def routing(self):
self.D = {} # dictionary of node -> final Costs
self.G = {} # dictionary of node -> Gateway
self.L = {} # dictionary of gateway -> Load
self.Q = priorityDictionary() # est.dist. of non-final vert.
self.H = {} # dictionary of node -> true Hop Counts
self.P = {} # dictionary of node -> Predecessor
for gateway in range(0, self.numGateways):
self.Q[gateway] = 0
self.G[gateway] = gateway
self.L[self.G[gateway]] = 0
self.H[gateway] = 0
for v in self.Q:
self.D[v] = self.Q[v]
if len(self.D) == self.number_of_nodes():
break
#if v in self.cxns:
neigh_v = self.neighbors(v)
if len(neigh_v) > 0:
#for w in self.cxns[v]:
for w in neigh_v:
#Check that it is connected
if self.cxns[v][w]:
gatewayLoad = self.L[self.G[v]]
cost = self.D[v] + self.cxns[v][
w] # old method to calculate using D table.
cost = cost + self.loadFactor * (gatewayLoad) / (200.)
if w in self.D:
if cost < self.D[w]:
raise ValueError(
"Error Dijkstra: Better path to already-final vertex"
)
elif w not in self.Q or cost < self.Q[w]:
self.Q[w] = cost # assign new cost to Q dictionary
self.P[w] = v # assign predecessor for Parent
if self.G.get(w, -1) != -1:
self.L[self.G[w]] = self.L[self.G[w]] - 1
self.G[w] = self.G[
v] # assign same Gateway as Parent
self.L[self.G[v]] = self.L[
self.G[v]] + 1 # increment Gateway load
self.H[w] = self.H[
v] + 1 # assign true Hop Count as increment from Parent
def routing(self):
self.D = {} # dictionary of node -> final Costs
self.G = {} # dictionary of node -> Gateway
self.L = {} # dictionary of gateway -> Load
self.Q = priorityDictionary() # est.dist. of non-final vert.
self.H = {} # dictionary of node -> true Hop Counts
self.P = {} # dictionary of node -> Predecessor
for gateway in range(0,self.numGateways):
self.Q[gateway] = 0
self.G[gateway] = gateway
self.L[self.G[gateway]] = 0
self.H[gateway] = 0
for v in self.Q:
self.D[v] = self.Q[v]
if len(self.D) == self.number_of_nodes():
break
#if v in self.cxns:
neigh_v = self.neighbors(v)
if len(neigh_v) >0:
#for w in self.cxns[v]:
for w in neigh_v:
#Check that it is connected
if self.cxns[v][w]:
gatewayLoad = self.L[self.G[v]]
cost = self.D[v] + self.cxns[v][w] # old method to calculate using D table.
cost = cost + self.loadFactor * (gatewayLoad) / (200.)
if w in self.D:
if cost < self.D[w]:
raise ValueError("Error Dijkstra: Better path to already-final vertex")
elif w not in self.Q or cost < self.Q[w]:
self.Q[w] = cost # assign new cost to Q dictionary
self.P[w] = v # assign predecessor for Parent
if self.G.get(w, -1) != -1:
self.L[self.G[w]] = self.L[self.G[w]] - 1
self.G[w] = self.G[v] # assign same Gateway as Parent
self.L[self.G[v]] = self.L[self.G[v]] + 1 # increment Gateway load
self.H[w] = self.H[v] + 1 # assign true Hop Count as increment from Parent
def dijkstra_algorithm(graph,start,target=None):
start_time = datetime.datetime.now()
final_dist_dict = {} # a dictionary to maintain final distances
dict_predecessor = {} # a dictionary to maintain predessor of nodes
PD = priorityDictionary() # a priority dictionary using binary heaps
PD[start] = 0 # initialize 0 to the start vertex
for u in PD:
final_dist_dict[u] = PD[u]
if u == target: break
for v in graph[u]:
uvLength = final_dist_dict[u] + graph[u][v]['weight']
if v in final_dist_dict:
if uvLength < final_dist_dict[v]: # raise an error if a shorter path exist for an already finalized node
raise ValueError
elif v not in PD or uvLength < PD[v]:
PD[v] = uvLength
dict_predecessor[v] = u
end_time = datetime.datetime.now()
t = (end_time - start_time)
print "Time taken by dijkstra_algorithm in seconds is", t.total_seconds()
return (final_dist_dict,dict_predecessor)
