Load Instances via PatientService and store into XML (XRFF)

loadInstancesAsXML

import weka.core.converters.Loader;
import weka.core.converters.Saver;
import weka.core.converters.ArffLoader;
import weka.core.converters.XrffSaver;

IPatientService ps = ... //get IPatientService
Data d = ... //get Data entity
Path pathToArff = locateFile(Data d);
Path pathToXML = ... //get it!
try(InputStream in = Files.newInputStream(pathToArff); OutputStream out = Files.newOutputStream(pathToXML) {
 Loader loader = new ArffLoader();
 loader.setSource(Files.newInputStream(pathToArff));
 Instances dataset = loader.getDataSet();

 Saver saver = new XrffSaver();
 saver.setInstances(dataset);
 
 //This won't work with Weka 3.7.3, fixed in 3.7.5. Needs update
 //saver.setDestination(out);
 
 //As a workaround use
 saver.setDestination(pathToXML.toFile());
 saver.writeBatch();
 
} catch(IOException e) {
 //handle it!
}