I have my Arduino connected to one of my RPi's for data collection. The code is here for both the Pi and the Uno:
https://github.com/hdtodd/WeatherStation.
The key to making this work was the rs232 package by Teunis van Beelen,
http://www.teuniz.net/RS-232/, which provides RS232 service over the USB connection (look at the table at the bottom of this web page to see which ports are available on which systems).
My setup is:
- *Arduino connected (in this case to a Raspberry Pi-2B) via USB cable
*Power supply to RPi sufficient to power both Pi and Uno (2.5A in my case, I think)
*Pi connected to network via WiFi (Edimax dongle)
A Pi-2B or Pi-3B has sufficient performance to run the Arduino development environment reasonably well, in my opinion, and I do all my development on the Pi in this case. But I've also connected the Uno to my Mac and done development that way occasionally, too, just to make sure I can.
But in my case, I wanted the Pi to control the data collection process, store the data in a database, and display the results on a web page on demand, so it's usually more convenient to do the development and run the operation from the Pi.
Good luck! These are fun to work with!
David