def __init__(self, mode="directed"):
'''
Selects (un)directed graph mode.
'''
self._mode = mode if mode == "directed" else "undirected"
self._adjlist = AdjacencyList()
log.info("running in mode: {}".format(self._mode))
def test_adjacency_matrix(self):
for table in [
# no edges
([],[],[[]]),
(["a"], [], [ [inf] ]),
(["a","b"], [], [ [inf]*2, [inf]*2 ]),
(["a","b","c"], [], [ [inf]*3, [inf]*3, [inf]*3 ]),
# with edges (1 node)
(["a"], [("a","a",1)], [ [1] ]),
(["a"], [("a","a",2)], [ [2] ]),
# with edges (2 nodes)
(["a","b"], [("a","a",1)], [ [1,inf], [inf,inf] ]),
(["a","b"], [("a","a",1),("a","b",2)], [ [1,2], [inf,inf] ]),
(["a","b"], [("a","a",1),("a","b",2),("b","a",3)], [ [1,2], [3,inf] ]),
(["a","b"], [("a","a",1),("a","b",2),("b","a",3),("b","b",4)], [ [1,2], [3,4] ]),
(["a","b"], [("a","b",2),("b","a",3),("b","b",4)], [ [inf,2], [3,4] ]),
(["a","b"], [("b","a",3),("b","b",4)], [ [inf,inf], [3,4] ]),
(["a","b"], [("b","b",4)], [ [inf,inf], [inf,4] ]),
# with edges (3 nodes)
(["a","b","c"], [("a","a",9),("b","b",2),("c","c",13)], [ [9,inf,inf], [inf,2,inf], [inf,inf,13] ]),
(["a","b","c"], [("a","a",9),("a","c",1),("b","b",2),("c","a",7),("c","c",13)], [ [9,inf,1], [inf,2,inf], [7,inf,13] ]),
# with edges (4 nodes)
(["a","b","c","d"], [("a","b",1),("b","a",4),("b","d",2),("c","c",11),("d","a",3),("d","b",1)], [ [inf,1,inf,inf], [4,inf,inf,2], [inf,inf,11,inf], [3,1,inf,inf] ]),
]:
in_nodes, in_edges, want = table
l = AdjacencyList()
for name in in_nodes:
l = l.add_node(name)
for (src, dst, weight) in in_edges:
l = l.add_edge(src, dst, weight)
self.assertEqual(l.adjacency_matrix(), want, "Added nodes {}, added edges {}".format(in_nodes, in_edges))
def test_edge_cardinality(self):
for table in [
([], [], 0),
(["a"], [], 0),
(["a","b"], [], 0),
(["a"], [("a","a")], 1),
(["a","b"], [("a","a")], 1),
(["a","b"], [("a","a"),("a","b")], 2),
(["a","b"], [("a","a"),("b","a")], 2),
(["a","b"], [("a","a"),("b","b")], 2),
(["a","b"], [("a","a"),("a","b"),("b","a")], 3),
(["a","b"], [("a","a"),("a","b"),("b","b")], 3),
(["a","b"], [("a","a"),("b","a"),("b","b")], 3),
(["a","b"], [("a","a"),("a","b"),("b","a"),("b","b")], 4),
(["a","b","c"], [("a","b"),("b","b"),("b","c"),("c","a"),("c","c")], 5),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a"),("c","c")], 6),
(["a","b","c"], [("a","a"),("a","b"),("a","c"),("b","b"),("b","c"),("c","a"),("c","c")], 7),
(["a","b","c"], [("a","a"),("a","b"),("a","c"),("b","a"),("b","b"),("b","c"),("c","a"),("c","c")], 8),
(["a","b","c"], [("a","a"),("a","b"),("a","c"),("b","a"),("b","b"),("b","c"),("c","a"),("c","b"),("c","c")], 9),
]:
in_nodes, in_edges, want = table
l = AdjacencyList()
for name in in_nodes:
l = l.add_node(name)
for (src, dst) in in_edges:
l = l.add_edge(src, dst)
self.assertEqual(l.edge_cardinality(), want, "Added nodes {}, added edges {}".format(in_nodes, in_edges))
def test_find_edge(self):
for table in [
([], [], ("a","a"), False),
([], [], ("a","b"), False),
([], [], ("b","a"), False),
(["a"], [], ("a","a"), False),
(["a"], [], ("a","b"), False),
(["a"], [], ("b","a"), False),
(["a"], [("a","a")], ("a","a"), True),
(["a"], [("a","a")], ("a","b"), False),
(["a"], [("a","a")], ("b","a"), False),
(["a","b"], [], ("a","a"), False),
(["a","b"], [], ("a","b"), False),
(["a","b"], [], ("b","a"), False),
(["a","b"], [("a","b"),("b","b")], ("a","a"), False),
(["a","b"], [("a","b"),("b","b")], ("a","b"), True),
(["a","b"], [("a","b"),("b","b")], ("b","b"), True),
