Pie charts have a lot of inherent issues. In many cases a bar chart is a much better choice, though pie charts can be useful if certain conditions are met.

For more insight into why pie charts are often a poor visualization choice, read Steve Wexler's recent book, The Big Picture.

I ran into this exact quandry when my home thermostat died late last year. Didn't want Nest/Google nor anyone else getting my data. Furthermore, I'm rural so broadband is expensive and sometimes flakey, so that was another reason to want a local-net-only solution, but there were no good ones I could find.

So I just built my own smart thermostat based on a Raspberry Pi: https://github.com/chaeron/thermostat

Since then, I've added battery-powered remote sensors (temp, humidity, pressure, water detection, etc.) to monitor key areas in and outside of the house. These were based on Arduinos (to keep power usage low) and the open source MySensors framework (https://www.mysensors.org/)

Fun project, works great, no security issues or cloud crap. ;-)

More recently I've built on that experience and am working on a dirt bike telemetry project which is based on an Arduino Mega with a GPS module, 9-axis motion sensor, hall effect sensors (for wheel spin/RPM detection) and more. The device captures real time info about the location and movement of the bike (eg. pitch, lean angle, etc.) and then can be used to overlay gauges and a moving 3D bike model over top of headcam footage captured during a ride.

No wifi...no support outside the USA....onerous DRM.

What a waste of time from Amazon. They could have pwned the ebook market just by fixing the above three things.

Very disappointing for a company of Amazon's stature.

Oh well....nothing to read here. (all puns intended)

In the winter time (and where I am, it's damned cold out during the winter...snow banks are over my head right now), I have to shut off the heat vent in my office.

The heat thrown my all the machines in here, one main dev box, 1 laptop and 3 small appliance servers, plus all the peripherals keep the office nicely heated all winter.

So...what waste heat...I use mine, thanks!