org.terrier.structures

Class BasicLexiconEntry

java.lang.Object

org.terrier.structures.LexiconEntry

org.terrier.structures.BasicLexiconEntry

All Implemented Interfaces:

Serializable, org.apache.hadoop.io.Writable, BitFilePosition, BitIndexPointer, EntryStatistics, Pointer

Direct Known Subclasses:

BlockFieldLexiconEntry, BlockLexiconEntry, FieldLexiconEntry

public class BasicLexiconEntry
extends LexiconEntry
implements BitIndexPointer

Contains all the information about one entry in the Lexicon. Created to make thread-safe lookups in the Lexicon easier.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BasicLexiconEntry.Factory Factory for creating LexiconEntry objects

Field Summary

Fields

Modifier and Type	Field and Description
int	n_t the number of document that this entry occurs in
byte	startBitOffset the start bit offset of the entry in the inverted index
long	startOffset the start offset of the entry in the inverted index
int	termId the termid of this entry
int	TF the total number of occurrences of the term in the index

Fields inherited from interface org.terrier.structures.BitIndexPointer

BIT_MASK, FILE_SHIFT, MAX_FILE_ID

Constructor Summary

Constructors

Constructor and Description
BasicLexiconEntry() Create an empty LexiconEntry
BasicLexiconEntry(int tid, int _n_t, int _TF) Create a lexicon entry with the following information.
BasicLexiconEntry(int tid, int _n_t, int _TF, byte fileId, BitFilePosition offset) Create a lexicon entry with the following information.
BasicLexiconEntry(int tid, int _n_t, int _TF, byte fileId, long _startOffset, byte _startBitOffset) Create a lexicon entry with the following information.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(EntryStatistics le) increment this lexicon entry by another
int	getDocumentFrequency() The number of documents that the entry (term) occurred in
byte	getFileNumber() Returns the file number: 0-32
int	getFrequency() The frequency (total number of occurrences) of the entry (term).
int	getNumberOfEntries() Returns number of "things" that this pointer refers to
long	getOffset() Return the offset
byte	getOffsetBits() Return the offset bits
int	getTermId() The id of the term
String	pointerToString() Returns a textual representation of the pointer alone
void	readFields(DataInput in)
void	setBitIndexPointer(BitIndexPointer pointer) Update this pointer to reflect the same values as the specified pointer
void	setFileNumber(byte fileId) Set the file number
void	setNumberOfEntries(int n) Set the number of "things that the pointer refers to
void	setOffset(BitFilePosition pos) Set the offset
void	setOffset(long bytes, byte bits) Set the offset in bytes and bits
void	setPointer(Pointer p) Sets the pointer within this object to that represented by the specified pointer
void	setStatistics(int _n_t, int _TF) Set the term statistics, in particular, the number of documents that this term appears in and the total number of occurrences of the term.
void	setTermId(int newTermId) Sets the ID for this term
void	subtract(EntryStatistics le) alter this lexicon entry to subtract another lexicon entry
String	toString() returns a string representation of this lexicon entry
void	write(DataOutput out)

Methods inherited from class org.terrier.structures.LexiconEntry

equals, getWritableEntryStatistics, hashCode

Methods inherited from class java.lang.Object

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

Field Detail

termId

public int termId

the termid of this entry

n_t

public int n_t

the number of document that this entry occurs in

TF

public int TF

the total number of occurrences of the term in the index

startOffset

public long startOffset

the start offset of the entry in the inverted index

startBitOffset

public byte startBitOffset

the start bit offset of the entry in the inverted index

Constructor Detail

BasicLexiconEntry

public BasicLexiconEntry()

Create an empty LexiconEntry

BasicLexiconEntry

public BasicLexiconEntry(int tid,
                 int _n_t,
                 int _TF)

Create a lexicon entry with the following information.

