def bfsTree(self, root): """ calculates a breadth-first search tree from the edges in the passed HyGraph, starting from the root vertex. "Breadth-first" in the sense that all vertices reachable in step i are added to the tree before any of the newly-reachable vertices' reachable vertices are explored. The returned tree (implied in the parent relationships) consists of simple edges, not the original hyperedges of the HyGraph instance. Input Arguments: root: an integer denoting the root vertex for the tree Input Arguments: parents: a ParVec instance of length equal to the number of vertices in the HyGraph, with each element denoting the vertex number of that vertex's parent in the tree. The root is its own parent. Unreachable vertices have a parent of -1. SEE ALSO: isBfsTree """ parents = pcb.pyDenseParVec(self.nvert(), -1) fringeV = pcb.pySpParVec(self.nvert()) parents[root] = root fringeV[root] = root while fringeV.getnee() > 0: fringeV.setNumToInd() fringeE = self._spm.SpMV_SelMax(fringeV) fringeV = self._spmT.SpMV_SelMax(fringeE) pcb.EWiseMult_inplacefirst(fringeV, parents, True, -1) parents[fringeV] = 0 parents += fringeV return ParVec.toParVec(parents)
def degree(self): """ calculates the degree of each vertex of the passed HyGraph instance. Input Arguments: self: a HyGraph instance Output Argument: ret: a ParVec instance with each element containing the degree of the corresponding vertex. SEE ALSO: sum """ if self.nedge() == 0: return ParVec.zeros(self.nvert()) ret = self._spm.Reduce(pcb.pySpParMat.Column(),pcb.plus(), pcb.ifthenelse(pcb.bind2nd(pcb.not_equal_to(), 0), pcb.set(1), pcb.set(0))) return ParVec.toParVec(ret)
def npin(self): """ calculates the cardinality of each edge of the passed HyGraph instance. Input Arguments: self: a HyGraph instance Output Argument: ret: a ParVec instance with each element containing the cardinality of the corresponding edge. SEE ALSO: rank, antirank """ if self.nedge() == 0: return ParVec.zeros(self.nedge()) ret = self._spm.Reduce(pcb.pySpParMat.Row(),pcb.plus(), pcb.ifthenelse(pcb.bind2nd(pcb.not_equal_to(), 0), pcb.set(1), pcb.set(0))) return ParVec.toParVec(ret)