Using python and matplotlib on android

Is it easy, no.

Can it be done? Yes. I believe a skilled Python / Android developer could do it in 2 to 8 hours of effort.. It's a rare and complex request.

Why do I think it can be done? This sample: http://matplotlib.org/examples/pylab_examples/webapp_demo.html

Using a different library, and not abstracted for data without live hardware, this sample shows me that SL4A can do web-based graphics:http://www.smartphonedaq.com/android-python-ecg.page

Now, if you were talking native GUI graphics in Android - then I'm focused way too much on the web methods of publishing with SL4A ;)

Pydroid is great for Matplotlib on Android, supports Numpy and many other libraries:

Pydroid for Python 2.7

Pydroid 3 for Python 3.6

There is an app called Gnuroot that allows you to run a kind-of chroot (proot), where you can install a linux distro such as debian, archlinux...
For the gui, there is the option to run a vncserver for an X server and use some android vnc client app to show the screen.

I use the non-gui version of gnuroot and it works well. I now have a command line debian wheezy on android lollipop arm. One minor thing i miss, is armhf (hardware floating point which my nexus7's processor can do) support instead of armel (software floating point).