def prim(graph, start_node):
queue = PriorityQueue()
parent = {}
mst = []
mst_sum = 0
for node in graph.get_nodes():
queue.add_task(task=node, priority=float('Inf'))
parent[node] = None
# put first node in the queue
queue.add_task(task=start_node, priority=0)
while queue.not_empty():
cheapest_node = queue.pop_task()
if parent[cheapest_node] is not None:
temp_weight = float(graph.get_default_weights((cheapest_node, parent[cheapest_node]))[0])
mst.append((temp_weight, (cheapest_node, parent[cheapest_node])))
mst_sum += temp_weight
for adj_node in graph.get_node_neighbours(cheapest_node):
edge_weight = float(graph.get_default_weights((cheapest_node, adj_node))[0])
if queue.contains_task(adj_node) and edge_weight < queue.get_priority(adj_node):
parent[adj_node] = cheapest_node
queue.add_task(task=adj_node, priority=edge_weight)
print "Prim Weight: ", mst_sum
return mst
