I could see a stackR transform which takes an r (radius) channel in and produces r1 and r2 output channels, which you would use in conjunction with an annulus type mark. Maybe the dot mark should allow r1 and r2 input channels and have similar behavior to barY’s y, y1, and y2 channels. The sqrt transform should ensure that the rings have area proportional to value.
I could see a stackR transform which takes an r (radius) channel in and produces r1 and r2 output channels, which you would use in conjunction with an annulus type mark. Maybe the dot mark should allow r1 and r2 input channels and have similar behavior to barY’s y, y1, and y2 channels. The sqrt transform should ensure that the rings have area proportional to value.