(["a","b"], [("a","b"),("b","b")], ("b","a"), False),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("a","a"), True),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("a","b"), True),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("a","c"), False),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("b","a"), False),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("b","b"), True),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("b","c"), True),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("c","a"), True),
(["a","b","c"], [("a","a"),("a","b"),("b","b"),("b","c"),("c","a")], ("c","b"), False),
]:
in_nodes, in_edges, target, want = table
l = AdjacencyList()
for name in in_nodes:
l = l.add_node(name)
for (src, dst) in in_edges:
l = l.add_edge(src, dst)
self.assertEqual(l.find_edge(target[0], target[1]), want, "Added nodes {}, added edges {}, find edge {}".format(in_nodes, in_edges, target))
def test_is_empty(self):
for table in [
([], True),
(["a"], False),
(["a","b"], False),
(["b","a"], False),
]:
in_sequence, want = table
l = AdjacencyList()
for name in in_sequence:
l = l.add_node(name)
self.assertEqual(l.is_empty(), want, "Added nodes {}".format(in_sequence))
def test_node_cardinality(self):
for table in [
([], 0),
(["a"], 1),
(["a","b"], 2),
(["a","b","c"], 3),
(["a","b","c","d"], 4),
]:
in_sequence, want = table
l = AdjacencyList()
for name in in_sequence:
l = l.add_node(name)
self.assertEqual(l.node_cardinality(), want, "Added nodes {}".format(in_sequence))
def test_add_node(self):
for in_sequence in [
([]),
(["a"]),
(["a","b"]),
(["b","a"]),
(["a","b","c"]),
(["a","c","b"]),
(["b","a","c"]),
(["b","c","a"]),
(["c","a","b"]),
(["c","b","a"]),
]:
want = sorted(in_sequence)
l = AdjacencyList()
for name in in_sequence:
l = l.add_node(name)
self.assertEqual(l.list_nodes(), want, "Added nodes {}".format(in_sequence))
def test_find_node(self):
for table in [
([], "a", False),
(["a"], "a", True),
(["a"], "b", False),
(["a"], "B", False),
(["a","b"], "a", True),
(["a","b"], "b", True),
(["a","b"], "c", False),
(["a","b"], "C", False),
(["a","b","c"], "a", True),
(["a","b","c"], "b", True),
(["a","b","c"], "c", True),
(["a","b","c"], "d", False),
(["a","b","c"], "D", False),
]:
in_sequence, target, want = table
l = AdjacencyList()
for name in in_sequence:
l = l.add_node(name)
self.assertEqual(l.find_node(target), want, "Added nodes {}, find node '{}'".format(in_sequence, target))
def test_delete_edges(self):
for table in [
# empty
([], [], "a", []),
# 1 node
(["a"], [], "a", []),
(["a"], [("a","a",1)], "a", []),
#(["a"], [("a","a",1)], "b", [("a","a",1)]),
# 2 nodes
(["a","b"], [("a","a",1),("a","b",1),("b","a",1),("b","b",1)], "a", [("a","b",1),("b","b",1)]),
(["a","b"], [("a","a",1),("a","b",1),("b","a",1),("b","b",1)], "b", [("a","a",1),("b","a",1)]),
(["a","b"], [("a","a",1),("a","b",1),("b","a",1),("b","b",1)], "c", [("a","a",1),("a","b",1),("b","a",1),("b","b",1)]),
# 3 nodes
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1),("c","c",1)], "a", [("a","b",1),("a","c",1),("b","b",1),("b","c",1),("c","b",1),("c","c",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1),("c","c",1)], "b", [("a","a",1),("a","c",1),("b","a",1),("b","c",1),("c","a",1),("c","c",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1),("c","c",1)], "c", [("a","a",1),("a","b",1),("b","a",1),("b","b",1),("c","a",1),("c","b",1)]),
]:
in_nodes, in_edges, target, want = table
l = AdjacencyList()
for name in in_nodes:
l = l.add_node(name)
for (src, dst, weight) in in_edges:
l = l.add_edge(src, dst, weight)
l = l.delete_edges(target)
self.assertEqual(l.list_edges(), want, "Added nodes {}, added edges {}, deleted edges towards node {}".format(in_nodes, in_edges, target))
