def depth_first_search(self): """ Depht-first search. @rtype: tuple @return: tupple containing a dictionary and two lists: 1. Generated spanning tree 2. Graph's preordering 3. Graph's postordering """ return searching.depth_first_search(self)
def depth_first_search(self): """ Depht-first search. @rtype: tuple @return: A tupple containing tree lists: 1. Generated spanning tree 2. Graph's preordering 3. Graph's postordering """ return searching.depth_first_search(self)
def main():
st = time.perf_counter() #Start a time counter.
if len(sys.argv) == 4: #If the length of the keyword arguments is four...
method = sys.argv[
1] #The second argument is the method/algorithm used to find a solution.
input_file = sys.argv[
2] #The third argument is a .txt file containing the initial and final state of the problem.
output_file = sys.argv[
3] #The fourth argument is a .txt file containing the solution of the problem.
initial_state, goal_state = read_input_file(
filename=input_file
) #Read the input file and return two state objects.
if method == 'breadth': #Check which method is selected and solve the problem accordingly.
solution = breadth_first_search(current_state=initial_state,
goal_state=goal_state,
timeout=300)
elif method == 'depth':
solution = depth_first_search(current_state=initial_state,
goal_state=goal_state,
timeout=300)
elif method == 'best':
solution = heuristic_search(current_state=initial_state,
goal_state=goal_state,
method='best',
timeout=300)
elif method == 'astar':
solution = heuristic_search(current_state=initial_state,
goal_state=goal_state,
method='astar',
timeout=300)
else: #If the method argument is none of the above, print a usage message.
solution = None
print(
'Usage: python bw.py <method> <input filename> <output filename>'
)
if solution == goal_state: #If the solution is equal to the goal state...
number_of_moves = write_output_file(
solution=solution, filename=output_file
) #Write the solution file and return the number of moves.
print('Solution found!')
print('Number of blocks:', len(initial_state.layout.keys()))
print('Method:', method)
print('Number of moves:', number_of_moves)
print('Execution time:', str(round(time.perf_counter() - st, 4)))
else: #Else, if the length of the keyword arguments is not equal to four, print a usage message.
print(
'Usage: python bw.py <method> <input filename> <output filename>')
def depth_first_search(self, root=None): """ Depht-first search. @type root: node @param root: Optional root node (will explore only root's connected component) @rtype: tuple @return: tupple containing a dictionary and two lists: 1. Generated spanning tree 2. Graph's preordering 3. Graph's postordering """ return searching.depth_first_search(self, root)
def find_path(self):
filt = find("t")
st, _, _ = depth_first_search(self.graph, "s", filter=filt)
if "t" not in st:
return None
else:
path = []
sink = "t"
# build up path from spanning tree returned from dfs
while sink != "s":
src = st[sink]
new_edge = (src, sink, self.graph.edge_weight((src, sink)))
path.insert(0, new_edge)
sink = src
return path
def find_path(self):
filt = find("t")
st, _, _ = depth_first_search(self.graph, "s", filter=filt)
if "t" not in st:
return None
else:
path = []
sink = "t"
# build up path from spanning tree returned from dfs
while sink != "s":
src = st[sink]
new_edge = (src, sink, self.graph.edge_weight((src, sink)))
path.insert(0, new_edge)
sink = src
return path
def find_path(graph, source):
filt = find("t")
st, po, _ = depth_first_search(graph, source, filter=filt)
# no path from s -> source -> t exists
if "t" not in st or not graph.has_edge(("s", source)):
return None
else: # construct path from st (spanning tree)
path = []
sink = "t"
while sink != source:
src = st[sink]
new_edge = (src, sink, graph.edge_weight((src, sink)))
path.insert(0, new_edge)
sink = src
source_edge = ("s", source, graph.edge_weight(("s", source)))
path.insert(0, source_edge)
return path
def find_path(graph, source):
