Armin,
Our team does this with an annotation type designed to store feature vectors
for Machine Learning applications. In this case we use a StringArray feature
for the keys and a StringArray feature for the values. The StringArrays are
pulled from a HashMap<String, String> vector variable and inserted into the
features with the following code:
int size = vector.size();
StringArray keys = new StringArray(jcas, size);
StringArray values = new StringArray(jcas, size);
keys.copyFromArray(vector.keySet().toArray(new String[size]), 0, 0, size);
values.copyFromArray(vector.values().toArray(new String[size]), 0, 0, size);
Retrieving the values is fairly straightforward. If you are using a static
annotation type it can be as simple as:
StringArray keys = vector.getKeysArray();
If you parameterize our annotation type in the annotator you can use the name
of the feature to get a Feature object reference then pull the StringArrays
like so:
Type annotationTypeObj = aJCas.getRequiredType("com.my.Annotation");
//parameter is the canonized name of the Annotation type
Feature keyFeature = annotationTypeObj.getFeatureByBaseName("keyFeatureName");
//the actual name of the feature storing the key StringArray reference
Feature valuesFeature =
annotationTypeObj.getFeatureByBaseName("valuesFeatureName"); //the name of the
values feature
//Get a list of the annotation objects in the CAS then iterate through the
list, for each annotation 'a' do the following to retrieve the keys and values
StringArray keys = (StringArray) vector.getFeatureValue(keysFeature);
StringArray values = (StringArray) vector.getFeatureValue(valuesFeature);
If necessary you can retrieve a String[] from the StringArray FeatureStructure
by calling the .toArray() method such as:
String[] keysArray = keys.toArray();
Let me know if you have any questions.
Thanks,
Thomas Ginter
801-448-7676
thomas.gin...@utah.edu<mailto:thomas.gin...@utah.edu>
On Oct 16, 2013, at 9:55 AM, Dr. Armin Wegner
<arminweg...@googlemail.com<mailto:arminweg...@googlemail.com>> wrote:
Hi,
I'd like to have a type feature that is a list of key-value pairs. The
number of pairs is unknown. What's best for this? Is it even possible?
Thanks,
Armin
