CollectionResultSet (Terrier Information Retrieval Platform 4.1 API)

java.lang.Object
- org.terrier.matching.CollectionResultSet

All Implemented Interfaces:

Serializable, ResultSet

Direct Known Subclasses:

QueryResultSet
```
public class CollectionResultSet
extends Object
implements ResultSet, Serializable
```
This class implements the interface ResultSet and models the set of all documents in the collection. It encapsulates two arrays, one for the docids and one for the scores. It has also the occurrences matrix which counts how many query terms appear in each of the retrieved documents. The metadata related methods are empty.
This class is only used internally by the Matching class and the classes that extent it, because the arrays for the docids and scores contain one entry for each document in the collection. Therefore, the instantiation of an object of this class can be expensive. Access to the retrieved documents is enabled by using the method GetResultSet that returns a cropped result set.

Author:

Vassilis plachouras

See Also:
Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected boolean`	`arraysInitialised` A static boolean flag indicating whether the arrays of docids and scores have been initialized (memory allocated for them) or not.
`protected int[]`	`docids` The array that stores the document ids.
`protected int`	`exactResultSize` The number of retrieved documents.
`protected Lock`	`lock` A lock for enabling access of the result set by different threads
`protected short[]`	`occurrences` The occurrences of the query terms in a document.
`protected int`	`resultSize` The number of documents that have been ranked and sorted according to their scores.
`protected double[]`	`scores` An array holding the scores of documents in the collection.
`protected int`	`statusCode` A status code for the result set.

Constructor Summary

Constructors
Constructor and Description
`CollectionResultSet(int numberOfDocuments)` A default constructor for the result set with a given number of documents.
`CollectionResultSet(int[] _docids, double[] _scores, short[] _occurrences)` Construct a resultset from the following components
`CollectionResultSet(ResultSet resultSet)` A default constructor for the result set with a given instance of the result set.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addMetaItem(String name, int docid, String value)` Empty method.
`void`	`addMetaItems(String name, String[] values)` Empty method.
`int[]`	`getDocids()` Returns the documents ids after retrieval
`int`	`getExactResultSize()` Returns the exact size of the result set.
`Lock`	`getLock()` Returns the lock for enabling the modification of the result set by more than one threads.
`String`	`getMetaItem(String name, int docid)` Empty method.
`String[]`	`getMetaItems(String name)` Empty method.
`String[]`	`getMetaKeys()` Returns the names of the meta keys which this resultset has
`short[]`	`getOccurrences()` Returns the occurrences array.
`ResultSet`	`getResultSet(int[] positions)` Extracts a subset of the resultset given by the list parameter, which contains a list of positions in the resultset that should be saved.
`ResultSet`	`getResultSet(int start, int length)` Crops the existing result file and extracts a subset from the given starting point to the ending point.
`int`	`getResultSize()` Returns the effective size of the result set.
`double[]`	`getScores()` Returns the documents scores after retrieval
`int`	`getStatusCode()` Returns the status code for the current result set.
`boolean`	`hasMetaItems(String name)` Returns true if the resultset already has a set of metaitems with the specified name.
`void`	`initialise()` Initialises the arrays prior of retrieval.
`void`	`initialise(double[] scs)` Initialises the result set with the given scores.
`void`	`setExactResultSize(int newExactResultSize)` Sets the exact size of the result set, that is the number of documents that would be retrieved, if the result set was not truncated.
`void`	`setResultSize(int newResultSize)` Sets the effective size of the result set, that is the number of documents to be sorted after retrieval.
`void`	`setStatusCode(int _statusCode)` Sets the status code for the current result set.
`void`	`sort()` Sorts all documents in this resultset by descending score
`void`	`sort(int topDocs)` Sorts the top `topDocs` document in this resultset be first.

