using the scaling function.
        Specified by:
        getScaled in interface ScalingFunction
        Parameters:
        value - Original value
        Returns:
        Scaled value

      • prepare

        public void prepare​(OutlierResult or)
        Description copied from interface: OutlierScaling
        Prepare is called once for each data set, before getScaled() will be called. This function can be used to extract global parameters such as means, minimums or maximums from the outlier scores.
        Specified by:
        prepare in interface OutlierScaling
        Parameters:
        or - Outlier result to use

      • prepare

        public <A> void prepare​(A array,
                        NumberArrayAdapter<?,​A> adapter)
        Description copied from interface: OutlierScaling
        Prepare is called once for each data set, before getScaled() will be called. This function can be used to extract global parameters such as means, minimums or maximums from the score array. The method using a full OutlierResult is preferred, as it will allow access to the metadata.
        Specified by:
        prepare in interface OutlierScaling
        Parameters:
        array - Data to process
        adapter - Array adapter

      • getMin

        public double getMin()
        Description copied from interface: ScalingFunction
        Get minimum resulting value. May be Double.NaN or Double.NEGATIVE_INFINITY.
        Specified by:
        getMin in interface ScalingFunction
        Returns:
        Minimum resulting value.

      • getMax

        public double getMax()
        Description copied from interface: ScalingFunction
        Get maximum resulting value. May be Double.NaN or Double.POSITIVE_INFINITY.
        Specified by:
        getMax in interface ScalingFunction
        Returns:
        Maximum resulting value.