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Local Outlier Factor#

Local Outlier Factor (LOF) measures the local deviation of density of an unknown sample with respect to its k nearest neighbors from the training set. As such, LOF only considers the local region (or neighborhood) of an unknown sample which enables it to detect anomalies within individual clusters of data.

Interfaces: Estimator, Learner, Ranking, Persistable

Data Type Compatibility: Continuous

Parameters#

# Param Default Type Description
1 k 20 int The k nearest neighbors that form a local region.
2 contamination null float The proportion of outliers that are presumed to be present in the training set.
3 tree KDTree object The spatial tree used to run nearest neighbor searches.

Additional Methods#

Return the base spatial tree instance:

public tree() : Spatial

Example#

use Rubix\ML\AnomalyDetectors\LocalOutlierFactor;
use Rubix\ML\Graph\Trees\BallTree;
use Rubix\ML\Kernels\Distance\Euclidean;

$estimator = new LocalOutlierFactor(20, 0.1, new BallTree(30, new Euclidean));

References#

  • M. M. Breunig et al. (2000). LOF: Identifying Density-Based Local Outliers.