org.apache.solr.ltr.feature

Class Feature

java.lang.Object

org.apache.lucene.search.Query

org.apache.solr.ltr.feature.Feature

All Implemented Interfaces:

Accountable

Direct Known Subclasses:

FieldLengthFeature, FieldValueFeature, OriginalScoreFeature, SolrFeature, ValueFeature

public abstract class Feature
extends Query
implements Accountable

A recipe for computing a feature. Subclass this for specialized feature calculations.

A feature consists of

• a name as the identifier
• parameters to represent the specific feature

Example configuration (snippet):

{
   "class" : "...",
   "name" : "myFeature",
   "params" : {
       ...
   }
}

Feature is an abstract class and concrete classes should implement the validate() function, and must implement the paramsToMap() and createWeight() methods.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	Feature.FeatureWeight Weight for a feature

Field Summary

Fields

Modifier and Type	Field and Description
protected String	name

Constructor Summary

Constructors

Constructor and Description
Feature(String name, Map<String,Object> params)

Method Summary

Modifier and Type	Method and Description
abstract Feature.FeatureWeight	createWeight(IndexSearcher searcher, boolean needsScores, SolrQueryRequest request, Query originalQuery, Map<String,String[]> efi)
protected LinkedHashMap<String,Object>	defaultParamsToMap()
boolean	equals(Object o)
float	getDefaultValue()
int	getIndex()
static Feature	getInstance(SolrResourceLoader solrResourceLoader, String className, String name, Map<String,Object> params)
String	getName()
int	hashCode()
abstract LinkedHashMap<String,Object>	paramsToMap()
long	ramBytesUsed()
void	setDefaultValue(Object obj)
void	setIndex(int index)
String	toString(String field)
protected abstract void	validate() As part of creation of a feature instance, this function confirms that the feature parameters are valid.
void	visit(QueryVisitor visitor)

Methods inherited from class org.apache.lucene.search.Query

classHash, createWeight, rewrite, sameClassAs, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.lucene.util.Accountable

getChildResources

Field Detail

name

protected final String name

Constructor Detail

Feature

public Feature(String name,
               Map<String,Object> params)

Method Detail

getInstance

public static Feature getInstance(SolrResourceLoader solrResourceLoader,
                                  String className,
                                  String name,
                                  Map<String,Object> params)

validate

protected abstract void validate()
                          throws FeatureException

As part of creation of a feature instance, this function confirms that the feature parameters are valid.

Throws:

FeatureException - Feature Exception

toString

public String toString(String field)

Specified by:

toString in class Query

createWeight

public abstract Feature.FeatureWeight createWeight(IndexSearcher searcher,
                                                   boolean needsScores,
                                                   SolrQueryRequest request,
                                                   Query originalQuery,
                                                   Map<String,String[]> efi)
                                            throws IOException

Throws:

IOException

getDefaultValue

public float getDefaultValue()

setDefaultValue

public void setDefaultValue(Object obj)

hashCode

public int hashCode()

Specified by:

hashCode in class Query

equals

public boolean equals(Object o)

Specified by:

equals in class Query

ramBytesUsed

public long ramBytesUsed()

Specified by:

ramBytesUsed in interface Accountable

visit

public void visit(QueryVisitor visitor)

Overrides:

visit in class Query

getName

public String getName()

Returns:

the name

getIndex

public int getIndex()

Returns:

the id

setIndex

public void setIndex(int index)

Parameters:

index - Unique ID for this feature. Similar to feature name, except it can be used to directly access the feature in the global list of features.

paramsToMap

public abstract LinkedHashMap<String,Object> paramsToMap()

defaultParamsToMap

protected LinkedHashMap<String,Object> defaultParamsToMap()