#### 8.2.6 categorical ¶

Class: categorical ¶

  Categorical variable array.

  A `categorical` array represents an array of values of a categorical variable. Each `categorical` array stores the element values along with a list of the categories, and indicators of whether the categories are ordinal (that is, they have a meaningful mathematical ordering), and whether the set of categories is protected (preventing new categories from being added to the array).

  In addition to the categories defined in the array, a categorical array may have elements of "undefined" value. This is not considered a category; rather, it is the absence of any known value. It is analagous to a `NaN` value.

  This class is not fully implemented yet. Missing stuff:

  - gt, ge, lt, le
  - Ordinal support in general
  - countcats
  - summary

Instance Variable of `categorical`: ``uint16`` code ¶

  The numeric codes of the array element values. These are indexes into the `cats` category list.

  This is a planar property.

Instance Variable of `categorical`: ``logical`` tfMissing ¶

  A logical mask indicating whether each element of the array is missing (that is, undefined).

  This is a planar property.

Instance Variable of `categorical`: ``cellstr`` cats ¶

  The names of the categories in this array. This is the list into which the `code` values are indexes.

Instance Variable of `categorical`: ``scalar_logical`` isOrdinal ¶

  A scalar logical indicating whether the categories in this array have an ordinal relationship.