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

- Field Detail
  - docids
```
protected int[] docids
```
    The array that stores the document ids.
  - scores
```
protected double[] scores
```
    An array holding the scores of documents in the collection.
  - occurrences
```
protected short[] occurrences
```
    The occurrences of the query terms in a document. This allows to use Boolean operators and filter documents. If the i-th query term appears in the j-th document, then the i-th bit of occurrences[j] is set, otherwise it is zero. Using a 2-byte long integer allows to check for the occurence of up to 16 query terms.
  - arraysInitialised
```
protected boolean arraysInitialised
```
    A static boolean flag indicating whether the arrays of docids and scores have been initialized (memory allocated for them) or not.
  - resultSize
```
protected int resultSize
```
    The number of documents that have been ranked and sorted according to their scores.
  - exactResultSize
```
protected int exactResultSize
```
    The number of retrieved documents. This may be higher that <tt>resultSize<tt>, and corresponds to the number of documents that contain at least one query term.
  - lock
```
protected Lock lock
```
    A lock for enabling access of the result set by different threads
  - statusCode
```
protected int statusCode
```
    A status code for the result set.
- Constructor Detail
  - CollectionResultSet
```
public CollectionResultSet(int[] _docids,
                   double[] _scores,
                   short[] _occurrences)
```
    Construct a resultset from the following components
  - CollectionResultSet
```
public CollectionResultSet(int numberOfDocuments)
```
    A default constructor for the result set with a given number of documents.
    
    Parameters:
    numberOfDocuments - the number of documents contained in the result set.
  - CollectionResultSet
```
public CollectionResultSet(ResultSet resultSet)
```
    A default constructor for the result set with a given instance of the result set. The constructor creates a clone of the given result set.
    
    Parameters:
    resultSet - The given result set.
- Method Detail
  - getLock
```
public Lock getLock()
```
    Returns the lock for enabling the modification of the result set by more than one threads.
    
    Specified by:
    
    getLock in interface ResultSet
    
    Returns:
    the lock.
  - getStatusCode
```
public int getStatusCode()
```
    Returns the status code for the current result set.
    
    Specified by:
    
    getStatusCode in interface ResultSet
    
    Returns:
    a integer status code. 0 stands success. 1 stands for empty result set. 2 stands for wrong setting of start/end parameters. 3 stands for query timeout. The values assigned to the status codes are increasing accordingly to the severity of the status.
  - setStatusCode
```
public void setStatusCode(int _statusCode)
```
    Sets the status code for the current result set.
    
    Specified by:
    
    setStatusCode in interface ResultSet
    
    Parameters:
    _statusCode - - the code to return to the user
  - getDocids
```
public int[] getDocids()
```
    Returns the documents ids after retrieval
    
    Specified by:
    
    getDocids in interface ResultSet
    
    Returns:
    the docids
  - getResultSize
```
public int getResultSize()
```
    Returns the effective size of the result set.
    
    Specified by:
    
    getResultSize in interface ResultSet
    
    Returns:
    int the effective size of the result set
  - getOccurrences
```
public short[] getOccurrences()
```
    Returns the occurrences array.
    
    Specified by:
    
    getOccurrences in interface ResultSet
    
    Returns:
    int[] the array the occurrences array.
  - getExactResultSize
```
public int getExactResultSize()
```
    Returns the exact size of the result set.
    
    Specified by:
    
    getExactResultSize in interface ResultSet
    
    Returns:
    int the exact size of the result set
  - getScores
```
public double[] getScores()
```
    Returns the documents scores after retrieval
    
    Specified by:
    
    getScores in interface ResultSet
    
    Returns:
    score list in same order as docids array
  - initialise
```
public void initialise()
```
    Initialises the arrays prior of retrieval.
    
    Specified by:
    
    initialise in interface ResultSet
  - initialise
```
public void initialise(double[] scs)
```
    Initialises the result set with the given scores. If the length of the given array is different than the length of the internal arrays, then we re-allocate memory and create the arrays.
    
    Specified by:
    
    initialise in interface ResultSet
    
    Parameters:
    scs - double[] the scores to initiliase the result set with.
  - setResultSize
```
public void setResultSize(int newResultSize)
```
    Sets the effective size of the result set, that is the number of documents to be sorted after retrieval.
    
