TSVB Legend Ordering does not seem to work as expected

[willemdh]

Kibana version: 7.3.2

Elasticsearch version: 7.3.2

Server OS version: CentOS 7.6

Browser version: Chrome

Browser OS version: Windows 10

Original install method (e.g. download page, yum, from source, etc.): yum

Describe the bug: For some reason when I create 7.3.2 tsvb timeseries chart and select order by "Max of system.diksio.read.bytes", the legend is not sorted at all:

Steps to reproduce:

1. Creatae tsvb visualisation. This is the json of the visualisation I'm using:
   {"attributes":{"description":"","kibanaSavedObjectMeta":{"searchSourceJSON":"{\"query\":{\"query\":\"\",\"language\":\"kuery\"},\"filter\":[]}"},"title":"Elastic Beats Metricbeat System DiskIO Read Bytes Windows Disk Name Time Series","uiStateJSON":"{}","version":1,"visState":"{\"title\":\"Elastic Beats Metricbeat System DiskIO Read Bytes Windows Disk Name Time Series\",\"type\":\"metrics\",\"params\":{\"id\":\"61ca57f0-469d-11e7-af02-69e470af7417\",\"type\":\"timeseries\",\"series\":[{\"id\":\"61ca57f1-469d-11e7-af02-69e470af7417\",\"color\":\"#68BC00\",\"split_mode\":\"terms\",\"metrics\":[{\"id\":\"61ca57f2-469d-11e7-af02-69e470af7417\",\"type\":\"max\",\"field\":\"system.diskio.read.bytes\"},{\"unit\":\"\",\"id\":\"b4c50a50-dec0-11e9-8645-256c9a1c014d\",\"type\":\"derivative\",\"field\":\"61ca57f2-469d-11e7-af02-69e470af7417\"},{\"unit\":\"\",\"id\":\"ee8a5100-dec0-11e9-8645-256c9a1c014d\",\"type\":\"positive_only\",\"field\":\"b4c50a50-dec0-11e9-8645-256c9a1c014d\"}],\"separate_axis\":0,\"axis_position\":\"right\",\"formatter\":\"bytes\",\"chart_type\":\"line\",\"line_width\":1,\"point_size\":1,\"fill\":\"0.2\",\"stacked\":\"none\",\"label\":\"\",\"terms_field\":\"system.diskio.name\",\"terms_order_by\":\"61ca57f2-469d-11e7-af02-69e470af7417\",\"terms_size\":\"10\",\"terms_direction\":\"desc\"}],\"time_field\":\"@timestamp\",\"index_pattern\":\"metricbeat\",\"interval\":\"auto\",\"axis_position\":\"left\",\"axis_formatter\":\"number\",\"axis_scale\":\"normal\",\"show_legend\":1,\"show_grid\":1,\"default_index_pattern\":\"metricbeat\",\"default_timefield\":\"@timestamp\",\"filter\":{\"query\":\"event.dataset : \\\"system.diskio\\\" AND host.os.family : \\\"windows\\\"\",\"language\":\"kuery\"}},\"aggs\":[]}"},"id":"d1982970-dec3-11e9-8536-f91cecc85017","migrationVersion":{"visualization":"7.3.1"},"references":[],"type":"visualization","updated_at":"2019-09-24T12:07:02.791Z","version":"WzU1MDUsMV0="}
2. The above visualisation is ordered desc by system.diskio.name
3. Ordering does not make sense

Expected behavior: TSVB legend order works fine, even for derivatives

Screenshots (if relevant):

Any additional context: https://discuss.elastic.co/t/tsvb-descending-order-not-working-as-expected/200862

[elasticmachine]

Pinging @elastic/kibana-app

[willemdh]

Anyone ever had a look at this? It should not be so hard to make the TSVB legend order decently?

[willemdh]

@timroes Yes, this is still valid in 7.8.1... For example:

Config:

Legend should be sorted?

[sulemanof]

@markov00 @nickofthyme

It seems the user wants the chart to sort the legend items by values (not a series label - default).
That means, the legend should reorder its items on chart mouseover event depending on x-axis position.
I assume elastic-charts doesn't have such an option, and it only has a possibility to order items by the specified series sort index.

Does the elastic/elastic-charts#795 cover the issue?

[nickofthyme]

@sulemanof So for example at a given x point the series in the legend/tooltip would sort by the series values at that point via min, max, etc.?

If so, you are correct that is not available in current elastic charts.

I don't think elastic/elastic-charts#795 mentions exposing the value of the series but that should be an easy addition. I added a comment to reflect this ability.

[sulemanof]

@sulemanof So for example at a given x point the series in the legend/tooltip would sort by the series values at that point via min, max, etc.?

You're completely right !
Thanks @nickofthyme , would be a great addition since I've seen couple of the same request already 👍

[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.