PhraseScoreModifier (Terrier 4.0 API)

java.lang.Object
- org.terrier.matching.dsms.PhraseScoreModifier

All Implemented Interfaces:

Cloneable, DocumentScoreModifier
```
public class PhraseScoreModifier
extends Object
implements DocumentScoreModifier
```
This is the class performs the re-scoring for a phrase queries. If the block distance (window size) is greater than 1 then ProximityIterablePosting is used, else PhraseIterablePosting is used.

Author:

Richard McCreadie

Field Summary

Fields
Modifier and Type	Field and Description
`protected int`	`blockDistance` The maximum distance, in blocks, that is allowed between the phrase terms.
`protected static org.apache.log4j.Logger`	`logger` the logger for this class
`protected List<Query>`	`phraseTerms` A list of the strings of the phrase terms.
`protected boolean`	`required` Indicates whether the phrase should appear in the retrieved documents, or not.

Constructor Summary

Constructors
Constructor and Description
`PhraseScoreModifier(List<Query> pTerms)` Constructs a phrase score modifier for a given set of query terms.
`PhraseScoreModifier(List<Query> pTerms, boolean r)` Constructs a phrase score modifier for a given set of query terms.
`PhraseScoreModifier(List<Query> pTerms, boolean r, int bDist)` Constructs a phrase score modifier for a given set of query terms, whether they are required to appear in a document, and the allowed distance between the phrase terms.
`PhraseScoreModifier(List<Query> pTerms, int bDist)` Constructs a phrase score modifier for a given set of query terms and the allowed distance between them.

Method Summary

Methods
Modifier and Type	Method and Description
`Object`	`clone()` Clones this DSM.
`String`	`getName()` Returns the name of the document score modifier.
`boolean`	`modifyScores(Index index, MatchingQueryTerms terms, ResultSet resultSet)` Modifies the scores of the documents for a given query.

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - logger
```
protected static final org.apache.log4j.Logger logger
```
    the logger for this class
  - blockDistance
```
protected int blockDistance
```
    The maximum distance, in blocks, that is allowed between the phrase terms. The default value of one corresponds to phrase search, while any higher value enables proximity search.
  - phraseTerms
```
protected List<Query> phraseTerms
```
    A list of the strings of the phrase terms.
  - required
```
protected boolean required
```
    Indicates whether the phrase should appear in the retrieved documents, or not. The default value is true.
- Constructor Detail
  - PhraseScoreModifier
```
public PhraseScoreModifier(List<Query> pTerms)
```
    Constructs a phrase score modifier for a given set of query terms.
    
    Parameters:
    pTerms - ArrayList the terms that make up the query.
  - PhraseScoreModifier
```
public PhraseScoreModifier(List<Query> pTerms,
                   int bDist)
```
    Constructs a phrase score modifier for a given set of query terms and the allowed distance between them.
    
    Parameters:
    pTerms - ArrayList the terms that make up the query.
    bDist - int the allowed distance between phrase terms.
  - PhraseScoreModifier
```
public PhraseScoreModifier(List<Query> pTerms,
                   boolean r)
```
    Constructs a phrase score modifier for a given set of query terms.
    
    Parameters:
    pTerms - ArrayList the terms that make up the query.
    r - boolean indicates whether the phrase is required.
  - PhraseScoreModifier
```
public PhraseScoreModifier(List<Query> pTerms,
                   boolean r,
                   int bDist)
```
    Constructs a phrase score modifier for a given set of query terms, whether they are required to appear in a document, and the allowed distance between the phrase terms.
    
    Parameters:
    pTerms - ArrayList the terms that make up the query.
    r - boolean indicates whether the phrase is required.
    bDist - int the allowed distance between the phrase terms.
- Method Detail
  - modifyScores
```
public boolean modifyScores(Index index,
                   MatchingQueryTerms terms,
                   ResultSet resultSet)
```
    Description copied from interface: DocumentScoreModifier
    
    Modifies the scores of the documents for a given query. This returns a boolean that allows the Matching class to determine if the scores of the documents have actually been altered. This is because the resultset has to be resorted after each one.
    
    Specified by:
    
    modifyScores in interface DocumentScoreModifier
    
    Parameters:
    index - Index the data structures used for retrieval.
    terms - TermTreeNodes[] the query terms
    resultSet - ResultSet the current set of results.
    
    Returns:
    true if any scores have been altered
  - getName
```
public String getName()
```
    Description copied from interface: DocumentScoreModifier
    
    Returns the name of the document score modifier.
    
    Specified by:
    
    getName in interface DocumentScoreModifier
    
    Returns:
    String the name of the document score modifier.
  - clone
```
public Object clone()
```
    Clones this DSM. Note that phraseTerms is shallow copied, because Strings are immutable
    
    Specified by:
    
    clone in interface DocumentScoreModifier
    
    Overrides:
    
    clone in class Object

Class PhraseScoreModifier

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

logger

blockDistance

phraseTerms

required

Constructor Detail

PhraseScoreModifier

PhraseScoreModifier

PhraseScoreModifier

PhraseScoreModifier

Method Detail

modifyScores

getName

clone