Writes a Graph object to a Json file.
Creates a network graph from loaded Archive Records with optional pageRank calculations.
an RDD of archive records
whether to calculate PageRank (an O(n^2) calculation, so not recommended for very large graphs)
the percentage of the time the PR algorithm "jumps" to a random location in its random walks
the number of iterations applied to the PR algorithm
a Graph object containing data for vertices and edges as extracted.
Creates a hashcode from a url to use as a unique id.
unique id as long integer.