build.graph.KytosGraph.constrained_k_shortest_paths() - Code Metrics - Inspection of "fix: removed support for `desired_links` and fixed..." - kytos-ng/pathfinder - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Pull Request — master (#47)

by Vinicius

created 2023-05-09 21:52 UTC

KytosGraph.constrained_k_shortest_paths() B

↳ Parent: build.graph

Complexity

Conditions

Size

Total Lines	50
Code Lines	41

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	22
CRAP Score	7

Importance

Changes

Metric	Value
cc	7
eloc	41
nop	8
dl	0
loc	50
ccs	22
cts	22
cp	1
crap	7
rs	7.496
c	0
b	0
f	0

How to fix Many Parameters

"""Module Graph of kytos/pathfinder Kytos Network Application."""

# pylint: disable=too-many-arguments,too-many-locals
from itertools import combinations, islice

from kytos.core import log
from kytos.core.common import EntityStatus
from napps.kytos.pathfinder.utils import (filter_ge, filter_in, filter_le,
                                          lazy_filter, nx_edge_data_delay,
                                          nx_edge_data_priority,
                                          nx_edge_data_weight)

try:
    import networkx as nx
    from networkx.exception import NetworkXNoPath, NodeNotFound
except ImportError:
    PACKAGE = "networkx==2.5.1"
    log.error(f"Package {PACKAGE} not found. Please 'pip install {PACKAGE}'")


class KytosGraph:
    """Class responsible for the graph generation."""

    def __init__(self):
        self.graph = nx.Graph()
        self._filter_functions = {
            "ownership": lazy_filter(str, filter_in("ownership")),
            "bandwidth": lazy_filter((int, float), filter_ge("bandwidth")),
            "reliability": lazy_filter((int, float), filter_ge("reliability")),
            "priority": lazy_filter((int, float), filter_le("priority")),
            "utilization": lazy_filter((int, float), filter_le("utilization")),
            "delay": lazy_filter((int, float), filter_le("delay")),
        }
        self.spf_edge_data_cbs = {
            "hop": nx_edge_data_weight,
            "delay": nx_edge_data_delay,
            "priority": nx_edge_data_priority,
        }

    def clear(self):
        """Remove all nodes and links registered."""
        self.graph.clear()

    def update_topology(self, topology):
        """Update all nodes and links inside the graph."""
        self.graph.clear()
        self.update_nodes(topology.switches)
        self.update_links(topology.links)

    def update_nodes(self, nodes):
        """Update all nodes inside the graph."""
        for node in nodes.values():
            try:
                if node.status != EntityStatus.UP:
                    continue
                self.graph.add_node(node.id)

                for interface in node.interfaces.values():
                    if interface.status == EntityStatus.UP:
                        self.graph.add_node(interface.id)
                        self.graph.add_edge(node.id, interface.id)

            except AttributeError as err:
                raise TypeError(
                    f"Error when updating nodes inside the graph: {str(err)}"
                )

    def update_links(self, links):
        """Update all links inside the graph."""
        for link in links.values():
            if link.status == EntityStatus.UP:
                self.graph.add_edge(link.endpoint_a.id, link.endpoint_b.id)
                self.update_link_metadata(link)

    def update_link_metadata(self, link):
        """Update link metadata."""
        for key, value in link.metadata.items():
            if key not in self._filter_functions:
                continue
            endpoint_a = link.endpoint_a.id
            endpoint_b = link.endpoint_b.id
            self.graph[endpoint_a][endpoint_b][key] = value

    def get_link_metadata(self, endpoint_a, endpoint_b):
        """Return the metadata of a link."""
        return self.graph.get_edge_data(endpoint_a, endpoint_b)