def test_delete_node(self):
for table in [
([], "a", []),
(["a"], "a", []),
(["a"], "b", ["a"]),
(["a"], "B", ["a"]),
(["a","b"], "a", ["b"]),
(["a","b"], "b", ["a"]),
(["a","b"], "c", ["a","b"]),
(["a","b"], "C", ["a","b"]),
(["a","b","c"], "a", ["b","c"]),
(["a","b","c"], "b", ["a","c"]),
(["a","b","c"], "c", ["a","b"]),
(["a","b","c"], "d", ["a","b","c"]),
(["a","b","c"], "D", ["a","b","c"]),
]:
in_sequence, target, want = table
l = AdjacencyList()
for name in in_sequence:
l = l.add_node(name)
l = l.delete_node(target)
self.assertEqual(l.list_nodes(), want, "Added nodes {}, deleted '{}'".format(in_sequence, target))
def test_add_edge_update(self):
for table in [
# 1 node
(["a"], [], []),
(["a"], [("a","a",1),("a","a",2)], [("a","a",2)]),
# 2 nodes
(["a","b"], [("a","a",1), ("a","a",2)], [("a","a",2)]),
(["a","b"], [("a","a",1), ("a","b",1),("b","a",1), ("a","a",2)], [("a","a",2),("a","b",1),("b","a",1)]),
(["a","b"], [("a","a",1), ("a","b",1),("b","a",1), ("a","b",2)], [("a","a",1),("a","b",2),("b","a",1)]),
(["a","b"], [("a","a",1), ("a","b",1),("b","a",1), ("b","a",2)], [("a","a",1),("a","b",1),("b","a",2)]),
# 3 nodes
(["a","b","c"], [("a","b",1),("b","b",1),("b","c",1),("a","b",2)], [("a","b",2),("b","b",1),("b","c",1)]),
(["a","b","c"], [("a","b",1),("b","b",1),("b","c",1),("b","b",2)], [("a","b",1),("b","b",2),("b","c",1)]),
(["a","b","c"], [("a","b",1),("b","b",1),("b","c",1),("b","c",2)], [("a","b",1),("b","b",1),("b","c",2)]),
]:
in_nodes, in_edges, want = table
l = AdjacencyList()
for name in in_nodes:
l = l.add_node(name)
for (src, dst, weight) in in_edges:
l = l.add_edge(src, dst, weight)
self.assertEqual(l.list_edges(), want, "Added nodes {}, added edges {}".format(in_nodes, in_edges))
def test_add_edge(self):
for table in [
# no nodes
([], [("a","a",1)], []),
([], [("a","b",1)], []),
([], [("b","a",1)], []),
# 1 node
(["a"], [], []),
(["a"], [("a","a",1)], [("a","a",1)]),
(["a"], [("a","b",1)], []),
(["a"], [("b","a",1)], []),
# 2 nodes
(["a","b"], [], []),
(["a","b"], [("a","a",1)], [("a","a",1)]),
(["a","b"], [("a","a",1), ("a","a",1)], [("a","a",1)]),
(["a","b"], [("a","a",1), ("a","b",1)], [("a","a",1),("a","b",1)]),
(["a","b"], [("a","a",1), ("a","b",1),("b","a",1)], [("a","a",1),("a","b",1),("b","a",1)]),
# 3 nodes
(["a","b","c"], [], []),
(["a","b","c"], [("a","a",1)], [("a","a",1)]),
(["a","b","c"], [("a","a",1),("a","b",1)], [("a","a",1),("a","b",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1)], [("a","a",1),("a","b",1),("a","c",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1)], [("a","a",1),("a","b",1),("a","c",1),("b","a",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1)], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1)], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1)], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1)], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1)]),
(["a","b","c"], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1),("c","c",1)], [("a","a",1),("a","b",1),("a","c",1),("b","a",1),("b","b",1),("b","c",1),("c","a",1),("c","b",1),("c","c",1)]),
]:
in_nodes, in_edges, want = table
for _ in range(10):
random.Random(1337).shuffle(in_edges)
l = AdjacencyList()
for name in in_nodes:
l = l.add_node(name)
for (src, dst, weight) in in_edges:
l = l.add_edge(src, dst, weight)
self.assertEqual(l.list_edges(), want, "Added nodes {}, added edges {}".format(in_nodes, in_edges))
class TerminalUI:
def __init__(self, mode="directed"):
'''
Selects (un)directed graph mode.
