Note

This is the documentation for the current state of the development branch of rustworkx. The documentation or APIs here can change prior to being released.

rustworkx.pagerank#

pagerank(graph, /, alpha=0.85, weight_fn=None, nstart=None, personalization=None, tol=1e-06, max_iter=100, dangling=None)#

Computes the PageRank of the nodes in a PyDiGraph.

For details on the PageRank, refer to:

L. Page, S. Brin, R. Motwani, and T. Winograd. “The PageRank Citation Ranking: Bringing order to the Web”. Stanford Digital Library Technologies Project, (1998). <http://dbpubs.stanford.edu:8090/pub/showDoc.Fulltext?lang=en&doc=1999-66&format=pdf>

This function uses a power iteration method to compute the PageRank and convergence is not guaranteed. The function will stop when max_iter iterations is reached or when the computed vector between two iterations is smaller than the error tolerance multiplied by the number of nodes. The implementation of this algorithm tries to match NetworkX’s pagerank() implementation.

In the case of multigraphs the weights of any parallel edges will be summed when computing the PageRank.

Parameters:

  • graph (PyDiGraph) – The graph object to run the algorithm on

  • alpha (float) – Damping parameter for PageRank, default=0.85.

  • weight_fn – An optional input callable that will be passed the edge’s payload object and is expected to return a float weight for that edge. If this is not specified default_weight will be used as the weight for every edge in graph

  • nstart (dict) – Optional starting value of PageRank iteration for each node.

  • personalization (dict) – An optional dictionary representing the personalization vector for a subset of nodes. At least one personalization entry must be non-zero. If not specified, a nodes personalization value will be zero. By default, a uniform distribution is used.

  • tol (float) – The error tolerance used when checking for convergence in the power method. If this is not specified default value of 1e-6 is used.

  • max_iter (int) – The maximum number of iterations in the power method. If not specified a default value of 100 is used.

  • dangling (dict) – An optional dictionary for the outedges to be assigned to any “dangling” nodes, i.e., nodes without any outedges. The dict key is the node the outedge points to and the dict value is the weight of that outedge. By default, dangling nodes are given outedges according to the personalization vector (uniform if not specified). This must be selected to result in an irreducible transition matrix. It may be common to have the dangling dict to be the same as the personalization dict.

Returns:

a read-only dict-like object whose keys are the node indices and values are the PageRank score for that node.

Return type:

CentralityMapping