    @staticmethod
    def _remove_switch_hops(circuit):
        """Remove switch hops from a circuit hops list."""
        for hop in circuit["hops"]:
            if len(hop.split(":")) == 8:
                circuit["hops"].remove(hop)

    def _path_cost(self, path, weight="hop", default_cost=1):
        """Compute the path cost given an attribute."""
        cost = 0
        for node, nbr in nx.utils.pairwise(path):
            cost += self.graph[node][nbr].get(weight, default_cost)
        return cost

    def path_cost_builder(self, paths, weight="hop", default_weight=1):
        """Build the cost of a path given a list of paths."""
        paths_acc = []
        for path in paths:
            if isinstance(path, list):
                paths_acc.append(
                    {
                        "hops": path,
                        "cost": self._path_cost(
                            path, weight=weight, default_cost=default_weight
                        ),
                    }
                )
            elif isinstance(path, dict):
                path["cost"] = self._path_cost(
                    path["hops"], weight=weight, default_cost=default_weight
                )
                paths_acc.append(path)
            else:
                raise TypeError(
                    f"type: '{type(path)}' must be be either list or dict. "
                    f"path: {path}"
                )
        return paths_acc

    def k_shortest_paths(
        self, source, destination, weight=None, k=1, graph=None
    ):
        """
        Compute up to k shortest paths and return them.

        This procedure is based on algorithm by Jin Y. Yen [1].
        Since Yen's algorithm calls Dijkstra's up to k times, the time
        complexity will be proportional to K * Dijkstra's, average
        O(K(|V| + |E|)logV), assuming it's using a heap, where V is the
        number of vertices and E number of egdes.

        References
        ----------
        .. [1] Jin Y. Yen, "Finding the K Shortest Loopless Paths in a
           Network", Management Science, Vol. 17, No. 11, Theory Series
           (Jul., 1971), pp. 712-716.
        """
        try:
            return list(
                islice(
                    nx.shortest_simple_paths(
                        graph or self.graph,
                        source,
                        destination,
                        weight=weight,
                    ),
                    k,
                )
            )
        except (NodeNotFound, NetworkXNoPath):
            return []

    def constrained_k_shortest_paths(
        self,
        source,
        destination,
        weight=None,
        k=1,
        graph=None,
        minimum_hits=None,
        **metrics,
    ):
        """Calculate the constrained shortest paths with flexibility."""
        graph = graph or self.graph
        mandatory_metrics = metrics.get("mandatory_metrics", {})
        flexible_metrics = metrics.get("flexible_metrics", {})
        first_pass_links = list(
            self._filter_links(
                graph.edges(data=True), **mandatory_metrics
            )
        )
        length = len(flexible_metrics)
        if minimum_hits is None:
            minimum_hits = 0
        minimum_hits = min(length, max(0, minimum_hits))

        paths = []
        for i in range(length, minimum_hits - 1, -1):
            for combo in combinations(flexible_metrics.items(), i):
                additional = dict(combo)
                filtered_links = self._filter_links(
                    first_pass_links, **additional
                )
                filtered_links = ((u, v) for u, v, d in filtered_links)

                for path in self.k_shortest_paths(
                    source,
                    destination,
                    weight=weight,
                    k=k,
                    graph=graph.edge_subgraph(filtered_links),
                ):
                    paths.append(
                        {
                            "hops": path,
                            "metrics": {**mandatory_metrics, **additional},
                        }
                    )
                if len(paths) == k:
                    return paths
            if paths:
                return paths
        return paths

    def _filter_links(self, links, **metrics):
        for metric, value in metrics.items():
            filter_func = self._filter_functions.get(metric, None)
            if filter_func is not None:
                try:
                    links = filter_func(value, links)
                except TypeError as err:
                    raise TypeError(
                        f"Error in {metric} value: {value} err: {err}"
                    )
        return links


