def test_dirichlet_energy(self, n_vertices=100):
r"""The Dirichlet energy is defined as the norm of the gradient."""
signal = np.random.RandomState(42).uniform(size=n_vertices)
for lap_type in ['combinatorial', 'normalized']:
graph = graphs.BarabasiAlbert(n_vertices)
graph.compute_differential_operator()
energy = graph.dirichlet_energy(signal)
grad_norm = np.sum(graph.grad(signal)**2)
np.testing.assert_allclose(energy, grad_norm)
def test_networkx_signal_export(self):
graph = graphs.BarabasiAlbert(N=100, seed=42)
rs = np.random.RandomState(42)
signal1 = rs.normal(size=graph.N)
signal2 = rs.normal(size=graph.N)
graph.set_signal(signal1, "signal1")
graph.set_signal(signal2, "signal2")
graph_nx = graph.to_networkx()
for i in range(graph.N):
self.assertEqual(graph_nx.node[i]["signal1"], signal1[i])
self.assertEqual(graph_nx.node[i]["signal2"], signal2[i])
# invalid signal type
graph = graphs.Path(3)
graph.set_signal(np.array(['a', 'b', 'c']), 'sig')
self.assertRaises(ValueError, graph.to_networkx)
def __init__(self,
n_nodes,
ux,
spectral_profile,
type_graph="erdos",
type_noise="gaussian",
save_history=True,
seed=None,
**kargs):
####### The algorithm asks the user a spectral_profile for the Graph filter that will be applied
### to white noise so the output signal is stationary with respect to the graph structure.
#### This section initialize the structure of the graph signal
### Input
# n_nodes=number of nodes
# ux= mean of the signal
# spectral_profile= a function generating the power spectral density of the sygnal.
# type_graph=available graph model (erdos,euclidean,barabasi_albert)
# type_noise = distribution of the noise (gaussian,uniform) that will be used to ge
self.n_nodes = n_nodes
self.type_graph = type_graph
self.type_noise = type_noise
self.ux = ux
self.spectral_profile = spectral_profile
self.seed = seed
if type_graph == "erdos":
self.G = graphs.ErdosRenyi(self.n_nodes,
kargs['p'],
seed=self.seed)
self.G.set_coordinates()
if type_graph == "barabasi_albert":
self.G = graphs.BarabasiAlbert(self.n_nodes,
m=kargs['m'],
m0=kargs['m'],
seed=self.seed)
self.G.set_coordinates()
if type_graph == "Minnesota":
self.G = graphs.Minnesota()
self.generate_fourier()
self.generate_filter()