code: public static Map<Object, int[]> countAnnotationsPerCategory(
  			final ICodingAnnotationStudy study) {
  		Map<Object, int[]> result = new HashMap<Object, int[]>();
  		for (ICodingAnnotationItem item : study.getItems()) {
              for (IAnnotationUnit unit : item.getUnits()) {
  				Object category = unit.getCategory();
  				if (category == null) {
                      continue;
                  }
  
  				int[] counts = result.get(category);
  				if (counts == null) {
                      counts = new int[study.getRaterCount()];
                  }
  				counts[unit.getRaterIdx()]++;
  				result.put(category, counts);
  			}
          }
  		return result;
  	}
docs: Category x Rater -> #