Admin
1
I am quite new for networkx and I am asking help from the Stackeroverflow community.
I am trying to combine nodes and edges that have a common starting node as shown below in the figure. The arrow shows the expected result.
nodes_to_combine = [n for n in graph.nodes if len(list(graph.neighbors(n))) == 2]
for node in nodes_to_combine:
graph.add_edge(*graph.neighbors(node))
nx.draw(graph, with_labels=True)
Can anyone help me to figure out this?
NetworkX has no functions to merge nodes in the graph so it should be implemented manually. Here is the example without attributes merging (it can has its own logic):
def merge(G, n1, n2):
# Get all predecessors and successors of two nodes
pre = set(G.predecessors(n1)) | set(G.predecessors(n2))
suc = set(G.successors(n1)) | set(G.successors(n2))
# Create the new node with combined name
name = str(n1) + '/' + str(n2)
# Add predecessors and successors edges
# We have DiGraph so there should be one edge per nodes pair
G.add_edges_from([(p, name) for p in pre])
G.add_edges_from([(name, s) for s in suc])
# Remove old nodes
G.remove_nodes_from([n1, n2])
Here is how it works:
import networkx as nx
G = nx.DiGraph()
G.add_edges_from([
('0','20'),
('10','20'),
('10','30'),
('20','40'),
('30','50'),
])
nx.draw(
G,
pos=nx.nx_agraph.graphviz_layout(G, prog='dot'),
node_color='#FF0000',
with_labels=True
)
merge(G, '20', '30')
nx.draw(
G,
pos=nx.nx_agraph.graphviz_layout(G, prog='dot'),
node_color='#FF0000',
with_labels=True
)
