Plotly.js: Extend `categoryorder` to multicategory axes

[etpinard]

Currently we don't coerce categoryorder and friends for mulitcategory axes. Extending categoryarray and sorting will be a little challenging from an API standpoint.

• Should we refer to category pairs in categoryarray as 2-item arrays e.g. categoryarray: [['q1', 'A'], ['q2', 'B]]
• We'll have to disallow some combinations to ensure that we don't jump from one parent category to another and back
• We'll probably need to sort parent and child categories separately?

Related: https://github.com/plotly/plotly.js/issues/3723

Some context: https://community.plot.ly/t/ordering-on-multi-level-bar-charts/23747

[LarryMartell]

I have charts with 3 levels. I'd like for each level to be sorted within its higher level.

[davepattie]

controlling the child sort order within the parent would be great +1

[LarryMartell]

Any update on when this might be fixed?

[kmcentush]

I would love for this to be implemented as well.

[AndreasUntch]

Any updates on this feature? Hope it will get implemented soon

[nicolaskruchten]

This issue has been tagged with NEEDS SPON$OR

A community PR for this feature would certainly be welcome, but our experience is deeper features like this are difficult to complete without the Plotly maintainers leading the effort.

Sponsorship range: $10k-$15k

What Sponsorship includes:

• Completion of this feature to the Sponsor's satisfaction, in a manner coherent with the rest of the Plotly.js library and API
• Tests for this feature
• Long-term support (continued support of this feature in the latest version of Plotly.js)
• Documentation at plotly.com/javascript
• Possibility of integrating this feature with Plotly Graphing Libraries (Python, R, F#, Julia, MATLAB, etc)
• Possibility of integrating this feature with Dash
• Feature announcement on community.plotly.com with shout out to Sponsor (or can remain anonymous)
• Gratification of advancing the world's most downloaded, interactive scientific graphing libraries (>50M downloads across supported languages)

Please include the link to this issue when contacting us to discuss.

[nicolaskruchten]

See also https://github.com/plotly/plotly.js/issues/3723