====== Get Map Categories ====== 

===== Description =====

This functor extracts the set of categories from the input map. 

===== Inputs =====

^ Name ^ Type ^ Description ^
| Categorical Map  | [[Map Type]]  | Map with the required categories.  |

===== Optional Inputs =====

===== Outputs =====

^ Name ^ Type ^ Description ^
| Categories | [[Categorization Type]]  | The category set of the input map.  |

===== Group =====

[[Functor List#Map Algebra | Map Algebra]]

===== Notes =====

An error is always reported, if the input map does not provide the definition of any categories, an error is reported.

If necessary, use a [[Skip All On Error]] to intercept and trap the error and a [[Calculate Categorical Map]] to generate the map categories from the input map.

===== Internal Name ===== 

GetMapCategories