def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
cur = self
for i in range(0, self.n): # Iterate through all vertex ID
if (i == srcID): # If ID is srcID
pq.set(i, 0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
minKey, minDist = pq.extractMin()
d[minKey] = minDist #set orignal source distance to 0
pi[minKey] = minKey #set sources to orginal source
while (pq.isEmpty() == False): # COMPLETE the Dijkstra code here
lst = self.adjList[
minKey] #grap array of lists of format (vertices,weight) for node minKey
for n in lst: #loop through said list
##grap the next node attached to this node somehow
dist = n[1] + minDist #grab distance from list
node = n[0] #grab node from list
if (pq.hasKey(node)
): #check if that nodes min dist has been found
if (
pq.get(node) > dist
): #check if path to the node from minKey is less then current path
pq.set(node,
dist) #set the nodes distance in the queue
d[node] = dist #set the nodes distance in the return array
pi[node] = minKey #sets the nodes parents
minKey, minDist = pq.extractMin(
) #extract next node dont need to extract last node as all the paths will be filled would probably work better in a do while loop
return (d, pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
cur=self
for i in range(0,self.n): # Iterate through all vertex ID
if ( i == srcID): # If ID is srcID
pq.set(i,0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
minKey, minDist=pq.extractMin()
d[minKey]=minDist #set orignal source distance to 0
pi[minKey]=minKey #set sources to orginal source
while(pq.isEmpty()==False):# COMPLETE the Dijkstra code here
lst=self.adjList[minKey]#grap array of lists of format (vertices,weight) for node minKey
for n in lst:#loop through said list
##grap the next node attached to this node somehow
dist=n[1]+minDist#grab distance from list
node=n[0] #grab node from list
if(pq.hasKey(node)):#check if that nodes min dist has been found
if(pq.get(node)>dist):#check if path to the node from minKey is less then current path
pq.set(node,dist)#set the nodes distance in the queue
d[node]=dist#set the nodes distance in the return array
pi[node]=minKey#sets the nodes parents
minKey, minDist=pq.extractMin()#extract next node dont need to extract last node as all the paths will be filled would probably work better in a do while loop
return (d,pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n) # ensure that srcID is between 0 and size of graph.
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0,self.n): # Iterate through all vertex ID
if i == srcID: # If ID is srcID
pq.set(i, 0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
while not pq.isEmpty(): # loop until priority queue is empty.
(node, dist) = pq.extractMin() # extract smallest dist node.
d[node] = dist # update dictionary with shortest distance.
for (vertex, weight) in self.adjList[node]: # check the adjacency list of popped node.
newDist = dist + weight # calculate new distance.
if pq.hasKey(vertex): # if we haven't already popped the node in the adjacency list yet.
if newDist < pq.get(vertex): # check distance vs new calculated dist.
pq.set(vertex, newDist) # update priority queue.
pi[vertex] = node # update parent list.
return (d, pi)
def dijkstra(graphObj, startVertex):
pq = PriorityQueue()
for vertex in graphObj.getVertices():
if vertex == startVertex:
pq.insert([0, vertex])
graphObj.verticesList[startVertex].distance = 0
else:
pq.insert([INFINITY, vertex])
while(len(pq.pqueue)):
currentVertex = pq.extractMin()
if len(pq.pqueue) == 1:
break
# print(pq.pqueue, pq.lookup)
for adjNode in graphObj.verticesList[currentVertex[1]].getConnections():
newDistance = graphObj.verticesList[currentVertex[1]].distance + graphObj.verticesList[currentVertex[1]].adjList[adjNode]
if newDistance < graphObj.verticesList[adjNode].distance:
graphObj.verticesList[adjNode].distance = newDistance
graphObj.verticesList[adjNode].predecessor = currentVertex[1]
index = pq.lookup[adjNode]
pq.decreaseKey(index, newDistance)
return graphObj
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0,self.n): # Iterate through all vertex ID
if ( i == srcID): # If ID is srcID
pq.set(i,0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
d[srcID] = 0 # first node to dist map since while won't catch it.
