1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
|
"""Node assortativity coefficients and correlation measures.
"""
from networkx.algorithms.assortativity.mixing import (
degree_mixing_matrix,
attribute_mixing_matrix,
numeric_mixing_matrix,
)
from networkx.algorithms.assortativity.pairs import node_degree_xy
__all__ = [
"degree_pearson_correlation_coefficient",
"degree_assortativity_coefficient",
"attribute_assortativity_coefficient",
"numeric_assortativity_coefficient",
]
def degree_assortativity_coefficient(G, x="out", y="in", weight=None, nodes=None):
"""Compute degree assortativity of graph.
Assortativity measures the similarity of connections
in the graph with respect to the node degree.
Parameters
----------
G : NetworkX graph
x: string ('in','out')
The degree type for source node (directed graphs only).
y: string ('in','out')
The degree type for target node (directed graphs only).
weight: string or None, optional (default=None)
The edge attribute that holds the numerical value used
as a weight. If None, then each edge has weight 1.
The degree is the sum of the edge weights adjacent to the node.
nodes: list or iterable (optional)
Compute degree assortativity only for nodes in container.
The default is all nodes.
Returns
-------
r : float
Assortativity of graph by degree.
Examples
--------
>>> G = nx.path_graph(4)
>>> r = nx.degree_assortativity_coefficient(G)
>>> print(f"{r:3.1f}")
-0.5
See Also
--------
attribute_assortativity_coefficient
numeric_assortativity_coefficient
degree_mixing_dict
degree_mixing_matrix
Notes
-----
This computes Eq. (21) in Ref. [1]_ , where e is the joint
probability distribution (mixing matrix) of the degrees. If G is
directed than the matrix e is the joint probability of the
user-specified degree type for the source and target.
References
----------
.. [1] M. E. J. Newman, Mixing patterns in networks,
Physical Review E, 67 026126, 2003
.. [2] Foster, J.G., Foster, D.V., Grassberger, P. & Paczuski, M.
Edge direction and the structure of networks, PNAS 107, 10815-20 (2010).
"""
if nodes is None:
nodes = G.nodes
degrees = set([d for n, d in G.degree(nodes, weight=weight)])
mapping = {d: i for i, d, in enumerate(degrees)}
M = degree_mixing_matrix(G, x=x, y=y, nodes=nodes, weight=weight, mapping=mapping)
return numeric_ac(M, mapping=mapping)
def degree_pearson_correlation_coefficient(G, x="out", y="in", weight=None, nodes=None):
"""Compute degree assortativity of graph.
Assortativity measures the similarity of connections
in the graph with respect to the node degree.
This is the same as degree_assortativity_coefficient but uses the
potentially faster scipy.stats.pearsonr function.
Parameters
----------
G : NetworkX graph
x: string ('in','out')
The degree type for source node (directed graphs only).
y: string ('in','out')
The degree type for target node (directed graphs only).
weight: string or None, optional (default=None)
The edge attribute that holds the numerical value used
as a weight. If None, then each edge has weight 1.
The degree is the sum of the edge weights adjacent to the node.
nodes: list or iterable (optional)
Compute pearson correlation of degrees only for specified nodes.
The default is all nodes.
Returns
-------
r : float
Assortativity of graph by degree.
Examples
--------
>>> G = nx.path_graph(4)
>>> r = nx.degree_pearson_correlation_coefficient(G)
>>> print(f"{r:3.1f}")
-0.5
Notes
-----
This calls scipy.stats.pearsonr.
References
----------
.. [1] M. E. J. Newman, Mixing patterns in networks
Physical Review E, 67 026126, 2003
.. [2] Foster, J.G., Foster, D.V., Grassberger, P. & Paczuski, M.
Edge direction and the structure of networks, PNAS 107, 10815-20 (2010).
"""
import scipy as sp
import scipy.stats # call as sp.stats
xy = node_degree_xy(G, x=x, y=y, nodes=nodes, weight=weight)
x, y = zip(*xy)
return sp.stats.pearsonr(x, y)[0]
def attribute_assortativity_coefficient(G, attribute, nodes=None):
"""Compute assortativity for node attributes.
