def eppstein_ksp(self,
G: DiGraph,
source: Any,
target: Any,
K: int = 1,
weight="weight") -> List[NamedTuple]:
self.target = target
T = ConstructShortestPathTree(
G.reverse(), target, weight=weight) # reversed shortest path tree
self.setDelta(G, T, weight=weight)
nodeHeaps = dict()
outrootHeaps = dict()
for node in G.nodes():
self.computeH_out(node, G, nodeHeaps, weight=weight)
rootArrayHeap = EppsteinArrayHeap()
self.computeH_T_recursive(target, rootArrayHeap, nodeHeaps,
outrootHeaps, T)
hg = EppsteinHeap(Edge(source, source, weight=0))
ksp = []
pathPQ = []
heappush(pathPQ, EppsteinPath(hg, -1, T.nodes()[source]["distance"]))
k = 0
while k < K and pathPQ:
# Checked
kpathImplicit = heappop(pathPQ)
kpath = kpathImplicit.explicitPath(G,
T,
ksp,
target,
weight=weight)
ksp.append(kpath)
self.addHeapEdgeChildrenToQueue(kpathImplicit, ksp,
pathPQ) # heap edge
self.addCrossEdgeChildToQueue(outrootHeaps, kpathImplicit, k, ksp,
pathPQ) # cross edge
k += 1
return ksp
