class_docstr: A histogram of a categorial field.
  
  Args:
      field_or_expr: a field name, ``embedded.field.name``,
          :class:`fiftyone.core.expressions.ViewExpression`, or
          `MongoDB expression <https://docs.mongodb.com/manual/meta/aggregation-quick-reference/#aggregation-expressions>`_
          defining the field or expression to plot
      expr (None): an optional
          :class:`fiftyone.core.expressions.ViewExpression` or
          `MongoDB expression <https://docs.mongodb.com/manual/meta/aggregation-quick-reference/#aggregation-expressions>`_
          to apply to ``field_or_expr`` (which must be a field) before
          plotting
      order ("alphabetical"): the x-axis ordering strategy to use. Can be
          "alphabetical" to sort by field value, or "frequency" to sort in
          descending order of frequency, or a function suitable for
          ``sorted(items, key=order)``, where ``items`` is a list of
          ``(value, count)`` tuples
      xlabel (None): an optional x-label for the plot
      log (False): whether to use a log scale y-axis
      bargap (None): relative spacing between bars in ``[0, 1]``
      color (None): a color for the bars. Can be any color supported by
          :meth:`plotly:plotly.graph_objects.bar.Marker.color`
      opacity (None): an optional opacity for the bars in ``[0, 1]``
      init_view (None): an optional initial
          :class:`fiftyone.core.collections.SampleCollection` to load
      **kwargs: optional parameters for
          :meth:`plotly:plotly.graph_objects.Figure.update_layout`
code: def _make_widget(self):
      return go.FigureWidget(self._figure)
  
imports: import itertools
  from operator import itemgetter
  import numpy
  import eta.core.utils
  import plotly.subplots
  import plotly.graph_objects
  import fiftyone.core.aggregations
  from .base import ViewPlot
  from .plotly import PlotlyWidgetMixin
label_desc: Use image node_id 2 for calling the CategoricalHistogram obj's underlying member method code with example usage: obj._make_widget() and returns: go