fix(grapher): don't offer non-plottable entities for selection

[sophiamersmann]

• fixes Some charts allow selecting entities for which there is no data #1341

Problem

• Fixes a bug where entities were offered for selection that couldn't be plotted
• This happened for:
  • StackedArea and StackedBar charts (default settings)
  • LineCharts if the config's missingDataStrategy was set to hide

Technical details

• The chart interface is extended by an additional (but optional) chart table transform, transformTableForSelection
  • If given, transformTableForSelection is responsible to exclude all entities that are not plottable
• grapher.tableForSelectioncalls transformTableForSelection of the current chart instance (if defined)
• transformTableForSelection has been implemented for a subset of chart types whose entity selector was sometimes buggy (see above)
  • it runs basic clean up transforms, interpolation, and the filter transforms that implement the specified missing data strategy (only if necessary)

[marcelgerber]

Nice work, overall I think this makes sense.

However, I'm thinking that the whole tableForSelection concept is hindering us a bit, and it would be a bit more straightforward to just make availableEntities an (optional) chart instance getter.

That way, any charts could run some code to tell grapher which entities they have available (potentially by running table transforms), and otherwise, they just default to this.inputTable.availableEntities.
Overall, just getting rid of the tableForSelection indirection in between. An OwidTable is not the best format to communicate available entities, I think...

[sophiamersmann]

mhh.. I mean for now we're only grabbing the available entities, but I imagine that Christian builds the new entity selector on top of a table – so we might be a little more flexible in the future if chart instances were allowed to customise that table (cc @samizdatco)

[marcelgerber]

mhh.. I mean for now we're only grabbing the available entities, but I imagine that Christian builds the new entity selector on top of a table – so we might be a little more flexible in the future if chart instances were allowed to customise that table

Ah, you're right about that of course. Good thinking!

[github-actions]

This PR has had no activity within the last two weeks. It is considered stale and will be closed in 3 days if no further activity is detected.

[samizdatco]

mhh.. I mean for now we're only grabbing the available entities, but I imagine that Christian builds the new entity selector on top of a table – so we might be a little more flexible in the future if chart instances were allowed to customise that table (cc @samizdatco)

I didn't change much in terms of how the entity-selector populates its list of items: they're still coming from the grapher object's selection attribute (and in particular that SelectionArray's availableEntities list):

owid-grapher/packages/@ourworldindata/grapher/src/modal/EntitySelectorModal.tsx

Lines 111 to 118 in dbe6f21

	@computed private get searchableEntities(): SearchableEntity[] {
	const { selectedEntityNames } = this.selectionArray
	return this.sortedAvailableEntities
	.filter((name) => !selectedEntityNames.includes(name))
	.map((name) => {
	return { name } as SearchableEntity
	})
	}

The rest of my changes can be found in https://github.com/owid/owid-grapher/commits/entity-selector-redesign