Assortativity measures the similarity of connections
in the graph with respect to the given attribute.
Parameters
----------
G : NetworkX graph
attribute : string
Node attribute key
nodes: list or iterable (optional)
Compute attribute assortativity for nodes in container.
The default is all nodes.
Returns
-------
r: float
Assortativity of graph for given attribute
Examples
--------
>>> G = nx.Graph()
>>> G.add_nodes_from([0, 1], color="red")
>>> G.add_nodes_from([2, 3], color="blue")
>>> G.add_edges_from([(0, 1), (2, 3)])
>>> print(nx.attribute_assortativity_coefficient(G, "color"))
1.0
Notes
-----
This computes Eq. (2) in Ref. [1]_ , (trace(M)-sum(M^2))/(1-sum(M^2)),
where M is the joint probability distribution (mixing matrix)
of the specified attribute.
References
----------
.. [1] M. E. J. Newman, Mixing patterns in networks,
Physical Review E, 67 026126, 2003
"""
M = attribute_mixing_matrix(G, attribute, nodes)
return attribute_ac(M)
def numeric_assortativity_coefficient(G, attribute, nodes=None):
"""Compute assortativity for numerical node attributes.
Assortativity measures the similarity of connections
in the graph with respect to the given numeric attribute.
Parameters
----------
G : NetworkX graph
attribute : string
Node attribute key.
nodes: list or iterable (optional)
Compute numeric assortativity only for attributes of nodes in
container. The default is all nodes.
Returns
-------
r: float
Assortativity of graph for given attribute
Examples
--------
>>> G = nx.Graph()
>>> G.add_nodes_from([0, 1], size=2)
>>> G.add_nodes_from([2, 3], size=3)
>>> G.add_edges_from([(0, 1), (2, 3)])
>>> print(nx.numeric_assortativity_coefficient(G, "size"))
1.0
Notes
-----
This computes Eq. (21) in Ref. [1]_ , for the mixing matrix
of the specified attribute.
References
----------
.. [1] M. E. J. Newman, Mixing patterns in networks
Physical Review E, 67 026126, 2003
"""
if nodes is None:
nodes = G.nodes
vals = set(G.nodes[n][attribute] for n in nodes)
mapping = {d: i for i, d, in enumerate(vals)}
M = attribute_mixing_matrix(G, attribute, nodes, mapping)
return numeric_ac(M, mapping)
def attribute_ac(M):
"""Compute assortativity for attribute matrix M.
Parameters
----------
M : numpy.ndarray
2D ndarray representing the attribute mixing matrix.
Notes
-----
This computes Eq. (2) in Ref. [1]_ , (trace(e)-sum(e^2))/(1-sum(e^2)),
where e is the joint probability distribution (mixing matrix)
of the specified attribute.
References
----------
.. [1] M. E. J. Newman, Mixing patterns in networks,
Physical Review E, 67 026126, 2003
"""
if M.sum() != 1.0:
M = M / M.sum()
s = (M @ M).sum()
t = M.trace()
r = (t - s) / (1 - s)
return r
def numeric_ac(M, mapping):
# M is a numpy matrix or array
# numeric assortativity coefficient, pearsonr
import numpy as np
if M.sum() != 1.0:
M = M / float(M.sum())
nx, ny = M.shape # nx=ny
x = np.array(list(mapping.keys()))
y = x # x and y have the same support
idx = list(mapping.values())
a = M.sum(axis=0)
b = M.sum(axis=1)
vara = (a[idx] * x ** 2).sum() - ((a[idx] * x).sum()) ** 2
varb = (b[idx] * y ** 2).sum() - ((b[idx] * y).sum()) ** 2
xy = np.outer(x, y)
ab = np.outer(a[idx], b[idx])
return (xy * (M - ab)).sum() / np.sqrt(vara * varb)
|
