https://github.com/observablehq/plot/blob/main/test/plots/ca...
It’s not a perfect fit for Plot because Plot wants at most one instance of each scale in a plot. (I.e., Plot isn’t designed to support dual-axis charts where you have two y scales. Dual-axis charts tend not to be a good idea anyway.) So to implement parcoords we use a normalize transform to map values to [0, 1] and then render axes manually. We might revisit this topic in the future as Plot grows. I agree that parcoords are very useful for initial exploration, especially with interactive filtering.
It would also be reasonable to have a more specialized component for parcoords — not everything has to live in Plot. For example we found ourselves making a lot of dashboards of time-series data, so we built this reusable component on top of D3 instead of Plot: