Frank Kane's Taming Big Data with Apache Spark and Python

Second pass through the graph

We then pass through it all again. We now have to then expand the r and w nodes. Let's start with w. Color it black, this means that we've processed it, color its connections gray, this means that they need to be explored next, and increment the distance one more time:

Now we know that the x and t nodes are two degrees of separation from the Hulk. We still have to handle the r circle, so color it black, increment the distance to 2 and color this new node that we just discovered, the v node, gray, meaning that we need to explore the v node further as well:

So this is the end of our second pass through the graph. ...