====== Extract Categorical Map Attributes ======

===== Description =====

Calculates basic statistics from a map for each class delimited by a categorical map, returning them as a table indexed jointly by attribute and class. All layers of the map are analyzed together, and the resulting table refers to them jointly.

===== Inputs =====

^ Name  ^ Type  ^ Description  ^
| Map  | [[Map Type]]  | Map whose attributes will be extracted.  |
| Categorical Map  | [[Categorical Map Type]]  | Map of classes used to delimit the calculation area for each class in Map.  |

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

^ Name  ^ Type  ^ Description  ^ Default Value  ^
| Extract Statistical Attributes  | [[Boolean Value Type]]  | If true, statistical attributes (mean, variance, standard deviation, mode, median, unique count) are also extracted.  | Yes  |

===== Outputs =====

^ Name  ^ Type  ^ Description  ^
| Attributes  | [[Table Type]]  | Table of extracted attributes, keyed by attribute and by class.  |

===== Group =====

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

===== Notes =====

Attributes has columns "Attribute" (key, the attribute's numeric code) and "Category" (key, the class value from Categorical Map), with the corresponding statistic in the "Value" data column.

Each attribute has a predefined name that can be used to retrieve it by name (rather than by numeric key) in [[Calculate Map]], [[Calculate Categorical Map]], [[Calculate Value]], and the lookup table calculators.

If an attribute cannot be determined for a class, its entry is omitted from Attributes rather than being filled with a placeholder. Minimum and maximum values are only determined when the class has at least one non-null cell.

Dynamic attributes, computed across all non-null cells of all layers within each class:

^ Key  ^ Predefined Name  ^ Description  ^
| 8  | "nullCells"  | number of null cells  |
| 9  | "nonNullCells"  | number of non-null cells  |
| 10  | "minCell"  | minimum value (excluding null cells)  |
| 11  | "maxCell"  | maximum value (excluding null cells)  |
| 12  | "cellSum"  | sum of the values (excluding null cells)  |

Statistical attributes (present only when Extract Statistical Attributes is true), computed across all non-null cells of all layers within each class:

^ Key  ^ Predefined Name  ^ Description  ^
| 13  | "meanCell"  | average (excluding null cells)  |
| 14  | "cellVar"  | variance (excluding null cells)  |
| 15  | "cellStd"  | standard deviation (excluding null cells)  |
| 16  | "modeCell"  | mode (excluding null cells)  |
| 17  | "medianCell"  | median (excluding null cells)  |
| 18  | "uniqueCells"  | total unique occurrences (excluding null cells)  |

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

ExtractCategoricalMapAttributes