In Mahout, there are different distance measure classes defined in the org.apache.mahout.common.distance package. Among them are SquaredEuclideanDistanceMeasure, EuclideanDistanceMeasure, CosineDistanceMeasure, MahalanobisDistanceMeasure, ManhattanDistanceMeasure. These distance classes implements the DistanceMeasure interface.

There is also support for weighted version of DistanceMeasure eg. WeightedEuclideanDistanceMeasure and WeightedManhattanDistanceMeasure. Both extends the abstract class WeightedDistanceMeasure.

DistanceMeasure Mahout

WeightedDistanceMeasure