Medium has a piece by Adam J. Calhoun which is surprisingly interesting: though I’m still puzzling over what it is that might be interesting about the isolated study of the punctuation of a book. He says he was started on this track by a series of posters from Between the Words — which are indeed quite impressive. I’m not sure what lessons we can draw from comparing the punctuation in Wuthering Heights with that in Pride and Prejudice, but they do make for a nice posters. Nineteenth century fiction seems to go in for punctuation, they have tightly wound spirals, though of course one really needs to correct for page count before drawing any conclusions.
Mr Calhoun has written a script so you can do this yourself, possessed as you of course are of a digital file before you start. A link can be found at his blog. His heat map conversions, shown at the end of his blog post, seem almost to be the visual equivalent of conceptual poetry.