Train a classifier on MNIST, then draw numbers and see the output of the classifier updated live as you draw.

demo

I'm using running on a free dyno from Heroku for the demo backend, so it might take a minute or two to wake up when you first open the page.

Digit recognition is done with a Convolutional Neural Network implemented with Keras and Tensorflow.

There are two different ways you can run this thing:

1. a pure python program implementation that uses matplotlib for the UI
2. a web app that uses Elm for the frontend and a Python websocket server for the backend

They have essentially equivalent functionality; the web version was written purely because I like having a demo I can link to.

• Python 3.6
• Python libraries:
  • matplotlib, scikit-image, numpy, keras, tensorflow
  • websockets (only required if you want to run the websocket server)
• Elm 0.18

After using conda or pip to install: matplotlib, scikit-image, numpy, and keras:

$ cd backend
$ python train_model.py

After training finishes (which can take a while):

$ python matplotlib_frontend.py

Draw on the plot that comes up by dragging with your mouse, and press any key to erase.

First you'll have to run a server:

cd backend
python train_model.py
python server.py --address localhost --port 8765

Then, build and run the Elm app:

$ cd ../frontend
$ elm-package install
$ elm-make src/App.elm --output=app.html

Open frontend/app.html in a web browser. If you draw on the page that comes up, you should see the question mark in the bottom left of the page turn into a number. If it doesn't, something went wrong on the python side.

The server address is hardcoded in frontend/src/App.elm code due to <insert weak excuses>, so if you want to point this at a remote server you'll need to update that manually.

It should work in any modern desktop browser, but I've only tried this in Google Chrome and Microsoft Edge. It works fine in both, but Edge makes adjacent polygons in SVGs look prettier.

The Elm app does not respond to touch events, so, even though it'll run in mobile browsers, you won't be able to interact with it at all.