while not pq.isEmpty():
min = pq.extractMin()
# Look at neighbors
for neighbor in self.adjList[min[0]]: # where neighbor has not yet been removed from pq?
alt = min[1] + neighbor[1]
if pq.hasKey(neighbor[0]) and alt < pq.get(neighbor[0]): # previously stored needs to be replayed
# Update distances and parents everywhere
pq.set(neighbor[0], alt)
d[neighbor[0]] = alt
pi[neighbor[0]] = min[0]
return (d,pi)
def prims(graphObj, start):
pq = PriorityQueue()
for vertex in graphObj.verticesList:
if vertex == start:
g.verticesList[vertex].distance = 0
pq.insert([0, vertex])
continue
g.verticesList[vertex].distance = INFINITY
pq.insert([INFINITY, vertex])
while(len(pq.pqueue)):
currentVertex = pq.extractMin()
if len(pq.pqueue) == 1:
return
for adjNode in graphObj.verticesList[currentVertex[1]].getConnections():
if adjNode in pq.lookup(adjNode):
newDistance = graphObj.verticesList[currentVertex[1]].getCost(adjNode)
if newDistance < graphObj.verticesList[adjNode].distance:
graphObj.verticesList[adjNode].distance = newDistance
graphObj.verticesList[adjNode].predecessor = currentVertex[1]
return graphObj
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0, self.n): # Iterate through all vertex ID
if (i == srcID): # If ID is srcID
pq.set(i, 0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
# COMPLETE the Dijkstra code here
if srcID == None or self.adjList[
srcID] == None: #make sure srcId is not None
return
Dist = 0.0
for i in range(0, self.n): #iniatialize dictionaries to default values
d[i] = pq.Inf
pi[i] = i
d[srcID] = 0.0 #set source to zero
while (not pq.isEmpty()): #check if the queue is empty
j = pq.extractMin(
) #tuple of min distance and vertex. j = (vertex,minDist)
for i in self.adjList[j[0]]:
if pq.hasKey(
i[0]
): #assertion of pq.get(i) is that i must be in the priority queue
if i[1] + j[1] < pq.get(
i[0]
): #if distance of prior two nodes is less than current distance
Dist = j[1] + i[1]
pq.set(i[0], Dist) #update distance at vertex to Dist
pi[i[0]] = j[0] #map vertex to its parent
d[i[0]] = Dist #map vertex to its new distance
return (d, pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0, self.n): # Iterate through all vertex ID
if (i == srcID): # If ID is srcID
pq.set(i, 0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
parent = None
while not pq.isEmpty():
minNode = pq.extractMin()
if parent is None:
d[minNode[0]] = minNode[1]
pi[minNode[0]] = minNode[0]
elif minNode[1] != pq.Inf:
d[minNode[0]] = float(round(decimal.Decimal(minNode[1]), 2))
else:
d[minNode[0]] = pq.Inf
lst = self.adjList[minNode[0]]
for i in range(len(lst)):
if pq.hasKey(lst[i][0]) and pq.get(
lst[i][0]) > lst[i][1] + d[minNode[0]]:
pi[lst[i][0]] = minNode[0]
pq.set(lst[i][0], lst[i][1] + d[minNode[0]])
parent = minNode[0]
return (d, pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0,self.n): # Iterate through all vertex ID
if ( i == srcID): # If ID is srcID
pq.set(i,0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
parent = None
while not pq.isEmpty():
minNode = pq.extractMin()
if parent is None:
d[minNode[0]] = minNode[1]
pi[minNode[0]] = minNode[0]
elif minNode[1] != pq.Inf:
d[minNode[0]] = float(round(decimal.Decimal(minNode[1]), 2))
else:
d[minNode[0]] = pq.Inf
lst = self.adjList[minNode[0]]
for i in range(len(lst)):
if pq.hasKey(lst[i][0]) and pq.get(lst[i][0]) > lst[i][1] + d[minNode[0]]:
pi[lst[i][0]] = minNode[0]
pq.set(lst[i][0], lst[i][1] + d[minNode[0]])
parent = minNode[0]
return (d,pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0,self.n): # Iterate through all vertex ID
