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Comment by mbostock | Hacker News Reader

We’ve been developing Observable Plot for a while now, and I’m thrilled to finally have it out in the public. Feel free to ask me any questions! Or share your plots on Observable and I can make suggestions. ;)

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I went through the tutorials/demos and this seems very intuitive. I don't do a lot of visualisation, but when I do, I've found manually coaxing data and configuring visual parameters to please a library to be tedious as it's time spent doing busy work I'd rather spend analysing the results. So for me the major drawcard is being able to drop a simple table of results in and let the library handle the necessary inferences for the type of vis I'm after. If it works for the majority of my use-cases, that's a big timesaver for me.

One type of visualisation I sometimes (honestly rarely) use but is extremely useful for finding unintuitive relationships in higher dimensions of data are parallel coordinates charts (actually it's your d3 code I've been borrowing in the past - so thanks for that!) Is this something that can be achieved with Plot at this stage? I'm not sure if it would be a facet, a transform, or something else, like a cross between marks and links (if that's doable).

Anyway, definitely bookmarked - I'll be sure to spend more time using this next time I need to visualise some data, looks like it will handle a lot of the standard vis without the typical boilerplate, thanks for releasing this.

Thanks for the feedback. There’s a test in the repo that does parallel coordinates:

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:

https://observablehq.com/@observablehq/timechart

Thanks for the reply - even if it's not within the design scope your test code reads much cleaner than the code I've used in the past (where perhaps naively I've manually transformed and presented each dimension individually where you've done a single normalise operation). For sure every tool fits a particular paradigm and parcoords are incredibly niche, but plotting aside from the demo code you provided I can see some general purpose uses for the transformations as well and definitely a good addition to the tool-belt. Good stuff!

I didn't see any mention of this, but does Observable Plot support interactive charts? E.g. detailed summary on data point hover?

Yes, in a variety of ways. All marks currently support native tooltips (the title channel), and in the near future we’ll be releasing more interactions that you can compose into the chart, e.g. for brushing or pointing. As I mentioned in another comment here, Plot is designed to leverage Observable’s language-level interactivity (dataflow) — so all plots are reactive by default, and plots can expose an interactive selection to the rest of the notebook.

I'd love to use something like Plot or Vega but this is exactly why I am still using D3. Zoom, Delaunay tooltips, and extensible interactivity that I can get to work well in a React based application are very important. Unfortunately Vega's solution to anything interactive seemed incredibly awkward to me at the time.

The only time it seemed like Vega made sense was publication style graphics which was unfortunate.

This can help build interactivity: https://vimeo.com/453645616 http://vega.github.io/lyra/

I've been using D3 for charts for a while. I'm not a power-user by any means, but I understand it enough to make basic plots.

When would I use this instead of straight D3?

Most of the time. Unless you want or need a bespoke visualization, Plot will let you construct a meaningful plot with much less time and effort. (That said, Plot is brand new and still under development, so it might not yet have the specific features you need.)

When you only care about which visual encodings best represent your data, and not how those encodings are implemented in SVG/CSS.

Hey Mike, thanks for all the work you've been doing - I first used D3 back in 2013/2014 and been using them for side projects since.

I haven't dug into the whole v3/v4 modularisation, so that might answer it, but is there a way to minimise the dependencies that Plot brings? You say it needs D3, but what of it does it need specifically, the whole thing? It's just that it's 250K or so, so I was wondering what the minimal setup here is.

Cheers and congrats on the release!

Always a joy to read your code and loved the 'In the spirit of show don’t tell' notebook. Quickly grasped what it's about.

Edit: deleted my question, as it is answered here https://observablehq.com/@observablehq/plot-vega-lite

It looks awesome, but from the forums it doesn't appear that there is a built-in way to output direct to a pdf. I would value that feature, as options to convert html to pdf often have page boundary and formatting difficulties.

Am I missing anything, and is there a chance this feature might be added in the near term?

Plot generates SVG. There’s a variety of tools you can use to convert SVG to PDF. Plot is intended to be used on the web so I don’t think we’ll add direct to PDF rendering. (Though it’s possible that Observable might support it — Observable already supports download options that render SVG to PNG for example.)

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