    Specified by:
    
    setResultSize in interface ResultSet
    
    Parameters:
    newResultSize - int the effective size of the result set.
  - setExactResultSize
```
public void setExactResultSize(int newExactResultSize)
```
    Sets the exact size of the result set, that is the number of documents that would be retrieved, if the result set was not truncated.
    
    Specified by:
    
    setExactResultSize in interface ResultSet
    
    Parameters:
    newExactResultSize - int the effective size of the result set.
  - addMetaItem
```
public void addMetaItem(String name,
               int docid,
               String value)
```
    Empty method.
    
    Specified by:
    
    addMetaItem in interface ResultSet
    
    Parameters:
    name - the name of the metadata type. For example, it can be the url for adding the URLs of documents.
    docid - the document identifier of the document.
    value - the metadata value.
  - addMetaItems
```
public void addMetaItems(String name,
                String[] values)
```
    Empty method.
    
    Specified by:
    
    addMetaItems in interface ResultSet
    
    Parameters:
    name - the name of the metadata type. For example, it can be the url for adding the URLs of documents.
    values - the metadata values.
  - getMetaItem
```
public String getMetaItem(String name,
                 int docid)
```
    Empty method.
    
    Specified by:
    
    getMetaItem in interface ResultSet
    
    Parameters:
    name - the name of the metadata type.
    docid - the document identifier of the document.
    
    Returns:
    a string with the metadata information, or null of the metadata is not available.
  - getMetaItems
```
public String[] getMetaItems(String name)
```
    Empty method.
    
    Specified by:
    
    getMetaItems in interface ResultSet
    
    Parameters:
    name - the name of the metadata type.
    
    Returns:
    an array of strings with the metadata information, or null of the metadata is not available.
  - getResultSet
```
public ResultSet getResultSet(int start,
                     int length)
```
    Crops the existing result file and extracts a subset from the given starting point to the ending point.
    
    Specified by:
    
    getResultSet in interface ResultSet
    
    Parameters:
    start - the beginning of the subset.
    length - the end of the subset.
    
    Returns:
    ResultSet a subset of the current result set.
  - getResultSet
```
public ResultSet getResultSet(int[] positions)
```
    Extracts a subset of the resultset given by the list parameter, which contains a list of positions in the resultset that should be saved.
    NB:The metadata hashtable is NOT reduced.
    
    Specified by:
    
    getResultSet in interface ResultSet
    
    Parameters:
    positions - int[] the list of elements in the current list that should be kept.
    
    Returns:
    a subset of the current result set specified by the list.
  - hasMetaItems
```
public boolean hasMetaItems(String name)
```
    Returns true if the resultset already has a set of metaitems with the specified name.
    
    Specified by:
    
    hasMetaItems in interface ResultSet
    
    Parameters:
    name - of the desired metaitem set
    
    Returns:
    true if the set exists.
  - getMetaKeys
```
public String[] getMetaKeys()
```
    Returns the names of the meta keys which this resultset has
    
    Specified by:
    
    getMetaKeys in interface ResultSet
    
    Returns:
    the list of key names
  - sort
```
public void sort()
```
    Description copied from interface: ResultSet
    
    Sorts all documents in this resultset by descending score
    
    Specified by:
    
    sort in interface ResultSet
  - sort
```
public void sort(int topDocs)
```
    Description copied from interface: ResultSet
    
    Sorts the top topDocs document in this resultset be first. The order of the remaining documents is undefined.
    
    Specified by:
    
    sort in interface ResultSet
    
    Parameters:
    topDocs - number of documents to top-rank

Class CollectionResultSet

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

docids

scores

occurrences

arraysInitialised

resultSize

exactResultSize

lock

statusCode

Constructor Detail

CollectionResultSet

CollectionResultSet

CollectionResultSet

Method Detail

getLock

getStatusCode

setStatusCode

getDocids

getResultSize

getOccurrences

getExactResultSize

getScores

initialise

initialise

setResultSize

setExactResultSize

addMetaItem

addMetaItems

getMetaItem

getMetaItems

getResultSet

getResultSet

hasMetaItems

getMetaKeys

sort

sort