it.cnr.isti.hpc.dexter.spot

Class Spot

java.lang.Object

it.cnr.isti.hpc.dexter.spot.Spot

All Implemented Interfaces:

Serializable

public class Spot
extends Object
implements Serializable

A spot consists of:

• the mention (i.e. the common anchor used to link the entities)
• the list of entities related to the current mention in the knowledge base
• the frequency of the mention: how many times the mention occurs in the collection (as link or simple text)
• the link frequency of the mention: how many times the mention occurs in the collection as a link to an entity
• the idf score of the mentions

The spot is not document related, but collection related.

Author:

Diego Ceccarelli, diego.ceccarelli@isti.cnr.it

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Spot.Parser A record parser for tsv encoded spots.

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	collectionSize
protected List<Entity>	entities
protected int	freq
protected double	idf
protected int	link
protected double	linkProbability
protected String	mention

Constructor Summary

Constructors

Constructor and Description
Spot(String mention) Builds a spot from a textual mention
Spot(String spot, List<Entity> entities, int link, int freq) Creates the spot, and associates the entities that can be referred by the mention, how many times the mention occurs as an anchor-text in Wikipedia and how many articles that contain the mention as anchor or simple text (i.e.

Method Summary

Methods

Modifier and Type	Method and Description
Spot	clone() Returns a copy of this object
boolean	equals(Object obj)
static Spot	fromByteArray(String text, byte[] data) Decodes a Spot from a byte representation, if the given text match the spot text encoded in the byte array.
static Spot	fromTsvLine(String text) Decodes a tab separated representation of a spot.
static int	getCollectionSize() Get the number of entities in the collection
List<Entity>	getEntities() Return the list of entities with the current mention
double	getEntityCommonness(Entity e) Computes the entity commonness for a given entity and this spot, i.e., P(e|s), the probability for an entity to be associated with this spot.
int	getFrequency() Returns the document frequency of this spot, i.e., how many wikipedia articles contain the spot as simple text or anchor text.
double	getIdf() Returns the inverse document frequency of this mention;
int	getLink() Return how many times the mention occurs in the collection as a link to an entity
double	getLinkProbability() Return the probability for the current mention to be a link
String	getMention() Returns the text of this mention;
int	hashCode()
static void	setCollectionSize(int collectionSize) Set the number of entities in the collection
void	setEntities(List<Entity> entities) Set the list of entities with the current mention
void	setFrequency(int freq) Set How many times the mention occurs in the collection.
void	setIdf(double idf) Set the inverse document frequency of the mention in the collection.
void	setLink(int link) Set how many times the mention occurs in the collection as a link to an entity
void	setLinkProbability(double probability) Set the probability for this mention to be a link;
void	setMention(String mention) Set the text of the mention
byte[]	toByteArray() Encodes this spot in a array of byte, the encode consists in: 1 byte, containing the length of the mention (it is assumed that the length n of the mention is less than 256) n bytes, containing the mention encoded in ascii 4 bytes, containing the frequency of the mention as link 4 bytes, containing the document frequency of the mention 2 x 4 x m bytes, where m is the number of entities associated with the mention, containing for each entity its unique id and its frequency (number of anchors with this text that link to the entity);
String	toString()
String	toTsv() Returns a tab separated version of the spot in a string.
protected void	updateIdf() Update the IDF using the freq and collectionSize fields
protected void	updateLinkProbability() Update the link probability using the link and freq fields

Methods inherited from class java.lang.Object

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

Field Detail

mention

protected String mention

freq

protected int freq

link

protected int link

entities

protected List<Entity> entities

linkProbability

protected double linkProbability

idf

protected double idf

collectionSize

protected static int collectionSize

Constructor Detail

Spot

public Spot(String mention)

Builds a spot from a textual mention

Parameters:

spot - The string representing the textual mention

Spot

public Spot(String spot,
    List<Entity> entities,
    int link,
    int freq)

Creates the spot, and associates the entities that can be referred by the mention, how many times the mention occurs as an anchor-text in Wikipedia and how many articles that contain the mention as anchor or simple text (i.e. document frequency of the spot).

