def degree_centrality(network: Network, mode: str = 'degree') -> dict:
"""Calculates the degree centrality of all nodes.
Parameters
----------
network : Network
The :py:class:`Network` object that contains the network
mode : str
Can be chose nas 'degree', 'indegree', or 'outdegree'. Determines
whether to calculate undirected/total degrees, indegrees, or degrees
Examples
--------
Compute degree centrality in a simple network
>>> import pathpy as pp
>>> net = pp.Network(directed=True)
>>> net.add_edge('a', 'x')
>>> net.add_edge('x', 'b')
>>> c = pp.algorithms.centralities.degree_centrality(net)
>>> c['a']
1
>>> c = pp.algorithms.centralities.degree_centrality(net, mode='indegree')
>>> c['a']
0
"""
d: dict = dict()
if mode not in set(['degree', 'indegree', 'outdegree']):
LOG.error('Mode must be \'degree\', \'indegree\' or \'outdegree\'')
raise KeyError
for v in network.nodes.keys():
if mode == 'indegree':
d[v] = network.indegrees()[v]
elif mode == 'outdegree':
d[v] = network.outdegrees()[v]
else:
d[v] = network.degrees()[v]
return d
def local_clustering_coefficient(network: Network, v: str) -> float:
"""Calculates the local clustering coefficient of a node in a network.
The local clustering coefficient of any node with an (out-)degree smaller
than two is defined as zero. For all other nodes, it is defined as:
cc(c) := 2*k(i)/(d_i(d_i-1))
or
cc(c) := k(i)/(d_out_i(d_out_i-1))
in undirected and directed networks respectively.
Parameters
----------
network : Network
The network in which to calculate the local clustering coefficient
node : str
The node for which the local clustering coefficient shall be calculated
"""
lcc: float = 0.
d = network.degrees()
o = network.outdegrees()
if network.directed and o[v] >= 2 or network.directed == False and d[
v] >= 2:
k: int = 0
# compute set of closed triads
closed = closed_triads(network, v)
k = len(closed)
if network.directed:
return k / (o[v] * (o[v] - 1))
else:
return 2 * k / (d[v] * (d[v] - 1))
else:
return 0.
def degree_assortativity(network: Network,
mode: str = 'total',
weight: Weight = None) -> float:
"""Calculates the degree assortativity coefficient of a network.
Parameters
----------
network : Network
The network in which to calculate the Molloy-Reed fraction
"""
A = network.adjacency_matrix(weight=weight)
m = np.sum(A)
d = network.degrees(weight)
if network.directed and mode == 'in':
d = network.indegrees(weight)
elif network.directed and mode == 'out':
d = network.outdegrees(weight)
elif network.directed and mode == 'total':
d = network.degrees(weight)
elif not network.directed:
m = m / 2.
idx = network.nodes.index
cov: float = 0.
var: float = 0.
for i in network.nodes.keys():
for j in network.nodes.keys():
cov += (A[idx[i], idx[j]] - (d[i] * d[j]) / (2 * m)) * d[i] * d[j]
if i != j:
var -= (d[i] * d[j]) / (2 * m) * d[i] * d[j]
else:
var += (d[i] - (d[i] * d[j]) / (2 * m)) * d[i] * d[j]
return cov / var
