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calculate_categorical_map [2011/07/25 01:30]
hermann created 		calculate_categorical_map [2026/07/15 01:19] (current)
hermann
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 ===== Description ===== ===== Description =====
  
-This container calculates ​a categorical map using algebraic/logical expression ​involving maps, tables ​and values.+Computes ​a new **categorical ​raster ​map** by evaluating an algebraic ​or logical expression ​independently for every cell in the output map. Functionally identical to [[Calculate Map]] — the same inputs, parameters, and expression language apply — but the output is typed as a categorical map, which preserves category semantics for downstream functors that distinguish categorical maps from continuous maps (e.g. [[Calc Areas]], [[For Each Category]]). 
 + 
 +Use this functor when the expression produces integer class codes rather than measured or continuous ​values. If the expression produces continuous or measured values, use [[Calculate Map]] instead. 
 + 
 +The **abbreviated syntax** (also called **shorthand**) for this functor is ''##''​. See [[ego_script#​calculator_functor_shorthand|Calculator functor shorthand]] in the EGO Script documentation for the full syntax of both the verbose and abbreviated forms, and [[calculate_functors|Calculate Functors — Complete Operator Documentation]] for the complete expression language reference.
  
 ===== Inputs ===== ===== Inputs =====
  
-^ Name       ​^ Type                                         ​^ Description ​                                                      ​^ +^ Name ^ Type ^ Description ^ 
-| Expression | [[Image Expression Type | Image Expression]] | Algebraic ​or logical ​expression ​used to calculate the output ​map. |+| Expression | [[Image Expression Type]] | The algebraic ​or logical ​formula ​used to compute each output ​cell's category code. Must be enclosed in square brackets ''​[ ]''​ in EGO Script. |
  
 ===== Optional Inputs ===== ===== Optional Inputs =====
  
-^ Name             ​^ Type                           ​^ Description ​                                                                                                                                                                          ^ Default Value         ^ +^ Name ^ Type ^ Default ​^ Description ^ 
-| Cell Type        | [[Cell Type Type | Cell Type]] ​| Data cell type                                                                                                                                                                        ​| Signed 32 Bit Integer | +| Cell Type | [[Cell Type Type]] | Signed 32-bit Integer ​| Data type for each output cell. | 
-| Null Value       ​| [[Int Type | Int]]             ​| Null value                                                                                                                                                                            ​| -2147483648 ​          | +| Null Value | [[Null Value Type]] | Based on Cell Type | Sentinel value representing "no data" in the output. ​| 
-| Result Is Sparse | [[Bool Type | Bool]]           ​| If true, the resulting map is created as a sparse image. Sparse images have the advantage of storing ​only the cells containing ​non-null ​values, ​but they have diminished ​access ​time. | False                 |+| Result Is Sparse | [[Boolean Value Type]] ​| False | If true, only non-null ​cells are stored in memory — saves memory ​but slows random ​access. | 
 +| Result Format | [[Map Type]] | None | Optional reference map whose spatial format (extent, resolution, projection) is applied to the output. Category information in the reference map is ignored. Prefer this port over a ''​Number Map''​ hook when the map is needed only for format purposes — a hook defines an identifier in the expression namespace and blocks abbreviated syntax if that identifier is unused in the expression. ​|
  
 ===== Outputs ===== ===== Outputs =====
  
-^ Name   ​^ Type                                       ​^ Description ​                        ​^ +^ Name ^ Type ^ Description ^ 
-| Result | [[Categorical Map Type | Categorical Map]] | Output ​map of classes or categories ​|+| Result | [[Categorical Map Type]] | The computed categorical output ​map. |
  
 ===== Group ===== ===== Group =====
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 ===== Notes ===== ===== Notes =====
  
-The expression ​result is calculated as a real value and converted ​to the data cell type of the output map.+All behaviour — hook functor wiring, spatial context, image virtualization,​ available ​expression ​features, null value handling, ​and performance — is identical ​to [[Calculate Map]]. See the [[Calculate Map#​notes|Notes]] section ​of that page for full details.
  
-If the calculation of the expression diverges or if the data cell type is not large enough, the corresponding cell is filled with the null value. 
- 
-The list of mathematical and logical operators that can be employed in the logic/​algebraic expression can be found in the [[Image Expression Type | image expression reference]]. 
- 
-The maps used by the "​Calculate Categorical Map" must be provided by a corresponding [[Number Map]], the tables must be provided by a corresponding [[Number Table]] and the values must be provided by a corresponding [[Number Value]]. 
-  
 ===== Internal Name ===== ===== Internal Name =====
  
-CalculateCategoricalMap+''​CalculateCategoricalMap''​