'''
self._mode = mode if mode == "directed" else "undirected"
self._adjlist = AdjacencyList()
log.info("running in mode: {}".format(self._mode))
def run(self):
'''
Provides a terminal-based UI to perform graph operations.
'''
self.display_menu()
while True:
opt, err = self.get_choice()
if err is not None:
self.display_error(err)
continue
if opt == "m":
self.display_menu()
elif opt == "v":
self.display_graph()
elif opt == "a":
self.add_node()
elif opt == "b":
self.add_edge()
elif opt == "d":
self.delete_node()
elif opt == "r":
self.delete_edge()
elif opt == "f":
self.find_node()
elif opt == "g":
self.find_edge()
elif opt == "D":
self.dijkstra()
elif opt == "F":
self.floyd()
elif opt == "W":
self.warshall()
elif opt == "P":
self.prim()
elif opt == "q":
break
else:
log.error("menu case '{}' is missing, aborting".format(opt))
return 1
def menu_options(self):
'''
Returns a list of printable menu options. Blank entries are interpreted
as new lines, and single characters before the colon as hotkeys.
'''
return [
"m: menu",
"v: view",
"q: quit",
"",
"a: add node",
"b: add edge",
"",
"d: delete node",
"r: delete edge",
"",
"f: find node",
"g: find edge",
"",
"W: Warshall",
"F: Floyd",
"D: Dijkstra",
"P: Prim",
]
def display_menu(self):
'''
Shows a menu which is encapsulated between a top rule and a bottom rule.
'''
print(self.menu_rule("top", self.menu_width()))
for opt in self.menu_options():
print("\t{}".format(opt))
print(self.menu_rule("bot", self.menu_width()))
def menu_rule(self, pos, width):
'''
Returns a horizontal line using stars or tildes.
'''
return ("*" if pos == "top" else "~") * width
def menu_width(self):
'''
Returns the menu width.
'''
return 32
def menu_hotkeys(self):
'''
Returns a list of symbols that the menu defined as valid hotkeys.
'''
opts = self.menu_options()
return [o.split(":")[0] for o in opts if len(o.split(":")[0]) == 1]
def get_choice(self):
'''
Attempts to read a valid menu option from the user.
'''
c, err = self.get_char("menu")
if err is not None:
return None, err
if c not in self.menu_hotkeys():
return None, "invalid choice"
return c, None
def get_node(self, msg, want):
'''
Attempts to read a valid node name from the user. If `want` is False
(True), an error is returned if the entered node is a (non-)member.
'''
name, err = self.get_char(msg)
if err is not None:
return None, err
if want != self._adjlist.find_node(name):
return None, "node '{}' is a {}member".format(
name, "non-" if want else "")
return name, None
def get_char(self, message):
'''
Writes a message to stdout and waits for one-character from stdin.
'''
buf = input("{}> ".format(message))
if len(buf) != 1:
return None, "invalid input (not a single character)"
return buf, None
def get_int(self, message):
'''
Writes a message to stdout and waits for an integer from stdin.
'''
buf = input("{}> ".format(message))
try:
return int(buf), None
except ValueError:
return None, "invalid input (not an integer)"
def get_weight(self, message, low, high):
'''
Writes a message to stdout and waits for an integer in [low,high].
'''
weight, err = self.get_int(message)
if err is not None:
return None, err
if weight < low or weight > high:
return None, "invalid input (weight must be in [{},{}])".format(
low, high)
return weight, None
def display_graph(self):
'''
Displays graph info.
'''
if self._adjlist.is_empty():
self.display_empty()
return
nodes = self._adjlist.list_nodes()
log.debug("all nodes: {}".format(nodes))
log.debug("all edges: {}".format(self._adjlist.list_edges()))
self.display_matrix_head(nodes)
self.display_matrix_data(nodes, self._adjlist.adjacency_matrix())
self.display_cardinality()
def add_node(self):
'''
Let the user add a node to the graph.
