how to draw networkX graph in flask?
Question
I am trying to to draw a graph with networkx and then show it in my flask webpage, but I dont know how to show it in my flask app? I used matplotlib but I am keep running to errors. I dont know how to do this part!
Any help would be appreciate it!
@app.route('/graph')
def graph_draw():
F = Figure()
G = nx.Graph()
G.add_node(1)
G.add_nodes_from([2, 3])
H = nx.path_graph(10)
G.add_nodes_from(H)
G.add_node(H)
G.add_edge(1, 2)
nx.draw(G)
p = plt.show()
return render_template('indexExtra.html',p=p)
1 answers
solution1
1 ACCPTED 2018-11-05 22:17:54
You can use flask's function send_file , which accepts either a filename or a file-like object, to create a route for the image and use another route to show the image inside a template.
You can save your graph plot like this:
nx.draw(G)
with open(filepath, 'wb') as img:
plt.savefig(img)
plt.clf()
As a more complete example here's something I did some time ago, a flask app that renders the n-th complete graph with at the route /<int:nodes> :
server.py
from flask import Flask, render_template, send_file
import matplotlib.pyplot as plt
from io import BytesIO
import networkx as nx
app = Flask(__name__)
@app.route('/<int:nodes>')
def ind(nodes):
return render_template("image.html", nodes=nodes)
@app.route('/graph/<int:nodes>')
def graph(nodes):
G = nx.complete_graph(nodes)
nx.draw(G)
img = BytesIO() # file-like object for the image
plt.savefig(img) # save the image to the stream
img.seek(0) # writing moved the cursor to the end of the file, reset
plt.clf() # clear pyplot
return send_file(img, mimetype='image/png')
if __name__ == '__main__':
app.run(debug=True)
templates/image.html
<html>
<head>
<title>Graph</title>
</head>
<body>
<h1>Graph</h1>
<img
src="{{ url_for('graph', nodes=nodes) }}"
alt="Complete Graph with {{ nodes }} nodes"
height="200"
/>
</body>
</html>
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