def isCycle(graph):
""" This function takes a networkx graph object as input and returns True if the graph is a cycle
Note: A graph is a cycle iff degree of every node is two and the graph is connected.
"""
if graph:
degree_hist = nx.degree_histogram(graph) # get frequency of degree of all nodes
if degree_hist[2] == len(graph.nodes()) and nx.is_connected(graph): # if all nodes have degree = 2 => cycle
Debuglogger.debug("Is a cycle")
return True
Debuglogger.debug("Is not a cycle")
return False
def getCycleBasis(graph):
""" Input: networkx simple graph
Returns list of graph objects that form cycle basis of the input graph
"""
Debuglogger.info("In getCycleBasis")
cycle_basis_list = [] # list of list of edges of each cycle basis
for cycle in nx.cycle_basis(graph):
Debuglogger.debug("cycle basis ->"+str(cycle))
cycle_graph = nx.Graph()
cycle_graph.add_cycle(cycle)
cycle_basis_list.append(cycle_graph.edges())
return cycle_basis_list
def getAllRings(graph, isMultigraph):
""" Parameters: graph -> networkx graph or multigraph object,
isMultigraph -> True if graph is multigraph else false
Returns list of list of edges forming cycles in the graph.
"""
if isMultigraph:
multigraph, graph = graph, nx.Graph(graph)
all_cycle_edge_list = []
Debuglogger.info("Getting cycle basis")
cycle_basis_list = getCycleBasis(graph) # get cycle basis of given graph
Userlogger.info('\nGetting all the rings from physical topology')
for i in range(1,len(cycle_basis_list)+1): # form combinations of cycle basis
Debuglogger.debug("Getting combinations of basis cycle picking "+str(i)+" items")
for combination in combinations(cycle_basis_list,i):
if combination:
Debuglogger.debug("combination exists")
edge_set = {}
for basis in combination: # find symmetric difference of
edge_set = set(basis).symmetric_difference(edge_set)# members of each combination
ring = nx.Graph()
ring.add_edges_from(list(edge_set))
if isCycle(ring): #if the member is a connected cycle
Debuglogger.debug("Is a connected cycle")
all_cycle_edge_list.append(list(edge_set)) # add to list of all cycles
Debuglogger.info("Ring "+str(len(all_cycle_edge_list))+" "+str(all_cycle_edge_list[-1]))
Userlogger.info("Ring "+str(len(all_cycle_edge_list))+" "+str(all_cycle_edge_list[-1]))
if isMultigraph:
return getRingsMultigraph(multigraph, all_cycle_edge_list)
return all_cycle_edge_list
def formatCycleEdgeList(graph, isMultigraph, all_cycle_edge_list_tuple, SwitchList):
""" Input -> graph object, bool whether multigraph or not, list of list of edges forming a cycle, dictionary port-port mappin gfor each node
Returns list of list of edges forming cycle with attribute information
"""
Debuglogger.info("In formatCycleEdgeList - isMultigraph: "+str(isMultigraph))
all_cycle_edge_list_str = []
for ring in all_cycle_edge_list_tuple:
cycle_str = []
for edge in ring:
node1 = edge[0]
node2 = edge[1]
if not isMultigraph:
edge_dict = graph[node1][node2]
else:
edge_dict = graph[node1][node2][edge[-1]]
if edge_dict['wt'] in SwitchList[node1]:
edge = (node1, node2, edge_dict['wt'], edge_dict['link_type'])
else: edge = (node2, node1, edge_dict['wt'], edge_dict['link_type'])
edge = " ".join(edge)
#Debuglogger.debug(edge)
cycle_str.append(edge)
Debuglogger.debug(cycle_str)
all_cycle_edge_list_str.append(cycle_str)
return all_cycle_edge_list_str
def getRingsMultigraph(multigraph, all_cycle_edge_list):
""" Input -> multigraph object, list of cycles or rings got from simple graph
Returns list of list of edges of a ring. Edge is represented as (node1.node2,edge_id)
"""
Debuglogger.info("In getRingsMultigraph")
all_cycle_edge_list_multi = []
for ring in all_cycle_edge_list:
Debuglogger.debug("Ring:"+str(ring))
cycle = []
multi_edge_list = []
edge_index = []
for edge in ring:
Debuglogger.debug("Edge:"+str(edge))
node1 = edge[0]
node2 = edge[1]
if len(multigraph[node1][node2])>1:
Debuglogger.info("this ia a multi edge")
single_multi_edge = []
for edge_id in multigraph[node1][node2].keys():
single_multi_edge.append((node1, node2, edge_id))
edge_new = single_multi_edge[0]
multi_edge_list.append(single_multi_edge)
edge_index.append(ring.index(edge))
else:
edge_new = edge + (0,)
cycle.append(edge_new)
all_cycle_edge_list_multi.append(cycle)
Debuglogger.debug("multi_edge_list:"+str(multi_edge_list))
if multi_edge_list:
for combination in product(*multi_edge_list):
for i in range(len(combination)):
idx = edge_index[i]
temp = cycle[:idx]+[combination[i]]
if i<len(cycle):
temp+=cycle[idx+1:]
cycle = temp
#print cycle
if temp not in all_cycle_edge_list_multi:
all_cycle_edge_list_multi.append(temp)
Userlogger.info("Ring "+str(len(all_cycle_edge_list_multi))+" "+str(temp))
Debuglogger.info("Ring "+str(len(all_cycle_edge_list_multi))+" "+str(temp))
return all_cycle_edge_list_multi