Parameters:

tid - the term id

_n_t - the number of documents the term occurs in (document frequency)

_TF - the total count of therm t in the collection

BasicLexiconEntry

public BasicLexiconEntry(int tid,
                 int _n_t,
                 int _TF,
                 byte fileId,
                 long _startOffset,
                 byte _startBitOffset)

Create a lexicon entry with the following information.

Parameters:

tid -

_n_t -

_TF -

fileId -

_startOffset -

_startBitOffset -

BasicLexiconEntry

public BasicLexiconEntry(int tid,
                 int _n_t,
                 int _TF,
                 byte fileId,
                 BitFilePosition offset)

Create a lexicon entry with the following information.

Parameters:

tid -

_n_t -

_TF -

fileId -

offset -

Method Detail

setStatistics

public void setStatistics(int _n_t,
                 int _TF)

Set the term statistics, in particular, the number of documents that this term appears in and the total number of occurrences of the term.

Specified by:

setStatistics in class LexiconEntry

add

public void add(EntryStatistics le)

increment this lexicon entry by another

Specified by:

add in interface EntryStatistics

subtract

public void subtract(EntryStatistics le)

alter this lexicon entry to subtract another lexicon entry

Specified by:

subtract in interface EntryStatistics

toString

public String toString()

returns a string representation of this lexicon entry

Overrides:

toString in class LexiconEntry

getDocumentFrequency

public int getDocumentFrequency()

The number of documents that the entry (term) occurred in

Specified by:

getDocumentFrequency in interface EntryStatistics

getFrequency

public int getFrequency()

The frequency (total number of occurrences) of the entry (term).

Specified by:

getFrequency in interface EntryStatistics

getTermId

public int getTermId()

The id of the term

Specified by:

getTermId in interface EntryStatistics

getNumberOfEntries

public int getNumberOfEntries()

Returns number of "things" that this pointer refers to

Specified by:

getNumberOfEntries in interface Pointer

Overrides:

getNumberOfEntries in class LexiconEntry

getOffsetBits

public byte getOffsetBits()

Return the offset bits

Specified by:

getOffsetBits in interface BitFilePosition

getOffset

public long getOffset()

Return the offset

Specified by:

getOffset in interface BitFilePosition

getFileNumber

public byte getFileNumber()

Returns the file number: 0-32

Specified by:

getFileNumber in interface BitIndexPointer

setFileNumber

public void setFileNumber(byte fileId)

Set the file number

Specified by:

setFileNumber in interface BitIndexPointer

setTermId

public void setTermId(int newTermId)

Sets the ID for this term

Specified by:

setTermId in class LexiconEntry

setOffset

public void setOffset(long bytes,
             byte bits)

Set the offset in bytes and bits

Specified by:

setOffset in interface BitFilePosition

setBitIndexPointer

public void setBitIndexPointer(BitIndexPointer pointer)

Update this pointer to reflect the same values as the specified pointer

Specified by:

setBitIndexPointer in interface BitIndexPointer

Parameters:

pointer - - pointer to use to set the offset, bit offset and file Id parameters.

setOffset

public void setOffset(BitFilePosition pos)

Set the offset

Specified by:

setOffset in interface BitFilePosition

readFields

public void readFields(DataInput in)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Throws:

IOException

write

public void write(DataOutput out)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Throws:

IOException

setNumberOfEntries

public void setNumberOfEntries(int n)

Set the number of "things that the pointer refers to

Specified by:

setNumberOfEntries in interface Pointer

Overrides:

setNumberOfEntries in class LexiconEntry

pointerToString

public String pointerToString()

Returns a textual representation of the pointer alone

Specified by:

pointerToString in interface Pointer

Overrides:

pointerToString in class LexiconEntry

setPointer

public void setPointer(Pointer p)

Sets the pointer within this object to that represented by the specified pointer

Specified by:

setPointer in interface Pointer

Overrides:

setPointer in class LexiconEntry

Parameters:

p - other pointer to update the pointer in this object