class_docstr: Calculate the `median absolute deviation <https://en.wikipedia.org/wiki/Median_absolute_deviation>`_
  of a column.
  
  :param column_name:
      The name of a column containing :class:`.Number` data.
class_docstr_tok: ["Calculate","the","`","median","absolute","deviation","<","https",":","\/\/en.wikipedia.org\/wiki\/Median_absolute_deviation",">","`","_","of","a","column",".",":","param","column_name",":","The","name","of","a","column","containing",":","class",":","`",".Number","`","data","."]
code: def __init__(self, column_name):
      self._column_name = column_name
      self._median = Median(column_name)
  
file_path: agate/agate/aggregations/mad.py
imports: from agate.aggregations.base import Aggregation
  from agate.aggregations.has_nulls import HasNulls
  from agate.aggregations.median import Median
  from agate.data_types import Number
  from agate.exceptions import DataTypeError
  from agate.utils import median
  from agate.warns import warn_null_calculation
label_desc: Use image node_id 1 to create a new MAD object from inherited base classes: Aggregation with example: obj = MAD(column_name)