Generating imaginary maps on an e-paper display

I bought a small e-paper display "hat" for a Raspberry Pi early this year. The whole ensemble is small enough to put next to a mouse pad or stick to a monitor, and while I've not found a practical use for it, it's been really fun to find impractical uses for it. Earlier this year I was using it to display Amiga demos at 0.0003 frames per second, and last night I made an imaginary map generator.

The idea behind map generation is: you generate a random height map, and then decide the water is at. Anything above that height is land. There are lots of different ways to generate the height map; this page gives an interesting overview.

Code is here. Running randomisland.py on a Pi will display one random island per hour, assuming you have the same (inkyphat) display as I do. Alternatively, you can run randomisland3.py on anything and it will output a random map using block-drawing characters on the terminal. Fun things to play with if you're taking this latter option include the choice of nonlinearity (see nonlinear_3col and friends) and the palette (replace INKY with GREYS or FULLCOLOUR).