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GraphStructures.py
147 lines (139 loc) · 5.76 KB
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GraphStructures.py
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# Import graphviz
import sys, os, copy
sys.path.append('..')
sys.path.append('/usr/lib/graphviz/python/')
sys.path.append('/usr/lib64/graphviz/python/')
import graphviz
from graphviz import Digraph
class GraphError(Exception):
def __init__(self, message):
self.message = message
def __str__(self):
return repr(self.message)
class Node():
def __init__(self, node_id, node_content, meta=""):
self.id = node_id
self.content = node_content
# space for arbitrary meta information
self.meta = meta
class Graph():
def __init__(self):
self.nodes = {}
self.edges = {}
def add_node(self, node):
self.nodes[node.id] = node
self.edges[node.id] = []
def add_edge(self, source_node_id, destination_node_id):
if(source_node_id not in self.nodes or destination_node_id not in self.nodes):
raise GraphError("nodes for this edge not present")
else:
self.edges[source_node_id].append(destination_node_id)
def render(self, filename, comment, render="content"):
dot = Digraph(comment=comment,edge_attr={'len': '6', 'weight':'0.00001'})
dot.engine = 'dot'
# add nodes to dot graph
for node_key in self.nodes.keys():
node_content = "nil"
# either use id or content to mark graph nodes
if render == "id":
node_content = str(self.nodes[node_key].id)
elif render == "content":
if len(self.nodes[node_key].content) > 0:
node_content = ', '.join(str(x) for x in self.nodes[node_key].content)
else:
node_content = str(self.nodes[node_key].id) + ":"
if len(self.nodes[node_key].content) > 0:
node_content += ', '.join(str(x) for x in self.nodes[node_key].content) + ":"
else:
node_content += "nil:"
if len(self.nodes[node_key].meta) > 0:
node_content += self.nodes[node_key].meta
else:
node_content += "nil"
dot.node(str(self.nodes[node_key].id), node_content)
#add edges to dot graph
for edge_key in self.edges.keys():
for dest_node in self.edges[edge_key]:
dot.edge(str(edge_key), str(dest_node))
if not os.path.exists("graph"):
os.makedirs("graph")
dot.render("graph/" + filename + ".gv")
class GraphTool():
# reverse direction of edges ...
def reverse_digraph(self, graph):
reverse_graph = copy.deepcopy(graph)
for i in range(0, len(graph.nodes)):
node = graph.nodes[i]
for dest_node_id in graph.edges[node.id]:
reverse_graph.add_edge(dest_node_id, node.id)
reverse_graph.edges[node.id].remove(dest_node_id)
return reverse_graph
class TraversalTool():
# returns node traversal, breadth first
def bf_trav(self, graph):
node_stack = []
nodes_unvisited = [x for x in range(0,len(graph.nodes) + 1)]
traversal_list = []
#remove start node and push to stack
nodes_unvisited.remove(0)
node_stack.append(0)
traversal_list.append(0)
while len(node_stack) != 0:
current_node = node_stack.pop()
for child in graph.edges[current_node]:
if child in nodes_unvisited:
nodes_unvisited.remove(child)
node_stack.append(child)
traversal_list.append(child)
return traversal_list
# return (dfs) topological sorting of the nodes
def topo_trav(self, graph):
dfs_tree = DfsTree(graph)
sorted_tuples = sorted(list(zip(dfs_tree.all_node_ids, dfs_tree.finish_time)), key=lambda time:time[1])
sorted_node_ids = [tpl[0] for tpl in sorted_tuples]
return list(reversed(sorted_node_ids))
class DfsTree():
def __init__(self, graph):
self.graph = graph
self.node_stack = []
self.node_color = []
self.discovery_time =[]
self.finish_time = []
self.predecessor = []
self.time = 0
self.all_node_ids = []
for i in range(0, len(graph.nodes)):
self.node_color.append('white')
self.discovery_time.append(0)
self.finish_time.append(0)
self.predecessor.append(None)
self.all_node_ids.append(graph.nodes[i].id)
self.dfs()
def dfs(self):
for i in range(0, len(self.graph.nodes)):
if self.node_color[self.graph.nodes[i].id] == 'white':
self.dfs_visit(self.graph.nodes[i])
def dfs_visit(self, node):
# actual algorithm ..
self.node_color[node.id] = 'gray'
self.time += 1
self.discovery_time[node.id] = self.time
# the child nodes are directly stored as integers, so we can use them directly here
for succ in self.graph.edges[node.id]:
if self.node_color[succ] == 'white':
self.predecessor[succ] = node.id
self.dfs_visit(self.graph.nodes[succ])
self.node_color[node.id] = 'black'
self.time += 1
self.finish_time[node.id] = self.time
def print_results(self):
# generate result lists
finish = sorted(list(zip(self.all_node_ids, self.finish_time)), key=lambda time:time[1])
disc = list(zip(self.all_node_ids, self.discovery_time))
col = list(zip(self.all_node_ids, self.node_color))
pre = list(zip(self.all_node_ids, self.predecessor))
# print them
print("SORTED FINISH TIMES:" + str(finish))
print("DISCOVERY TIMES:" + str(disc))
print("COLORS:" + str(col))
print("PREDECESSORS:" + str(pre))