filt = find("t")
st, po, _ = depth_first_search(graph, source, filter=filt)
# no path from s -> source -> t exists
if "t" not in st or not graph.has_edge(("s", source)):
return None
else: # construct path from st (spanning tree)
path = []
sink = "t"
while sink != source:
src = st[sink]
new_edge = (src, sink, graph.edge_weight((src, sink)))
path.insert(0, new_edge)
sink = src
source_edge = ("s", source, graph.edge_weight(("s", source)))
path.insert(0, source_edge)
return path
def run(in_graph_file):
# converts a graph in an acceptable form into a representation
# that is usable in MapReduce
mr_file_name = "mr_max_flow.txt"
original_graph = file_to_graph(in_graph_file)
mr_graph = mr_graph_convert(original_graph)
dict_to_graph_file(mr_graph, mr_file_name)
augmented_edges = {}
# counters to keep track of convergence of MapReduce jobs
converge_count = 5
previous_count = -1
while converge_count != 0:
infile = open(mr_file_name, "r")
# uncomment to run on emr
# mr_job = max_flow.MRFlow(args=['-r', 'emr'])
mr_job = max_flow.MRFlow()
mr_job.stdin = infile
with mr_job.make_runner() as runner:
# perform iteration of MapReduce
runner.run()
# process map reduce output
out_buffer = []
for line in runner.stream_output():
# print str(counter) + ": " + line
key, value = extract_key_value(line)
if key == "A_p":
A_p = value
merge_edge_flow(augmented_edges, A_p)
else:
out_buffer.append(line)
# write map reduce output to file for next iteration
outfile = open(mr_file_name, "w")
for line in out_buffer:
key, value = extract_key_value(line)
value.append(A_p)
# value.append(1)
new_line = json.dumps(key) + "\t" + json.dumps(value) + "\n"
outfile.write(new_line)
# check for convergence
move_counts = runner.counters()[0]["move"]
if move_counts["source"] == previous_count:
converge_count -= 1
else:
converge_count = 5
previous_count = move_counts["source"]
infile.close()
outfile.close()
# augment graph based on max flow
# original_graph = dict_graph_to_python_graph(original_graph_dict)
augmented_graph = augment_graph(original_graph, augmented_edges)
# find cut
spanning_tree, preordering, postordering = depth_first_search(
augmented_graph, "s")
min_cut = find_max_flow(original_graph, preordering)
return min_cut, preordering
def run(in_graph_file):
# converts a graph in an acceptable form into a representation
# that is usable in MapReduce
mr_file_name = "mr_max_flow.txt"
original_graph = file_to_graph(in_graph_file)
mr_graph = mr_graph_convert(original_graph)
dict_to_graph_file(mr_graph, mr_file_name)
augmented_edges = {}
# counters to keep track of convergence of MapReduce jobs
converge_count = 5
previous_count = -1
while converge_count != 0:
infile = open(mr_file_name, "r")
# uncomment to run on emr
# mr_job = max_flow.MRFlow(args=['-r', 'emr'])
mr_job = max_flow.MRFlow()
mr_job.stdin = infile
with mr_job.make_runner() as runner:
# perform iteration of MapReduce
runner.run()
# process map reduce output
out_buffer = []
for line in runner.stream_output():
# print str(counter) + ": " + line
key, value = extract_key_value(line)
if key == "A_p":
A_p = value
merge_edge_flow(augmented_edges, A_p)
else:
out_buffer.append(line)
# write map reduce output to file for next iteration
outfile = open(mr_file_name, "w")
for line in out_buffer:
key, value = extract_key_value(line)
value.append(A_p)
# value.append(1)
new_line = json.dumps(key) + "\t" + json.dumps(value) + "\n"
outfile.write(new_line)
# check for convergence
move_counts = runner.counters()[0]["move"]
if move_counts["source"] == previous_count:
converge_count -= 1
else:
converge_count = 5
previous_count = move_counts["source"]
infile.close()
outfile.close()
# augment graph based on max flow
# original_graph = dict_graph_to_python_graph(original_graph_dict)
augmented_graph = augment_graph(original_graph, augmented_edges)
# find cut
spanning_tree, preordering, postordering = depth_first_search(augmented_graph, "s")
min_cut = find_max_flow(original_graph, preordering)
return min_cut, preordering