if ( i == srcID): # If ID is srcID
pq.set(i,0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
# COMPLETE the Dijkstra code here
# self.n : number of vertices in the graph
# self.adjList: Adjacency list stored as a list of lists.
# self.adjList[i] stores all adjacent nodes to vertex ID i along with edge weights.
# Eg., if vertex 2 has three edges (2,3) with weight 4.5, (2,4) with weight 3.2, and (2,5) with 2.1
# self.adjList[2] is the list [ (3,4.5), (4,3.2), (5,2.12) ]
# your goal is to implement the singleSourceShortestPath function.
while not pq.isEmpty():
(n, dist) = pq.extractMin()
d[n] = dist
neighbors = self.adjList[n]
for i in range (0, len(neighbors)):
(v, e) = neighbors[i]
if pq.hasKey(v):
oldDist = pq.get(v) #is it more efficient if these constants are declared outside the loop?
newDist = dist + e
if newDist < oldDist:
pq.set(v, newDist)
pi[v] = n
return (d,pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n
) # ensure that srcID is between 0 and size of graph.
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0, self.n): # Iterate through all vertex ID
if i == srcID: # If ID is srcID
pq.set(i, 0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
while not pq.isEmpty(): # loop until priority queue is empty.
(node, dist) = pq.extractMin() # extract smallest dist node.
d[node] = dist # update dictionary with shortest distance.
for (vertex, weight) in self.adjList[
node]: # check the adjacency list of popped node.
newDist = dist + weight # calculate new distance.
if pq.hasKey(
vertex
): # if we haven't already popped the node in the adjacency list yet.
if newDist < pq.get(
vertex): # check distance vs new calculated dist.
pq.set(vertex, newDist) # update priority queue.
pi[vertex] = node # update parent list.
return (d, pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0, self.n): # Iterate through all vertex ID
if (i == srcID): # If ID is srcID
pq.set(i, 0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
d[srcID] = 0 # first node to dist map since while won't catch it.
while not pq.isEmpty():
min = pq.extractMin()
# Look at neighbors
for neighbor in self.adjList[min[
0]]: # where neighbor has not yet been removed from pq?
alt = min[1] + neighbor[1]
if pq.hasKey(neighbor[0]) and alt < pq.get(
neighbor[0]): # previously stored needs to be replayed
# Update distances and parents everywhere
pq.set(neighbor[0], alt)
d[neighbor[0]] = alt
pi[neighbor[0]] = min[0]
return (d, pi)
def singleSourceShortestPath(self, srcID):
assert (srcID >= 0 and srcID < self.n)
# Implement Dijkstra's algorithm
# Input:
# self --> a reference to a MyGraph instance
# srcID: the id of the source vertex.
# Expected Output: (d,pi)
# d --> Map each vertex id v to the distance from srcID
# pi --> Map each reachable vertex id v (except for srcID) to a parent.
# Initialize the priority queue
pq = PriorityQueue(self.n) #create the priority queue
for i in range(0,self.n): # Iterate through all vertex ID
if ( i == srcID): # If ID is srcID
pq.set(i,0.0) # Distance of srcID should be zero
else: # ID is not srcID
pq.set(i, pq.Inf) # Distance should be infinity
d = {} # Initialize the map with distances to nodes
pi = {} # Initialize the map with parents of vertices
#Code Starts HERE
d[srcID] = 0 #Set distances from source equal to 0
pi[srcID] = None #Set parents to None
while not pq.isEmpty(): #While the priority queue is not empty
(currentVertex,currentDistance) = pq.extractMin() #Extract the Min
for (nextVertex, weight) in self.adjList[currentVertex]:
newDist = weight + currentDistance
if pq.hasKey(nextVertex): #Check if nextVertex exists in priority queue
if newDist < pq.get(nextVertex): #If the new distance is less
d[nextVertex] = newDist #Set new distnace
pi[nextVertex] = currentVertex #Set the parents
pq.set(nextVertex,newDist) #Set the new distance for the vertex
return (d,pi)