Contour selectors: the curves plotly drew for one level at a time.
Plotly gives every level a g.contourlevel of its own — one per level in
the ladder, whether or not the field crosses it — and puts the level's
curves inside as path.openline and path.closedline. A level the field
never reaches therefore still takes a group, which is why a curve is
addressed by the index of the LEVEL it runs at rather than by counting the
curves before it.
The trace's group is counted within its own panel, since plotly hangs no
uid class on these groups either.
Contour selectors: the curves plotly drew for one level at a time.
Plotly gives every level a
g.contourlevelof its own — one per level in the ladder, whether or not the field crosses it — and puts the level's curves inside aspath.openlineandpath.closedline. A level the field never reaches therefore still takes a group, which is why a curve is addressed by the index of the LEVEL it runs at rather than by counting the curves before it.The trace's group is counted within its own panel, since plotly hangs no uid class on these groups either.