docstr: Create dictionary containing default ColumnDataSource glyph to data
  mappings.
code: def get_default_mapping(self, z, cmapper):
      """Create dictionary containing default ColumnDataSource glyph to data
      mappings.
  
      """
  
      map_annular = dict(
          x=self.max_radius,
          y=self.max_radius,
          inner_radius="inner_radius",
          outer_radius="outer_radius",
          start_angle="start_angle",
          end_angle="end_angle",
          fill_color={"field": z, "transform": cmapper},
      )
  
      map_seg_label = dict(
          x="x", y="y", text="text", angle="angle", text_align="center"
      )
  
      map_ann_label = dict(
          x="x",
          y="y",
          text="text",
          angle="angle",
          text_align="center",
          text_baseline="bottom",
      )
  
      map_xmarks = dict(xs="xs", ys="ys")
  
      map_ymarks = dict(
          x=self.max_radius,
          y=self.max_radius,
          start_angle=0,
          end_angle=2 * np.pi,
          radius="radius",
      )
  
      return {
          "annular_wedge_1": map_annular,
          "text_1": map_seg_label,
          "text_2": map_ann_label,
          "multi_line_1": map_xmarks,
          "arc_1": map_ymarks,
      }
  
imports: import numpy
  import param
  from bokeh.models.glyphs import AnnularWedge
  from ...core.data import GridInterface
  from ...core.spaces import HoloMap
  from ...core.util import dimension_sanitizer, is_nan
  from .element import ColorbarPlot, CompositeElementPlot
  from .selection import BokehOverlaySelectionDisplay
  from .styles import base_properties, fill_properties, line_properties, text_properties
label_desc: Use image node_id 8 for calling the RadialHeatMapPlot obj's underlying member method code with example usage: obj.get_default_mapping(z, cmapper) and returns: dict