Example #1
0
	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)
Example #2
0
	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)
Example #3
0
	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)
Example #4
0
	def __init__(self,*args):
		"""
		creates a new HyGraph instance.  Can be called in one of the 
		following forms:

	HyGraph():  creates a HyGraph instance with no vertices or edges.  Useful
		as input for genGraph500Edges.

	HyGraph(edgeNumV, incidentVertexV, weightV, nvert, [nedge])
		create a HyGraph instance.  Each element of the first (ParVec) 
		argument denotes an edge number;  each corresponding element of
		the second (ParVec) argument denotes the number of a vertex to 
		which the edge is incident.  A single edge number can occur an 
		arbitrary number of times in the first argument; all the vertices 
		denoted for the same edge collectively define the hyperedge.  
		The third argument may be a ParVec instance or a scalar;  if a 
		ParVec, then its corresponding elements denote the weight of the
		edge for its incident vertex;  if a scalar, then it denotes the 
		weight of all edges for all incident vertices.  The nvert argument
		denotes the number of vertices in the resulting HyGraph (not all
		vertices must have incident edges).  The optional nedge argument
		denotes the number of edges in the resulting HyGraph (not all edges
		must be incident vertices).

		Input Arguments:
			edgeNumV:  a ParVec containing integers denoting the 
			    edge number of each edge.
			incidentVertexV:  a ParVec containing integers denoting 
			    incident vertices.
			weightV:  a ParVec containing double-precision floating-
			    point numbers denoting the weight of each edge incident
			    to a vertex, or a double-precision floating-point 
			    scalar denoting the weight of all edges for all
			    incident vertices.
			nvert:  an integer scalar denoting the number of vertices.
			nedge:  an optional integer scalar argument denoting the 
			    number of edges

		Output Argument:  
			ret:  a HyGraph instance

		SEE ALSO:  toParVec
		"""
		if len(args) == 0:
			self._spm = pcb.pySpParMat()
			self._spmT = pcb.pySpParMat()
		elif len(args) == 4:
			[i,j,v,nv] = args
			if len(i) != len(j):
				raise KeyError, 'first two arguments must be same length'
			if type(v) == int or type(v) == long or type(v) == float:
				v = ParVec.broadcast(len(i),v)
			ne = int(i.max()) + 1
			if j.max() > nv-1:
				raise KeyError, 'at least one second index greater than #vertices'
			self._spm = pcb.pySpParMat(ne,nv,i._dpv,j._dpv,v._dpv)
			self._spmT = self._spm.copy()
			self._spmT.Transpose()
		elif len(args) == 5:
			[i,j,v,nv,ne] = args
			if len(i) != len(j):
				raise KeyError, 'first two arguments must be same length'
			if type(v) == int or type(v) == long or type(v) == float:
				v = ParVec.broadcast(len(i),v)
			if i.max() > ne-1:
				raise KeyError, 'at least one first index greater than #edges'
			if j.max() > nv-1:
				raise KeyError, 'at least one second index greater than #vertices'
			self._spm = pcb.pySpParMat(ne,nv,i._dpv,j._dpv,v._dpv)
			self._spmT = self._spm.copy()
			self._spmT.Transpose()
		else:
			raise NotImplementedError, "only 0-, 4- and 5-argument cases supported"