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#-*- coding: utf-8 -*-
"""Generators of x-y pairs of node data."""
import networkx as nx
from networkx.utils import dict_to_numpy_array
__author__ = ' '.join(['Aric Hagberg <aric.hagberg@gmail.com>'])
__all__ = ['node_attribute_xy',
'node_degree_xy']
def node_attribute_xy(G, attribute, nodes=None):
"""Return iterator of node-attribute pairs for all edges in G.
Parameters
----------
G: NetworkX graph
attribute: key
The node attribute key.
nodes: list or iterable (optional)
Use only edges that are adjacency to specified nodes.
The default is all nodes.
Returns
-------
(x,y): 2-tuple
Generates 2-tuple of (attribute,attribute) values.
Examples
--------
>>> G = nx.DiGraph()
>>> G.add_node(1,color='red')
>>> G.add_node(2,color='blue')
>>> G.add_edge(1,2)
>>> list(nx.node_attribute_xy(G,'color'))
[('red', 'blue')]
Notes
-----
For undirected graphs each edge is produced twice, once for each edge
representation (u,v) and (v,u), with the exception of self-loop edges
which only appear once.
"""
if nodes is None:
nodes = set(G)
else:
nodes = set(nodes)
node = G.node
for u,nbrsdict in G.adjacency_iter():
if u not in nodes:
continue
uattr = node[u].get(attribute,None)
if G.is_multigraph():
for v,keys in nbrsdict.items():
vattr = node[v].get(attribute,None)
for k,d in keys.items():
yield (uattr,vattr)
else:
for v,eattr in nbrsdict.items():
vattr = node[v].get(attribute,None)
yield (uattr,vattr)
def node_degree_xy(G, x='out', y='in', weight=None, nodes=None):
"""Generate node degree-degree pairs for edges in G.
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)
Use only edges that are adjacency to specified nodes.
The default is all nodes.
Returns
-------
(x,y): 2-tuple
Generates 2-tuple of (degree,degree) values.
Examples
--------
>>> G = nx.DiGraph()
>>> G.add_edge(1,2)
>>> list(nx.node_degree_xy(G,x='out',y='in'))
[(1, 1)]
>>> list(nx.node_degree_xy(G,x='in',y='out'))
[(0, 0)]
Notes
-----
For undirected graphs each edge is produced twice, once for each edge
representation (u,v) and (v,u), with the exception of self-loop edges
which only appear once.
"""
if nodes is None:
nodes = set(G)
else:
nodes = set(nodes)
xdeg = G.degree_iter
ydeg = G.degree_iter
if G.is_directed():
direction = {'out':G.out_degree_iter,
'in':G.in_degree_iter}
xdeg = direction[x]
ydeg = direction[y]
for u,degu in xdeg(nodes, weight=weight):
neighbors = (nbr for _,nbr in G.edges_iter(u) if nbr in nodes)
for v,degv in ydeg(neighbors, weight=weight):
yield degu,degv
# fixture for nose tests
def setup_module(module):
from nose import SkipTest
try:
import numpy
except:
raise SkipTest("NumPy not available")
try:
import scipy
except:
raise SkipTest("SciPy not available")
|
