def connected_components(graph):
"""
Find the connected components of a graph. Each node will be assigned a
value, indicating the component that it belongs to.
Parameters:
- - - - -
graph : adjacency matrix of graph
While there is a vertex that is not assigned to a component, run bread
first search, starting from one of the unassigned vertices. For each
traversal, assign all visited vertices to the same component.
"""
try:
[x,y] = graph.shape
except:
raise ValueError
nodes = graph.shape[0]
components = -1*np.ones((nodes,))
c = 0
while np.any(components == -1):
source = np.where(components == -1)[0][0]
[parents,visited] = traversal.bfs(graph,source=source)
components[np.where(visited)] = c
c += 1
return [c,components]
def is_connected(graph):
"""
Determine if graph is connected.
Parameters:
- - - - -
graph : adjacency matrix of graph.
"""
[parents,visited] = traversal.bfs(graph)
return np.any(visited < 1)
def testTwoNodes(self):
self.g.addEdge(1, 2)
self.assertEqual(traversal.bfs(self.g, 1), [1, 2])
self.assertEqual(traversal.bfs(self.g, 2), [2])
def testSingleNode(self):
self.g.addEdge(1, None)
self.assertEqual(traversal.bfs(self.g, 1), [1])
def testStartNotInGraph(self):
self.g.addEdge(1, 2)
self.assertEqual(traversal.bfs(self.g, 4), [])