I guess I'm not explaining myself clearly. Here's an example of the kind of thing I'm after (but not exactly the same):
The difference is that I want the color to be the number of data points in a particular bin (or the frequency of that bin), and the radial distance to be the speed. But I don't know how to stack the different-colored "sectors" (bins in radius and angle - the blue and green sectors) on top of each other, from the center, moving outward.
So again: in my plot I want the radius to be speed, with the data binned by speed, and the color to be proportional to the number of points in a speed bin at a particular angle range.