class_docstr: A histogram of a numerical 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
      bins (None): can be either an integer number of bins to generate or a
          monotonically increasing sequence specifying the bin edges to use.
          By default, 10 bins are created. If ``bins`` is an integer and no
          ``range`` is specified, bin edges are automatically computed from
          the bounds of the field
      range (None): a ``(lower, upper)`` tuple specifying a range in which to
          generate equal-width bins. Only applicable when ``bins`` is an
          integer or ``None``
      xlabel (None): an optional x-label for the plot
      log (False): whether to use a log scale y-axis
      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 _get_aggregations(self):
      return self._aggregations
  
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 4 for calling the NumericalHistogram obj's underlying member method code with example usage: obj._get_aggregations() and returns: self