Parameters:

spot - The string representing the spot;

entities - The list of entities that can be refered by the spot;

link - How many times the spot occurs in wikipedia as anchor text;

freq - How many articles that contain the text mention as anchor or simple text (i.e. document frequency of the spot).

Method Detail

getFrequency

public int getFrequency()

Returns the document frequency of this spot, i.e., how many wikipedia articles contain the spot as simple text or anchor text.

Returns:

The document frequency of this spot;

setFrequency

public void setFrequency(int freq)

Set How many times the mention occurs in the collection. It will consequently update the IDF value.

Parameters:

freq - How many times the mention occurs in the collection

getIdf

public double getIdf()

Returns the inverse document frequency of this mention;

Returns:

The inverse document frequency of this mention;

setIdf

public void setIdf(double idf)

Set the inverse document frequency of the mention in the collection.

Parameters:

idf - The inverse document frequency to set for this mention

getMention

public String getMention()

Returns the text of this mention;

Returns:

the text of the mention;

getLink

public int getLink()

Return how many times the mention occurs in the collection as a link to an entity

Returns:

link Times the mention occurs in the collection as a link to an entity

setLink

public void setLink(int link)

Set how many times the mention occurs in the collection as a link to an entity

Parameters:

link - Times the mention occurs in the collection as a link to an entity

getEntities

public List<Entity> getEntities()

Return the list of entities with the current mention

Returns:

the list of entities with the current mention

setEntities

public void setEntities(List<Entity> entities)

Set the list of entities with the current mention

Parameters:

entities - The list of entities with the current mention

getLinkProbability

public double getLinkProbability()

Return the probability for the current mention to be a link

Returns:

the probability for the current mention to be a link

setLinkProbability

public void setLinkProbability(double probability)

Set the probability for this mention to be a link;

Parameters:

probability - The probability of this mention to be a link

setMention

public void setMention(String mention)

Set the text of the mention

Parameters:

text - The text of the mention;

updateLinkProbability

protected void updateLinkProbability()

Update the link probability using the link and freq fields

updateIdf

protected void updateIdf()

Update the IDF using the freq and collectionSize fields

getCollectionSize

public static int getCollectionSize()

Get the number of entities in the collection

Returns:

setCollectionSize

public static void setCollectionSize(int collectionSize)

Set the number of entities in the collection

Parameters:

collectionSize - The number of entities of the collection

getEntityCommonness

public double getEntityCommonness(Entity e)

Computes the entity commonness for a given entity and this spot, i.e., P(e|s), the probability for an entity to be associated with this spot. It is computed dividing the number of times that the spot links to the entity by the frequency of spot as anchor.

Parameters:

e - The entity for which to compare the commmonness

Returns:

The

toByteArray

public byte[] toByteArray()

Encodes this spot in a array of byte, the encode consists in:

• 1 byte, containing the length of the mention (it is assumed that the length n of the mention is less than 256)
• n bytes, containing the mention encoded in ascii
• 4 bytes, containing the frequency of the mention as link
• 4 bytes, containing the document frequency of the mention
• 2 x 4 x m bytes, where m is the number of entities associated with the mention, containing for each entity its unique id and its frequency (number of anchors with this text that link to the entity);

Returns:

the encoded byte array

fromByteArray

public static Spot fromByteArray(String text,
                 byte[] data)

Decodes a Spot from a byte representation, if the given text match the spot text encoded in the byte array.

Parameters:

text - - the spot text to decode

data - - the binary rep for the spot

Returns:

A spot if the given string text matches the text of the spot encoded in data, otherwise null

See Also:

toByteArray

toTsv

public String toTsv()

Returns a tab separated version of the spot in a string. The string contains:

• the entity ids of the possible entities for this spot, encoded in esadecimal
• the frequencies of the each entity for this spot, encoded in esadecimal
• the frequency of the spot as anchor text
• the document frequency of the spot in the collection

Returns:

the tab separated representation of this spot

fromTsvLine

public static Spot fromTsvLine(String text)

Decodes a tab separated representation of a spot.

Parameters:

text -

Returns:

the spot encoded in text.

See Also:

toTsv

toString

public String toString()

Overrides:

toString in class Object

clone

public Spot clone()

Returns a copy of this object

Overrides:

clone in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object