'''
name, err = self.get_node("Enter node name", False)
if err is not None:
self.display_error(err)
return
self._adjlist = self._adjlist.add_node(name)
def delete_node(self):
'''
Let the user delete add a node from the graph.
'''
name, err = self.get_node("Enter node name", True)
if err is not None:
self.display_error(err)
return
self._adjlist = self._adjlist.delete_edges(name)
self._adjlist = self._adjlist.delete_node(name)
def add_edge(self):
'''
Let the user add an edge to the graph.
'''
from_node, err = self.get_node("Enter from node", True)
if err is not None:
self.display_error(err)
return
to_node, err = self.get_node("Enter to node", True)
if err is not None:
self.display_error(err)
return
weight, err = self.get_weight("Enter weight", 1, 99)
if err is not None:
self.display_error(err)
return
self.adj_list = self._adjlist.add_edge(from_node, to_node, weight)
if self._mode == "undirected":
self._adjlist = self._adjlist.add_edge(to_node, from_node, weight)
def delete_edge(self):
'''
Let the user delete an edge from the graph.
'''
from_node, err = self.get_node("Enter from node", True)
if err is not None:
self.display_error(err)
return
to_node, err = self.get_node("Enter to node", True)
if err is not None:
self.display_error(err)
return
if not self._adjlist.find_edge(from_node, to_node):
self.display_error("edge ({},{}) is non-member".format(
from_node, to_node))
return
self._adjlist = self._adjlist.delete_edge(from_node, to_node)
if self._mode == "undirected":
self._adjlist = self._adjlist.delete_edge(to_node, from_node)
def find_node(self):
'''
Let the user search for a node in the graph.
'''
name, err = self.get_char("Enter node name")
if err is not None:
self.display_error(err)
return
if self._adjlist.find_node(name):
self.display_member_node(name)
else:
self.display_nonmember_node(name)
def find_edge(self):
'''
Let the user search for an edge in the graph.
'''
from_node, err = self.get_char("Enter from node")
if err is not None:
self.display_error(err)
return
to_node, err = self.get_char("Enter to node")
if err is not None:
self.display_error(err)
return
if self._adjlist.find_edge(from_node, to_node):
self.display_member_edge(from_node, to_node)
else:
self.display_nonmember_edge(from_node, to_node)
def warshall(self):
'''
Run Warshall's algorithm.
'''
if self._adjlist.is_empty():
self.display_error("graph is empty")
return
nodes = self._adjlist.list_nodes()
self.display_matrix_head(nodes)
self.display_matrix_data(nodes, warshall(self._adjlist))
def floyd(self):
'''
Run Floyds's algorithm.
'''
if self._adjlist.is_empty():
self.display_error("graph is empty")
return
nodes = self._adjlist.list_nodes()
self.display_matrix_head(nodes)
self.display_matrix_data(nodes, floyd(self._adjlist))
def dijkstra(self):
'''
Run Dijkstra's algorithm.
'''
if self._adjlist.is_empty():
self.display_error("graph is empty")
return
start_node, err = self.get_node("Enter start node", True)
if err is not None:
self.display_error(err)
return
dist, prev = dijkstra(self._adjlist, start_node)
self.display_sequence_head(self._adjlist.list_nodes())
self.display_sequence_data([
("distance", dist, None),
("previous", prev, None),
])
def prim(self):
'''
Run Prim's algorithm.
