/**
   * Initialize this separate model using a complete list.
   *
   * @param documents
   * @param testStartIndex
   */
  public void divideDocuments(InstanceList documents, int testStartIndex) {
    Alphabet dataAlpha = documents.getDataAlphabet();
    Alphabet targetAlpha = documents.getTargetAlphabet();

    this.training = new InstanceList(dataAlpha, targetAlpha);
    this.test = new InstanceList(dataAlpha, targetAlpha);
    int di = 0;
    for (di = 0; di < testStartIndex; di++) {
      training.add(documents.get(di));
    }
    for (di = testStartIndex; di < documents.size(); di++) {
      test.add(documents.get(di));
    }
  }