1. A method of ranking nodes in a graph, comprising: receiving a graph comprising a plurality of nodes and edges at a node ranker of a computer device; selecting a subset of the nodes of the graph using a node selector; generating a plurality of single random walks, wherein generating each single random walk comprises: generating a random walk for each of the nodes in the subset of the nodes of the graph using a random walk generator, each random walk comprising nodes reachable from a selected node in the subset of the nodes by following edges of the graph starting from the selected node; appending the generated random walks together to create the single random walk using the random walk generator, the single random walk being longer than each random walk for each of the nodes in the subset of the nodes of the graph; and determining a probability that a node from the subset of nodes appears in a single random walk using the generated plurality of single random walks.