org.locationtech.geowave.analytic.mapreduce.kmeans

Class KSamplerMapReduce

java.lang.Object

org.locationtech.geowave.analytic.mapreduce.kmeans.KSamplerMapReduce

public class KSamplerMapReduce
extends Object

Samples a random 'k' number of features from a population of geospatial features PER GROUP. Outputs the samples in SimpleFeatures. Sampling is achieved by picking the top ranked input objects. Rank is determined by a sample function implementing SamplingRankFunction.

The input features should have a groupID set if they intend to be sampled by group.

Keys are partitioned by the group ID in an attempt to process each group in a separate reducer.

Sampled features are written to as a new SimpleFeature to a data store. The SimpleFeature contains attributes:

name - data id of the sampled point

weight - can be anything including the sum of all assigned feature distances

geometry - geometry of the sampled features

count - to hold the number of assigned features

groupID - the assigned group ID to the input objects

Properties:

"KSamplerMapReduce.Sample.SampleSize" - number of input objects to sample. defaults to 1.

"KSamplerMapReduce.Sample.DataTypeId" - Id of the data type to store the k samples - defaults to "centroids"

"KSamplerMapReduce.Centroid.ExtractorClass" - extracts a centroid from an item. This parameter allows customization of determining one or more representative centroids for a geometry.

"KSamplerMapReduce.Sample.IndexId" - The Index ID used for output simple features.

"KSamplerMapReduce.Sample.SampleRankFunction" - An implementation of SamplingRankFunction used to rank the input object.

"KSamplerMapReduce.Centroid.ZoomLevel" - Sets an attribute on the sampled objects recording a zoom level used in the sampling process. The interpretation of the attribute is not specified or assumed.

"KSamplerMapReduce.Global.BatchId" ->the id of the batch; defaults to current time in millis (for range comparisons)

"KSamplerMapReduce.Centroid.WrapperFactoryClass" -> AnalyticItemWrapperFactory to extract non-geometric dimensions

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	KSamplerMapReduce.SampleKeyPartitioner
static class	KSamplerMapReduce.SampleMap<T>
static class	KSamplerMapReduce.SampleReducer<T>

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.slf4j.Logger	LOGGER

Constructor Summary

Constructors

Constructor and Description
KSamplerMapReduce()

Method Summary

Methods inherited from class java.lang.Object

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

Field Detail

LOGGER

protected static final org.slf4j.Logger LOGGER

Constructor Detail

KSamplerMapReduce

public KSamplerMapReduce()