init

NDPositions.init(ref_index, data, dims, display_dims, *args, graphic_type, slicer=NDPositionsSlicer, display_window=10, window_funcs=None, window_order=None, spatial_func=None, slider_maps=None, max_display_datapoints=1_000, datapoints_window_func=None, colors=None, cmap=None, cmap_transform=None, cmap_range=None, thickness=None, sizes=None, markers=None, graphic_kwargs=None, slicer_kwargs=None)

Set up the slicer and per-graphic state, i.e. everything except creating the graphic.

Separated from __init__ so NDTimeseries can run its own one-time setup between this and graphic creation.