python - Show matplotlib plots (and other GUI) in Ubuntu (WSL1 & WSL2)

Question

So it seems on ubuntu for windows (windows subsystem for linux) people are suggesting we need to use Agg backend and just save images, not show plots.

import matplotlib
matplotlib.use('Agg') # no UI backend

import matplotlib.pyplot as plt
import numpy as np

t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2*np.pi*t)
plt.plot(t, s)
plt.title('About as simple as it gets, folks')

#plt.show()
plt.savefig("matplotlib.png")  #savefig, don't show

How could we get it to where plt.show() would actually show us an image? My current option is to override plot.show() to instead just savefig a plot-148123456.png under /mnt/c/Users/james/plots/ in windows and just have an explorer window open viewing the images.

I suppose I could host that folder and use a browser.

My goal is to be able to run simple examples like the code above without changing the code to ftp the images somewhere etc. I just want the plot to show up in a window.

Has anyone figured out a decent way to do it?

Answer 1

Ok, so I got it working as follows. I have Ubuntu on windows, with anaconda python 3.6 installed.

1. Download and install VcXsrv or Xming (X11 for Windows) from sourceforge(see edit below)
2. sudo apt-get update
3. sudo apt-get install python3.6-tk (you may have to install a different python*-tk depnding on the python version you're using)
4. pip install matplotlib (for matplotlib. but many other things now work too)
5. export DISPLAY=localhost:0.0 (add to ~/.bashrc to make permanent. see WSL2 below)

Anyways, after all that, this code running in ubuntu on wsl worked as is:

import matplotlib.pyplot as plt
import numpy as np

t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2*np.pi*t)
plt.plot(t, s)

plt.title('About as simple as it gets, folks')
plt.show()

result:

Maybe this is better done through a Jupyter notebook or something, but it's nice to have basic command-line python matplotlib functionality in Ubuntu for Windows on Subsystem for Linux, and this makes many other gui apps work too.

For example you can install xeyes, and it will say to install x11-apps and installing that will install GTK which a lot of GUI apps use. But the point is once you have your DISPLAY set correctly, and your x server on windows, then most things that would work on a native ubuntu will work for the WSL.

Edit 2019-09-04 : Today I was having issues with 'unable to get screen resources' after upgrading some libraries. So I installed VcXsrv and used that instead of Xming. Just install from https://sourceforge.net/projects/vcxsrv/ and run xlaunch.exe, select multiple windows, next next next ok. Then everything worked.

Edit for WSL 2 users 2020-06-23 WSL2 (currently insider fast ring) has GPU/docker support so worth upgrade. However it runs in vm. For WSL 2, follow same steps 1-4 then:

5. the ip is not localhost. it's in resolv.conf so run this instead (and include in ~/.bashrc):

 export DISPLAY=`grep -oP "(?<=nameserver ).+" /etc/resolv.conf`:0.0

6. Now double-check firewall: Windows Security -> Firewall & network protection -> Allow an app through firewall -> make sure VcXsrv has both public and private checked. (When Launching xlaunch first time, you might get a prompt to allow through firewall. This works too. Also, if VcXsrv is not in list of apps, you can manually add it, eg from 'C:program filesvcxsrvvcxsrv.exe')
7. Launch VcXsrv with "Disable access control" ticked

Note: a few WSL2 users got error like couldn't connect to display "172.x.x.x:0". If that's you try to check the IP address stored in DISPLAY with this command: echo $DISPLAY. If the showed IP seems to be wrong (i.e. "8.8.8.8" or another not working IP address) you need to change the code in ~/.bashrc showed in the point 5 to something that will get your instance's ip address. One user said this worked: export DISPLAY=$(ifconfig | grep inet | awk '{print $2}' | head -n 1 | awk '{print $0":0"}'). However for some others it did not work. YMMV, but just find your IP and use if for DISPLAY. For most WSL2 users, the command in #5 works.