Package opennlp.tools.namefind

Class BilouCodec

java.lang.Object

opennlp.tools.namefind.BilouCodec

All Implemented Interfaces:

SequenceCodec<String>

public class BilouCodec
extends Object
implements SequenceCodec<String>

The default SequenceCodec implementation according to the BILOU scheme.

• B: 'beginning' of a NE
• I: 'inside', the word is inside a NE
• L: 'last', the last (I) word inside a NE
• O: 'outside', the word is a regular word outside a NE
• U: 'unit', any standalone token following words outside of NE

See paper by Roth D. and Ratinov L. (2009): Design Challenges and Misconceptions in Named Entity Recognition.

See Also:

• SequenceCodec
• BioCodec

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CONTINUE
static final String	LAST
static final String	OTHER
static final String	START
static final String	UNIT

Fields inherited from interface opennlp.tools.util.SequenceCodec

DEFAULT_PREFIX

Constructor Summary

Constructors

Constructor	Description
BilouCodec()

Method Summary

Modifier and Type	Method	Description
boolean	areOutcomesCompatible(String[] outcomes)	B requires CL or L, C requires BL, L requires B, O requires any valid combo/unit, U requires none.
SequenceValidator<String>	createSequenceValidator()
Span[]	decode(List<String> c)	Decodes a sequence of objects into Span objects.
String[]	encode(Span[] names, int length)	Encodes Span objects into a sequence of objects.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

START

public static final String START

See Also:

• Constant Field Values

CONTINUE

public static final String CONTINUE

See Also:

• Constant Field Values

LAST

public static final String LAST

See Also:

• Constant Field Values

UNIT

public static final String UNIT

See Also:

• Constant Field Values

OTHER

public static final String OTHER

See Also:

• Constant Field Values

Constructor Details

BilouCodec

public BilouCodec()

Method Details

decode

public Span[] decode(List<String> c)

Description copied from interface: SequenceCodec

Decodes a sequence of objects into Span objects.

Specified by:

decode in interface SequenceCodec<String>

Parameters:

c - A list of SequenceCodec to decode.

Returns:

A Span array encapsulating the decoded elements in c.

encode

public String[] encode(Span[] names,
 int length)

Description copied from interface: SequenceCodec

Encodes Span objects into a sequence of objects.

Specified by:

encode in interface SequenceCodec<String>

Parameters:

names - A list of elements to encode.

length - The length to respect.

Returns:

An array of SequenceCodec to encode.

createSequenceValidator

public SequenceValidator<String> createSequenceValidator()

Specified by:

createSequenceValidator in interface SequenceCodec<String>

Returns:

A SequenceValidator which can validate a sequence of outcomes.

areOutcomesCompatible

public boolean areOutcomesCompatible(String[] outcomes)

B requires CL or L, C requires BL, L requires B, O requires any valid combo/unit, U requires none.

Specified by:

areOutcomesCompatible in interface SequenceCodec<String>

Parameters:

outcomes - All potential model outcomes check.

Returns:

true, if model outcomes are compatible, false otherwise.