code: private double computeDepth() throws WikiApiException {
          Category root = wiki.getMetaData().getMainCategory();
          if (root == null) {
              logger.error("There is no root node for this wiki. Check the parameter that provides the name of the root node.");
              return 0.0;
          }
          // test whether the root category is in this graph
          if (!graph.containsVertex(root.getPageId())) {
              logger.error("The root node is not part of this graph. Cannot compute depth of this graph. Setting depth to 0.0");
              return 0.0;
          }
          double maxPathLength = 0.0;
          double[] returnValues = computeShortestPathLenghts(root.getPageId(), 0.0, maxPathLength, new HashSet<Integer>());
          maxPathLength         = returnValues[1];
          return maxPathLength;
      }
docs: Computes the depth of the category graph, i.e. the maximum path length starting with the root node.
  @return The depth of the hierarchy.
  @throws WikiApiException Thrown if errors occurred.