Split

import weka.core.Instance;
import weka.core.Instances;
import weka.core.converters.ArffSaver;
import weka.core.converters.ConverterUtils;
import weka.core.converters.Saver;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class Split {

    private File testFile;
    private File trainFile;

    private Split(String fileName, long seed, double split, int iterations) throws Exception {

        ConverterUtils.DataSource dataSource = new ConverterUtils.DataSource("split input/" + fileName);
        Instances instances = dataSource.getDataSet();

        List<Instance> instanceList = new ArrayList<>(instances);

        int length = Math.round((float) split * instances.size());

        Random random = new Random(seed);
        for (int i = 1; i < iterations + 1; i++) {
            prepareFiles(fileName, i);

            Collections.shuffle(instanceList, random);

            ArffSaver trainSaver = new ArffSaver();
            trainSaver.setStructure(instances);
            trainSaver.setRetrieval(Saver.INCREMENTAL);
            trainSaver.setFile(trainFile);
            for (int index = 0; index < length; index++) {
                trainSaver.writeIncremental(instanceList.get(index));
            }
            trainSaver.getWriter().flush();
            trainSaver.getWriter().close();

            ArffSaver testSaver = new ArffSaver();
            testSaver.setStructure(instances);
            testSaver.setRetrieval(Saver.INCREMENTAL);
            testSaver.setFile(testFile);
            for (int _index = 0; _index < instances.size() - length; _index++) {
                int index = length + _index;
                testSaver.writeIncremental(instanceList.get(index));
            }
            testSaver.getWriter().flush();
            testSaver.getWriter().close();
        }
    }

    public static void main(String[] args) throws Exception {
        new Split("Glass.arff", 5, 0.66, 5);
    }

    private void prepareFiles(String fileName, int iteration) throws IOException {
        String outputName = fileName.substring(0, fileName.lastIndexOf("."));

        File dir = new File(String.format("split/%s", outputName));

        testFile = new File(String.format("%s/%s_test_%d.arff", dir.getPath(), outputName, iteration));
        trainFile = new File(String.format("%s/%s_train_%d.arff", dir.getPath(), outputName, iteration));


        if (dir.mkdirs()) {
            testFile.createNewFile();
            trainFile.createNewFile();
        }
    }
}