'''
if self._mode == "directed":
self.error("invalid graph mode")
return
if self._adjlist.is_empty():
self.display_error("graph is empty")
return
start_node, err = self.get_node("Enter start node", True)
if err is not None:
self.display_error(err)
return
lowcost, closest = prim(self._adjlist, start_node)
self.display_sequence_head(self._adjlist.list_nodes())
self.display_sequence_data([
("lowcost", lowcost, None),
("closest", closest, None),
])
self.display_mst_sum(lowcost)
def display_mst_sum(self, lowcost):
mst_sum = sum([v for v in lowcost if v is not None and v != inf])
print("\tMST sum: {}\n".format(mst_sum))
def display_empty(self):
print("\n\tGraph is empty\n")
def display_member_node(self, name):
print("\tNode {} is a member".format(name))
def display_nonmember_node(self, name):
print("\tNode {} is a non-member".format(name))
def display_member_edge(self, from_node, to_node):
print("\tEdge ({},{}) is a member".format(from_node, to_node))
def display_nonmember_edge(self, from_node, to_node):
print("\tEdge ({},{}) is a non-member".format(from_node, to_node))
def display_sequence_head(self, nodes):
print("\n {: ^8}#".format(""), end="")
for node in nodes:
print(" {: ^3} ".format(node), end="")
print("\n ========#" + "=" * 5 * len(nodes))
def display_sequence_data(self, data):
for (name, sequence, star_val) in data:
print(" {: >8}#".format(name), end="")
for v in sequence:
print(" {: ^3} ".format("*" if v == star_val else v), end="")
print("")
print("")
def display_matrix_head(self, nodes):
print("\n {: ^3}|".format(""), end="")
for node in nodes:
print(" {: ^3} ".format(node), end="")
print("\n----+" + "-" * 5 * len(nodes))
def display_matrix_data(self, nodes, matrix):
for name, row in zip(nodes, matrix):
print(" {: >3}|".format(name), end="")
for col in row:
print(" {: ^3} ".format("*" if col == inf else col), end="")
print("")
print("")
def display_cardinality(self):
node_cardinality = self._adjlist.node_cardinality()
edge_cardinality = self._adjlist.edge_cardinality()
if self._mode == "undirected":
self_loops = self._adjlist.self_loops()
edge_cardinality = int((edge_cardinality - self_loops) / 2 +
self_loops)
print("node cardinality: {}".format(node_cardinality))
print("edge cardinality: {}".format(edge_cardinality))
print("")
def display_error(self, err):
print("error> {}".format(err))
def prim(adjlist, start_node):
'''
Returns the result of running Prim's algorithm as two N-length lists:
1) lowcost l: here, l[i] contains the weight of the cheapest edge to connect
the i:th node to the minimal spanning tree that started at `start_node`.
2) closest c: here, c[i] contains the node name that the i:th node's
cheapest edge orignated from.
If the index i refers to the start node, set the associated values to None.
Pre: adjlist is setup as an undirected graph and start_node is a member.
=== Example ===
Suppose that we have the following adjacency matrix:
a b c
-+-----
a|* 1 3
b|1 * 1
c|3 1 *
For start node "a", the expected output would then be:
l: [ None, 1, 1]
c: [ None, 'a', 'b' ]
'''
#log.info("TODO: prim()")
print("nEW")
connected = [start_node]
tree = AdjacencyList() # keeps track of added nodes
tree.add_node(start_node)
# create initial edge and node
while are_unconnected(adjlist, connected):
curr_edge = Edge(
weight=inf) # will be overridden by first legible node
nod = adjlist
while not nod.is_empty(): # find currently node with shortest edge
edg = nod.edges()
while not edg.is_empty(): # find best edge in node
if not edg.dst() in connected and edg.weight(
) < curr_edge.weight() and edg.dst() != nod.name():
# better edge found, saving
curr_node = nod
curr_edge = edg
edg = edg.tail()
nod = nod.tail()
print("edge to {} with weight {} from {}".format(
curr_edge.dst(), curr_edge.weight(), curr_node.name()))
# shortest edge found, find the node in the parallell tre
nud = tree
while not nud.is_empty():
if nud.name() == curr_node.name():
nud.edges().add(curr_edge.dst(), curr_edge.weight())
nud = nud.tail()
tree.add_node(curr_edge.dst())
# find corresponding node for undirectional edge
"""
nad = tree
while not nad.is_empty():
if nad.name() == curr_edge.dst():
nad.edges().add(curr_node.name(), curr_edge.weight())
nad = nad.tail()
"""
connected.append(curr_edge.dst())
input()
print(connected)
print(connected)
n = adjlist.node_cardinality()
l = [inf] * n
c = [None] * n
nodelist = adjlist.list_nodes()
for index, item in enumerate(nodelist):
if not item in connected:
l[index] = inf
c[index] = None
continue
elif item == start_node:
l[index] = None
c[index] = None
continue
nad = tree
while not nad.is_empty():
edg = nad.edges()
while not edg.is_empty():
l[nodelist.index(edg.dst())] = edg.weight()
c[nodelist.index(edg.dst())] = nad.name()
edg = edg.tail()
nad = nad.tail()
print("prim prom")
print(l)
print("--")
print(c)
return l, c
