add chord diagrams

[guettli]

Thanks for your developing plotly.py!

There is a description how to create a chord diagram for version3:

https://plotly.com/python/v3/filled-chord-diagram/

It would be nice to have this for version4, too.

[guettli]

Just for the records, I found the holoviews Chord, which looks good: https://holoviews.org/reference/elements/bokeh/Chord.html

[kurt-rhee]

Also interested in Chord diagrams in v4

[mirk-00]

I also would like a Chord graph feature since other visualization packages already have it.

[matanox]

Should we understand it is no longer a working supported part of later versions of plotly?

[alexcjohnson]

That example will still work, but it's awfully cumbersome. We wouldn't be opposed to adding chord diagrams to plotly.js / .py, but there's already a Circos component in dash-bio that makes full-featured chord diagrams https://dash.plotly.com/dash-bio/circos

[matanox]

Thanks for the reference. Circos was probably the first to introduce chord diagrams for the masses, it is probably the most versatile today I would guess. What are your cons and pros for switching to use dash though?

[alexcjohnson]

Pros: you get access to a whole bunch more types of visualization that don't exist in plotly.js/.py (see also dash-cytoscape, dash-vtk, dash-leaflet... there's a ton out there) and you can hook them up to each other in ways that can make data exploration more efficient.

Cons: A bit of boilerplate because you need to create a Dash app to put the component into, and that app keeps an extra process running in order to serve interaction callbacks. If you want to run inside Jupyter see https://dash.plotly.com/dash-in-jupyter. FWIW We're exploring some ideas to simplify this, but no timeline as yet.