[Pie][Lens] Allow the labels to be displayed only outside the chart

[stratoula]

Describe the feature:
Currently both Lens and the agg-based pie allow the users to display the labels either inside the bar or inside/outside.
The second one automatically positions the labels outside if they don't fit inside the slice.
We would like to give a third option to only display the labels outside. Elastic-charts offers this https://elastic.github.io/elastic-charts/?path=/story/sunburst--linked-labels-only&globals=theme:light

[elasticmachine]

Pinging @elastic/kibana-vis-editors (Team:VisEditors)

[monfera]

Just to clarify, the labels with leader lines are an option intended for single layer pie charts, and not for multi-layer sunburst diagrams

[stratoula]

This is already available in the agg-based pie by switching on the Show top level only switch

[monfera]

Maybe it can be fixed as a bug

[ghudgins]

Using labels around a pie is not recommended for a few reasons:

• Readability is the primary one - the text is exactly where the vis is and the vis is as large as the display will alllow.
• While it may look good on a larger display you cannot guarantee that a user is viewing on a large window where there is enough space for both the labels and the slices. The labels, when long, can take up a lot of the space
• labels outside of sunburst leave either a confusing label for the middle of the sunburst or no label--both are not optimal for the visualization's comprehension

We were opinionated when we didn't include this option in the implementation via elastic-charts and would like to keep this option out of Kibana for these reasons at this time...

However, as long as we support donuts it does make sense to have this option for that vis type--especially if we ever include additional donut controls around the "hole" size. Also there may be preferences by our users that they can express on this issue!!

As an aside, a treemap can be a much better display of proportion-to-whole data like this over both donut and pie. we do have plans to add #104223 and #107059 as well as alternatives to pie in the future too.

[ghudgins]

+1 on https://discuss.elastic.co/t/label-leader-lines-on-pie-charts/286365

[stratoula]

I wonder if we want to implement this enhancement as it seems is not a good practice. Maybe we should close this, wdyt @markov00 ?

[markov00]

This has various implications and complexity on how to handle outer labels.
Rendering labels correctly is always problematic, there isn't a clear solution that works for all cases. Showing each label outside the pie means:

• consider that there could be a considered reduction of the pie size to accommodate the outside labels
• the reduced size is relative to the number of labels and the position of each slice. If we have small slices near the top/bottom we need more space to vertically (shrinking the pie) to accommodate the label and their link segments.

This requires a good investment in time and effort to handle, I think we should probably spend that time on handling labeling on chart alternatives (like single stacked bar chart) that simplify the label positioning, and reduce the screen-space waste

[stratoula]

Thank you for contributing to this issue, however, we are closing this issue due to inactivity as part of a backlog grooming effort. If you believe this feature/bug should still be considered, please reopen with a comment.