However, instead of the parasite axes being overlaid with the primary one, I'd like it to be a separate subplot that I can put different data on. (Also, I'm trying to do this with a pair of y-axes, in case that's relevant. It's not immediately obvious how to adjust the example to do this with y instead of x.) Ultimately I want the second y-axis to set its range to some multiple of the first. So, for example, if I set one axis to have a y range of [0,64], I'd like the second subplot to automatically adjust its range to [0,32]. (I'd also like to be able to link the x axes to adjust together as normally done with the sharex keyword.)
but the result is a TypeError: unhashable type: 'Affine2D'.
Perhaps I'm getting transforms confused, and the transform keyword to add_subplot is used to define its location on the figure instead of how "twin" uses it to apparently scale the axes. The API just lists the keyword as expecting a type "Transform", and mentions that it's passed along to the Axes base class, which also just lists it as being of type "Transform".