1		"""Module Graph of kytos/pathfinder Kytos Network Application."""
2
3		# pylint: disable=too-many-arguments,too-many-locals
4	1	from itertools import combinations, islice
5
6	1	from kytos.core import log
7	1	from kytos.core.common import EntityStatus
8	1	from napps.kytos.pathfinder.utils import (filter_ge, filter_in, filter_le,
9		lazy_filter, nx_edge_data_delay,
10		nx_edge_data_priority,
11		nx_edge_data_weight)
12
13	1	try:
14	1	import networkx as nx
15	1	from networkx.exception import NetworkXNoPath, NodeNotFound
16		except ImportError:
17		PACKAGE = "networkx==2.5.1"
18		log.error(f"Package {PACKAGE} not found. Please 'pip install {PACKAGE}'")
19
20
21	1	class KytosGraph:
22		"""Class responsible for the graph generation."""
23
24	1	def __init__(self):
25	1	self.graph = nx.Graph()
26	1	self._filter_functions = {
27		"ownership": lazy_filter(str, filter_in("ownership")),
28		"bandwidth": lazy_filter((int, float), filter_ge("bandwidth")),
29		"reliability": lazy_filter((int, float), filter_ge("reliability")),
30		"priority": lazy_filter((int, float), filter_le("priority")),
31		"utilization": lazy_filter((int, float), filter_le("utilization")),
32		"delay": lazy_filter((int, float), filter_le("delay")),
33		}
34	1	self.spf_edge_data_cbs = {
35		"hop": nx_edge_data_weight,
36		"delay": nx_edge_data_delay,
37		"priority": nx_edge_data_priority,
38		}
39
40	1	def clear(self):
41		"""Remove all nodes and links registered."""
42	1	self.graph.clear()
43
44	1	def update_topology(self, topology):
45		"""Update all nodes and links inside the graph."""
46	1	self.graph.clear()
47	1	self.update_nodes(topology.switches)
48	1	self.update_links(topology.links)
49
50	1	def update_nodes(self, nodes):
51		"""Update all nodes inside the graph."""
52	1	for node in nodes.values():
53	1	try:
54	1	if node.status != EntityStatus.UP:
55	1	continue
56	1	self.graph.add_node(node.id)
57
58	1	for interface in node.interfaces.values():
59	1	if interface.status == EntityStatus.UP:
60	1	self.graph.add_node(interface.id)
61	1	self.graph.add_edge(node.id, interface.id)
62
63	1	except AttributeError as err:
64	1	raise TypeError(
65		f"Error when updating nodes inside the graph: {str(err)}"
66		)
67
68	1	def update_links(self, links):
69		"""Update all links inside the graph."""
70	1	for link in links.values():
71	1	if link.status == EntityStatus.UP:
72	1	self.graph.add_edge(link.endpoint_a.id, link.endpoint_b.id)
73	1	self.update_link_metadata(link)
74
75	1	def update_link_metadata(self, link):
76		"""Update link metadata."""
77	1	for key, value in link.metadata.items():
78	1	if key not in self._filter_functions:
79	1	continue
80	1	endpoint_a = link.endpoint_a.id
81	1	endpoint_b = link.endpoint_b.id
82	1	self.graph[endpoint_a][endpoint_b][key] = value
83
84	1	def get_link_metadata(self, endpoint_a, endpoint_b):
85		"""Return the metadata of a link."""
86	1	return self.graph.get_edge_data(endpoint_a, endpoint_b)
87
88	1	@staticmethod
89	1	def _remove_switch_hops(circuit):
90		"""Remove switch hops from a circuit hops list."""
91	1	for hop in circuit["hops"]:
92	1	if len(hop.split(":")) == 8:
93	1	circuit["hops"].remove(hop)
94
95	1	def _path_cost(self, path, weight="hop", default_cost=1):
96		"""Compute the path cost given an attribute."""
97	1	cost = 0
98	1	for node, nbr in nx.utils.pairwise(path):
99	1	cost += self.graph[node][nbr].get(weight, default_cost)
100	1	return cost
101
102	1	def path_cost_builder(self, paths, weight="hop", default_weight=1):
103		"""Build the cost of a path given a list of paths."""
104	1	paths_acc = []
105	1	for path in paths:
106	1	if isinstance(path, list):
