Step 1. Figure out for each region which vectors are inside of it.
Step 2. Remove all other vectors (per region).
Step 3. Compute the average of the remainder.
I didn’t have your lunchbox component, so I just created three circles instead. Nice is that you can manually drag them around so you can see the way it affects the average.
191112_GH_Vectorlines.gh (69.5 KB)
Pro-tip, you can just multiply numbers and vectors directly, no need to measure the length, multiply the length, then assign the new length.
Also note I scaled the display of the average vectors by a factor of 3 to make them more visible, remove that expression from the Vector Display input if you don’t want that.