I have a 5-node directed network that I want to represent graphically using networkx. The nodes should be connected in this way:
- Every node is connected to each other with a dashed line
- Active connections are read from a file and are represented by solid black arrows
- Active connections to and from the node where the code is running (in this case, node 1) should be in red.
The code does what I want, but for some reason, even though I specify arrow=True when I want to make the red edges, the arrow head does not show up. It seems to be ignoring every option I specify after edge_color, for some reason.
I noticed that when I draw the edges between all nodes, if I do not specify arrows=False it ignores the style='dashed', alpha=0.5 and just draws a gray solid line. Does that have anything to do with the issue?
Here is my code, with the problematic parts annotated with comments:
import networkx as nx
import matplotlib.pyplot as plt
class Graph(nx.DiGraph):
def __init__(self, *args, **kwargs):
self.nodeNum = 1
self.pos = {'1': (0, 10),
'2': (10, 3),
'3': (6, -8),
'4': (-6, -8),
'5': (-10, 3)}
self.allConns = []
for i in range(5):
for j in range(i, 5):
self.allConns.append((str(i+1), str(j+1)))
super().__init__(*args, **kwargs)
def read_connections(self):
filename = 'PATH/TO/FILE'
with open(filename) as f:
self.connList = []
self.nodeConns = []
for line in f:
if line[-2] == '1':
self.connList.append((str(line[0]), str(line[1])))
if line[0] == self.nodeNum or line[1] == self.nodeNum:
self.nodeConns.append((str(line[0]), str(line[1])))
else:
pass
else:
pass
def generate_graph(self):
self.read_connections()
self.add_nodes_from(self.pos.keys())
self.add_edges_from(self.connList)
def draw_graph(self, fig=None, ax=None, show=False):
if fig == None:
fig = plt.figure()
if ax == None:
ax = fig.add_subplot(111)
ax.axis('off')
options = {'node_color': 'cyan',
'node_size': 1500,
'width': 2,
'arrowstyle': '-|>',
'arrowsize': 14,
'font_size': 20
}
# This works, but if I do not specify arrows=False it draws solid lines with no transparency
nx.draw_networkx_edges(self, self.pos, ax=ax, edgelist=self.allConns, edge_color='grey',
style='dashed', alpha=0.5, arrows=False)
# This is the main part which works. It connects the nodes from the file with black arrows
nx.draw_networkx(self, self.pos, arrows=True, ax=ax, **options)
# This is the part that gives me problems. It seems to ignore every option after edge_color
nx.draw_networkx_edges(self, self.pos, ax=ax, edgelist=self.nodeConns, edge_color='r',
style='solid',alpha=1,
arrows=True, width=3, arrowsize=14, arrowstyle='-|>')
nx.draw_networkx_nodes(self, self.pos, ax=ax, nodelist=[self.nodeNum], node_color='r',
node_size=1500)
fig.tight_layout()
if show == True:
fig.show()
if __name__ == '__main__':
graph = Graph()
graph.generate_graph()
graph.draw_graph(show=True)
And an example of the result. Note how the red edges do not have arrow heads.