107	1	paths_acc.append(
108		{
109		"hops": path,
110		"cost": self._path_cost(
111		path, weight=weight, default_cost=default_weight
112		),
113		}
114		)
115	1	elif isinstance(path, dict):
116	1	path["cost"] = self._path_cost(
117		path["hops"], weight=weight, default_cost=default_weight
118		)
119	1	paths_acc.append(path)
120		else:
121		raise TypeError(
122		f"type: '{type(path)}' must be be either list or dict. "
123		f"path: {path}"
124		)
125	1	return paths_acc
126
127	1	def k_shortest_paths(
128		self, source, destination, weight=None, k=1, graph=None
129		):
130		"""
131		Compute up to k shortest paths and return them.
132
133		This procedure is based on algorithm by Jin Y. Yen [1].
134		Since Yen's algorithm calls Dijkstra's up to k times, the time
135		complexity will be proportional to K * Dijkstra's, average
136		O(K(\|V\| + \|E\|)logV), assuming it's using a heap, where V is the
137		number of vertices and E number of egdes.
138
139		References
140		----------
141		.. [1] Jin Y. Yen, "Finding the K Shortest Loopless Paths in a
142		Network", Management Science, Vol. 17, No. 11, Theory Series
143		(Jul., 1971), pp. 712-716.
144		"""
145	1	try:
146	1	return list(
147		islice(
148		nx.shortest_simple_paths(
149		graph or self.graph,
150		source,
151		destination,
152		weight=weight,
153		),
154		k,
155		)
156		)
157	1	except (NodeNotFound, NetworkXNoPath):
158	1	return []
159
160	1	def constrained_k_shortest_paths(
161		self,
162		source,
163		destination,
164		weight=None,
165		k=1,
166		graph=None,
167		minimum_hits=None,
168		**metrics,
169		):
170		"""Calculate the constrained shortest paths with flexibility."""
171	1	graph = graph or self.graph
172	1	mandatory_metrics = metrics.get("mandatory_metrics", {})
173	1	flexible_metrics = metrics.get("flexible_metrics", {})
174	1	first_pass_links = list(
175		self._filter_links(
176		graph.edges(data=True), **mandatory_metrics
177		)
178		)
179	1	length = len(flexible_metrics)
180	1	if minimum_hits is None:
181	1	minimum_hits = 0
182	1	minimum_hits = min(length, max(0, minimum_hits))
183
184	1	paths = []
185	1	for i in range(length, minimum_hits - 1, -1):
186	1	for combo in combinations(flexible_metrics.items(), i):
187	1	additional = dict(combo)
188	1	filtered_links = self._filter_links(
189		first_pass_links, **additional
190		)
191	1	filtered_links = ((u, v) for u, v, d in filtered_links)
		0 ignored issues – show introduced 2021-11-30 20:18 UTC by Report Bug Copy Issue Report The variable `v` does not seem to be defined for all execution paths. Loading history... introduced 2021-11-30 20:18 UTC by Report Bug Copy Issue Report The variable `u` does not seem to be defined for all execution paths. Loading history...
192	1	for path in self.k_shortest_paths(
193		source,
194		destination,
195		weight=weight,
196		k=k,
197		graph=graph.edge_subgraph(filtered_links),
198		):
199	1	paths.append(
200		{
201		"hops": path,
202		"metrics": {mandatory_metrics, additional},
203		}
204		)
205	1	if len(paths) == k:
206	1	return paths
207	1	if paths:
208	1	return paths
209	1	return paths
210
211	1	def _filter_links(self, links, **metrics):
212	1	for metric, value in metrics.items():
213	1	filter_func = self._filter_functions.get(metric, None)
214	1	if filter_func is not None:
215	1	try:
216	1	links = filter_func(value, links)
217	1	except TypeError as err:
218	1	raise TypeError(
219		f"Error in {metric} value: {value} err: {err}"
220		)
221		return links
222

kytos-ng / pathfinder

Pull Request — master (#47)

KytosGraph.constrained_k_shortest_paths() B

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