org.apache.mahout.common.distance
Class ManhattanDistanceMeasure

java.lang.Object
  extended by org.apache.mahout.common.distance.ManhattanDistanceMeasure
All Implemented Interfaces:
DistanceMeasure, Parametered

public class ManhattanDistanceMeasure
extends Object
implements DistanceMeasure

This class implements a "manhattan distance" metric by summing the absolute values of the difference between each coordinate


Nested Class Summary
 
Nested classes/interfaces inherited from interface org.apache.mahout.common.parameters.Parametered
Parametered.ParameteredGeneralizations
 
Field Summary
 
Fields inherited from interface org.apache.mahout.common.parameters.Parametered
log
 
Constructor Summary
ManhattanDistanceMeasure()
           
 
Method Summary
 void configure(org.apache.hadoop.conf.Configuration job)
           
 void createParameters(String prefix, org.apache.hadoop.conf.Configuration jobConf)
          EXPERT: consumers should never have to call this method.
static double distance(double[] p1, double[] p2)
           
 double distance(double centroidLengthSquare, Vector centroid, Vector v)
          Optimized version of distance metric for sparse vectors.
 double distance(Vector v1, Vector v2)
          Returns the distance metric applied to the arguments
 Collection<Parameter<?>> getParameters()
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ManhattanDistanceMeasure

public ManhattanDistanceMeasure()
Method Detail

distance

public static double distance(double[] p1,
                              double[] p2)

configure

public void configure(org.apache.hadoop.conf.Configuration job)
Specified by:
configure in interface Parametered

getParameters

public Collection<Parameter<?>> getParameters()
Specified by:
getParameters in interface Parametered

createParameters

public void createParameters(String prefix,
                             org.apache.hadoop.conf.Configuration jobConf)
Description copied from interface: Parametered
EXPERT: consumers should never have to call this method. It would be friendly visible to Parametered.ParameteredGeneralizations if java supported it. Calling this method should create a new list of parameters and is called

Specified by:
createParameters in interface Parametered
Parameters:
prefix - ends with a dot if not empty.
jobConf - configuration used for retrieving values
See Also:
invoking method, invoking method

distance

public double distance(Vector v1,
                       Vector v2)
Description copied from interface: DistanceMeasure
Returns the distance metric applied to the arguments

Specified by:
distance in interface DistanceMeasure
Parameters:
v1 - a Vector defining a multidimensional point in some feature space
v2 - a Vector defining a multidimensional point in some feature space
Returns:
a scalar doubles of the distance

distance

public double distance(double centroidLengthSquare,
                       Vector centroid,
                       Vector v)
Description copied from interface: DistanceMeasure
Optimized version of distance metric for sparse vectors. This distance computation requires operations proportional to the number of non-zero elements in the vector instead of the cardinality of the vector.

Specified by:
distance in interface DistanceMeasure
Parameters:
centroidLengthSquare - Square of the length of centroid
centroid - Centroid vector


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