Thanks for the feedback! Note that in Plot, the datum attached to svg element defaults to the *index* of that datum in the data array. This is because we're working with channels, which are materialized arrays of values (see Plot.valueof).

Thanks for the response! I presented this notebook to the data science group at DCEG and they were impressed with Observable Plot. Given how much is there already in V1 I'm very excited for updates! I see there is a plan to add classes to the the different components, this will be really useful for D3 selections. But is there a plan to store some of the stuff used to generate the plots (e.g. scales) on the Plot object? This would make it easier to augment the plots with D3 (in this example, I had to recalculate the scales from the bounding box). Or is there a better way of doing this that I am missing?

Classes are discussed here: https://github.com/observablehq/plot/issues/381 (with a PR). Scales are accessible with a sort of a hack, it's definitely something we're considering; I'm not sure what types of interactions you're trying to achieve, but maybe this experimental tooltip plugin could give you ideas? https://observablehq.com/@fil/experimental-plot-tooltip-01 ; let me know if you have a specific use case in mind