Package elki.outlier.lof

Class LoOP<O>

  • Type Parameters:
    O - type of objects handled by this algorithm
    All Implemented Interfaces:
    Algorithm, OutlierAlgorithm
    @Title("LoOP: Local Outlier Probabilities")
@Description("Variant of the LOF algorithm normalized using statistical values.")
@Reference(authors="Hans-Peter Kriegel, Peer Kr\u00f6ger, Erich Schubert, Arthur Zimek",
           title="LoOP: Local Outlier Probabilities",
           booktitle="Proc. 18th Int. Conf. Information and Knowledge Management (CIKM 2009)",
           url="https://doi.org/10.1145/1645953.1646195",
           bibkey="DBLP:conf/cikm/KriegelKSZ09")
@Priority(200)
public class LoOP<O>
extends java.lang.Object
implements OutlierAlgorithm
    LoOP: Local Outlier Probabilities

    Distance/density based algorithm similar to LOF to detect outliers, but with statistical methods to achieve better result stability.

    Reference:

    Hans-Peter Kriegel, Peer Kröger, Erich Schubert, Arthur Zimek:
    LoOP: Local Outlier Probabilities
    Proc. 18th Int. Conf. Information and Knowledge Management (CIKM 2009)

    Implementation notes:

    • The lambda parameter was removed from the pdist term, because it cancels out.
    • In ELKI 0.7.0, the k parameters have changed by 1 to make them similar to other methods and more intuitive.
    Since:
    0.3
    Author:
    Erich Schubert

    • Field Detail

      • LOG

        private static final Logging LOG
        The logger for this class.

      • kreach

        int kreach
        Reachability neighborhood size.

      • kcomp

        int kcomp
        Comparison neighborhood size.

      • lambda

        double lambda
        Lambda parameter.

      • reachabilityDistance

        protected Distance<? super O> reachabilityDistance
        Distance function for reachability.

      • comparisonDistance

        protected Distance<? super O> comparisonDistance
        Distance function for comparison set.

    • Constructor Detail

      • LoOP

        public LoOP​(int kreach,
            int kcomp,
            Distance<? super O> reachabilityDistance,
            Distance<? super O> comparisonDistance,
            double lambda)
        Constructor with parameters.
        Parameters:
        kreach - k for reachability
        kcomp - k for comparison
        reachabilityDistance - distance function for reachability
        comparisonDistance - distance function for comparison
        lambda - Lambda parameter

    • Method Detail

      • getInputTypeRestriction

        public TypeInformation[] getInputTypeRestriction()
        Description copied from interface: Algorithm
        Get the input type restriction used for negotiating the data query.
        Specified by:
        getInputTypeRestriction in interface Algorithm
        Returns:
        Type restriction

      • run

        public OutlierResult run​(Relation<O> relation)
        Performs the LoOP algorithm on the given database.
        Parameters:
        relation - Relation to process
        Returns:
        Outlier result

      • computePDists

        protected void computePDists​(Relation<O> relation,
                             KNNSearcher<DBIDRef> knn,
                             WritableDoubleDataStore pdists)
        Compute the probabilistic distances used by LoOP.
        Parameters:
        relation - Data relation
        knn - kNN query
        pdists - Storage for distances