print("Starting at {}, ending at {}".format(start, stop))
if len(graph.neighbours_of(G, start)) == 0:
raise Exception("Bad luck, {} has no neighbours".format(start))
num_steps = 0
display.write_dot_desc(G, dot_file_name, attr)
cur = start
while cur != stop and num_steps < max_num_steps:
display.pause(0)
num_steps += 1
print("Step {} at {}".format(num_steps, cur))
# find a random neighbour of cur
prev = cur
neighbours = graph.neighbours_of(G, cur)
cur = random.choice(list(neighbours))
# do some coloring before next graph render
attr["vertex_color"][prev]="white"
attr["vertex_color"][start]="green"
attr["vertex_color"][cur]="orange"
attr["vertex_color"][stop]="red"
attr["edge_color"][graph.mk_edge(prev, cur)]="orange"
display.write_dot_desc(G, dot_file_name, attr)
print("Finished, after {} steps we are at {}".format(num_steps, cur))
if cur != stop:
print("We failed to reach the stop vertex {}".format(stop))
for x in graph.neighbours_of(G, v):
if x not in visited:
w = x
break
if w is not None:
# mark w as visited
visited.add(w)
print("visiting {} at step {}".format(w, edge_seq_num))
level[w] = level[v] + 1
# color and label the visited vertex
attr["vertex_color"][w]="orange"
attr["vertex_label"][w]= str(w) + ":" + str(level[w])
# color the new edge v, w
attr["edge_label"][graph.mk_edge(v, w)]=edge_seq_num
edge_seq_num += 1
attr["edge_color"][graph.mk_edge(v, w)]="orange"
# update the rendering
display.write_dot_desc(G, dot_file_name, attr)
display.pause(0)
# push w on visit stack
visit_stack.append(w)
else:
# no unvisited neighbours, back track
visit_stack.pop()
