Description
JCasUtil (and its equivalent CASUtil) have two very useful methods:
- selectSingle(JCas jCas, Class<T> type), retrieving all T type annotations from the CAS, making sure only one exists, and returning it
- selectCovered(JCas jCas, final Class<T> type, AnnotationFS coveringAnnotation), retrieving all T type annotations from the CAS, that exist in the span defined by the covering annotation.
My request is to add a selectCoveredSingle method (I already implemented and tested, written below). It would retrieve all T type annotation in the span of the covering annotation, make sure there is only one, and return it.
The uses for such a method would be really common, as this assists in performing something very basic in UIMA - once you have some annotation, you want to retrieve other information on it, and if it is a small unit, then you know in advance that many types of information should only appear once for that annotation. Otherwise, it's an error.
For instance, say I have linguistically annotated text, and I hold some intersting annotation of a Token. Then I want to find out what is its Part Of Speech. Then I would simply call: selectCoveredSingle(jcas, PartOfSpeech.class, token), and get exactly one PartOfSpeech annotation as I expected. If there is none or more then one, an exception is thrown.
One could also use a method like selectCoveredSingleOptional (not implemented yet), that does exactly the same, but returns null when no such annotation exists, instead of throwing an exception. This makes sense when a token can have some optional attribute. In linguistics, it could be when a Token may be a NamedEntity, but not necessarily.
the implementation is made out of two methods - the first should be in JCasUtil, the second should be in CASUtil.
===
Implementation:
===
/**
- Get the annotation of the given annotation type constrained by a 'covering' annotation.
- Iterates over all annotations of the given type to find the covered annotations.
- Does not use subiterators.
* - @param <T>
- the JCas type.
- @param jCas
- a JCas containing the annotation.
- @param type
- a UIMA type.
- @param coveringAnnotation
- the covering annotation.
- @return the single instance of the given type.
- @throws IllegalArgumentException if not exactly one instance if the given type is present
- under the covering annotation.
- @see Subiterator
- @author Ofer Bronstein
- @since April 2014
*/
@SuppressWarnings("unchecked")
public static <T extends Annotation> T selectCoveredSingle(JCas jCas, final Class<T> type,
AnnotationFS coveringAnnotation) { return (T) selectCoveredSingle(jCas.getCas(), JCasUtil.getType(jCas, type), coveringAnnotation); }
/**
- Get the annotation of the given annotation type constrained by a 'covering' annotation.
- Iterates over all annotations of the given type to find the covered annotations.
- Does not use subiterators.
* - @param cas
- a cas containing the annotation.
- @param type
- a UIMA type.
- @param coveringAnnotation
- the covering annotation.
- @return the single instance of the given type.
- @throws IllegalArgumentException if not exactly one instance if the given type is present
- under the covering annotation.
- @see Subiterator
- @author Ofer Bronstein
- @since April 2014
*/
public static AnnotationFS selectCoveredSingle(CAS cas, Type type,
AnnotationFS coveringAnnotation) {
List<AnnotationFS> annotations = CasUtil.selectCovered(cas, type, coveringAnnotation);
if (annotations.isEmpty())
{ throw new IllegalArgumentException("CAS does not contain any [" + type.getName() + "]"); }if (annotations.size() > 1)
{ throw new IllegalArgumentException("CAS contains more than one [" + type.getName() + "]"); } return annotations.get(0);
}
Attachments
Issue Links
- relates to
-
UIMA-5115 uv3 select() api for iterators and streams over CAS contents
-
- Resolved
-
