org.apache.ctakes.dictionary.lookup.algorithms

Class FirstTokenPermutationImpl

java.lang.Object

org.apache.ctakes.dictionary.lookup.algorithms.FirstTokenPermutationImpl

All Implemented Interfaces:

LookupAlgorithm

public class FirstTokenPermutationImpl
extends Object
implements LookupAlgorithm

OVERVIEW: Each LookupToken is fed into a "first token" Dictionary. A hit indicates an anchor and the window around this anchor is based on context. This hit also contains all the presentations from the Dictionary where the "first token" is contained.

The window is determined by finding the largest overlapping context window annotation. Permutations of LookupTokens found within this window are used to match against the presentations found earlier. If context window annotations are not provided, a fixed window is used based on the specified max permutation level.

OPTIONAL CONTEXT: context window annotations

Author:

Mayo Clinic

Field Summary

Fields

Modifier and Type	Field and Description
static String	CTX_KEY_WINDOW_ANNOTATIONS Key value for context map.
static String	LT_KEY_USE_FOR_LOOKUP Key value for LookupToken attribute.

Constructor Summary

Constructors

Constructor and Description
FirstTokenPermutationImpl(DictionaryEngine firstTokenDictEngine, PhraseBuilder phraseBuilder, String[] textMetaFieldNames, int maxPermutationLevel) Constructor

Method Summary

Modifier and Type	Method and Description
Collection<LookupHit>	lookup(List<LookupToken> lookupTokenList, Map<String,List<LookupAnnotation>> contextMap) Lookup the given text specified via LookupToken objects.

Methods inherited from class java.lang.Object

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

Field Detail

CTX_KEY_WINDOW_ANNOTATIONS

public static final String CTX_KEY_WINDOW_ANNOTATIONS

Key value for context map. Value is expected to be a List of LookupAnnotation objects in sorted order.

See Also:

Constant Field Values

LT_KEY_USE_FOR_LOOKUP

public static final String LT_KEY_USE_FOR_LOOKUP

Key value for LookupToken attribute. Value is expected to be either TRUE or FALSE. This indicates whether to use this token for a "first token" lookup or not. This is optional.

See Also:

Constant Field Values

Constructor Detail

FirstTokenPermutationImpl

public FirstTokenPermutationImpl(DictionaryEngine firstTokenDictEngine,
                                 PhraseBuilder phraseBuilder,
                                 String[] textMetaFieldNames,
                                 int maxPermutationLevel)

Constructor

Parameters:

firstTokenDictEngine - Dictionary that is indexed against first tokens.

phraseBuilder - Builds phrases to match against Dictionary.

textMetaFieldNames - MetaFieldNames used to extract presentations.

maxPermutationLevel - Max permutation Level allowed.

Method Detail

lookup

public Collection<LookupHit> lookup(List<LookupToken> lookupTokenList,
                                    Map<String,List<LookupAnnotation>> contextMap)
                             throws Exception

Lookup the given text specified via LookupToken objects. Any hits will be returned as a collection of LookupHit objects.

Specified by:

lookup in interface LookupAlgorithm

Parameters:

lookupTokenList - List of LookupTokens, must be sorted.

contextMap - Map where key=Impl specific String object and value=List of LookupAnnotation objects

Returns:

Collection of LookupHits.

Throws:

Exception