Plotting graph without blocking execution in python

Question

I want to plot graph inside a while loop, but execution is blocked after plt.show(G) command and resumes when i manually kill the plot window.

Code:

while True:    
        print G.edges()
        Q = #coming from a function
        if Q > BestQ:
            nx.draw(G)
            plt.show(G)
        if G.number_of_edges() == 0:
            break

This is the output of G.edges() for two iterations:

[(0, 1), (1, 2), (1, 4), (1, 9), (2, 6), (3, 5), (5, 7), (5, 8), (5, 10)]
[(0, 1), (1, 4), (1, 9), (2, 6), (3, 5), (5, 7), (5, 8), (5, 10)]

How to make this continue after plotting???

try calling plt.ion() before the while loop.

Dominik Neise
– Dominik Neise

2014-10-12 08:15:49 +00:00
Commented Oct 12, 2014 at 8:15 — Dominik Neise
– Dominik Neise, Commented Oct 12, 2014 at 8:15
try plt.draw(), plt.show() may not be the best option

Srivatsan
– Srivatsan

2014-10-12 08:25:03 +00:00
Commented Oct 12, 2014 at 8:25 — Srivatsan
– Srivatsan, Commented Oct 12, 2014 at 8:25
plt.ion() not working.

suri
– suri

2014-10-12 09:02:22 +00:00
Commented Oct 12, 2014 at 9:02 — suri
– suri, Commented Oct 12, 2014 at 9:02

joaquin · Accepted Answer · 2014-10-12 11:05:06Z

1

You have to use interactive on and plt.draw.
Here you have a working example.
As I do not have your algorithm to generate your G graphs, I will draw constinuously the same network. Anyway, as each call to nx.draw(G) creates a different graph, you can see it updating the plot at each call.

import matplotlib.pyplot as plt
import time
import networkx as nx

plt.ion()   # call interactive on

data = [(0, 1), (1, 2), (1, 4), (1, 9), (2, 6), (3, 5), (5, 7), (5, 8), (5, 10)]

# I create a networkX graph G
G = nx.Graph()
for item, (a, b) in enumerate(data):
    G.add_node(item)
    G.add_edge(a,b)

# make initial plot and set axes limits.
# (alternatively you may want to set this dynamically)
plot, = plt.plot([], [])
plt.xlim(-1, 3)
plt.ylim(-1, 3)

# here is the plotting stage.
for _ in range(10):           # plot 10 times
    plt.cla()                 # clear the previous plot
    nx.draw(G)
    plt.draw()
    time.sleep(2)             # otherwise it runs to fast to see

answered Oct 12, 2014 at 11:05

joaquin

86k31 gold badges146 silver badges155 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

suri Over a year ago

plt.draw() is not showing any figure. Any idea why??

joaquin Over a year ago

Do you refer to my code ?. The code posted is working perfect with python 2.7 in windows 7. It shows the figure and refresh it 10 times. Did you copied it exactly as it is and got nothing draw? Did you get any error ? If you refer to your own code you should post the minimal executable example that doesnt work in your case.

suri Over a year ago

I am on linux and using Spyder IDE. It didn't give any error. It just didn't draw anything.

joaquin Over a year ago

try it on command line, out from Spyder. I have no linux box here but I will try it in ubuntu this afternoon

Collectives™ on Stack Overflow

Plotting graph without blocking execution in python

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related