The layer's series, each with its position among the subplot's traces
The polar subplot they are drawn on (polar, polar2, …)
Whether these are barpolar traces rather than scatterpolar
One selector per series, or undefined when none can be built or the subplot cannot be named safely
Polar selectors: one per series, which is what a line-shaped layer needs.
LineTracepairs its series with its selectors by position, so a single selector covering the whole layer would resolve to nothing on a chart with more than one series. Plotly gives every scatter group atrace{uid}compound class, so each series can be named directly; barpolar's groups carry no uid and are counted within the subplot'sg.barlayerinstead.A uid that is not a usable class name — plotly generates safe ones, but an author may set
uidto anything — withdraws the whole list rather than emitting a selector that would silently match nothing.