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calculate_categorical_map [2012/03/14 21:25] hermann |
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]]). |
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| + | 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. | ||
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| + | 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 | Default((Based on the value of the Cell Type input.)) | | + | | 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. | + | ===== Internal Name ===== |
| - | 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]]. | + | ''CalculateCategoricalMap'' |
| - | 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]]. | ||
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| - | ===== Internal Name ===== | ||
| - | CalculateCategoricalMap | ||