> This is almost what I had before. The key argument against it was that np.abs
> (data) creates a float array which is 8 times larger than a bool/byte array of
> the same size.

Yes. I figured that in the mean time, and decided it was a bad idea.
Sorry for the noise. I am slow. Maybe it's worth putting a comment on
this design decision, to avoid reiterating this discussion.

G