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calculate_map [2026/07/04 23:01] hermann |
calculate_map [2026/07/15 01:17] (current) hermann |
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| Computes a new **continuous raster map** by evaluating an algebraic or logical expression independently for every cell in the output map. The expression result is always computed as a real (floating-point) value and then converted to the output map's chosen Cell Type. | Computes a new **continuous raster map** by evaluating an algebraic or logical expression independently for every cell in the output map. The expression result is always computed as a real (floating-point) value and then converted to the output map's chosen Cell Type. | ||
| - | [[Calculate Map]] is one of five functors in the [[calculate_functors|calculator family]]. Use it when the expression produces continuous or measured values. If the expression produces integer class codes that should be treated as categories by downstream functors, use [[Calculate Categorical Map]] instead. | + | This functor is one of five in the [[calculate_functors|calculator family]]. Use it when the expression produces continuous or measured values. If the expression produces integer class codes that should be treated as categories by downstream functors, use [[Calculate Categorical 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. | 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. | ||
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| ^ Name ^ Type ^ Description ^ | ^ Name ^ Type ^ Description ^ | ||
| - | | Expression | [[Image Expression Type]] | The algebraic or logical formula used to compute each output cell, written using the [[Image Expression Type|image expression editor]]. Must be enclosed in square brackets ''[ ]'' in EGO Script. | | + | | Expression | [[Image Expression Type]] | The algebraic or logical formula used to compute each output cell. Must be enclosed in square brackets ''[ ]'' in EGO Script. | |
| ===== Optional Inputs ===== | ===== Optional Inputs ===== | ||
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| | Null Value | [[Null Value Type]] | Based on Cell Type | Sentinel value representing "no data" in the output. | | | Null Value | [[Null Value Type]] | Based on Cell Type | Sentinel value representing "no data" in the output. | | ||
| | Result Is Sparse | [[Boolean Value Type]] | False | If true, only non-null cells are stored in memory — saves memory but slows random access. | | | 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. | | + | | 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 ===== | ||
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| When the expression references more than one map, all of them are evaluated at the **same current cell** — ''i1'' and ''i2'' always refer to the same spatial location. Connected maps do **not** need matching extent, resolution, or pixel dimensions: Dinamica EGO reconciles this automatically through **image virtualization**, transparently wrapping each input in a virtual version sharing a common extent and the highest resolution among the inputs. The one requirement that virtualization does not relax is **projection** — all connected maps must share the same projection. | When the expression references more than one map, all of them are evaluated at the **same current cell** — ''i1'' and ''i2'' always refer to the same spatial location. Connected maps do **not** need matching extent, resolution, or pixel dimensions: Dinamica EGO reconciles this automatically through **image virtualization**, transparently wrapping each input in a virtual version sharing a common extent and the highest resolution among the inputs. The one requirement that virtualization does not relax is **projection** — all connected maps must share the same projection. | ||
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| + | The ''iX[LINE, COL]'' form samples a map at an explicit coordinate rather than the current cell. Coordinates outside the image boundary are **mirrored** back into range. For a row coordinate ''cellLine'' in an image of N rows, ''cellLine'' is normally expected to be in the range [1, N]. When ''cellLine'' is outside this range, it is mirrored back: if ''cellLine'' ≤ 0, the effective row is ''1 − cellLine'' (for instance, ''cellLine'' = 0 → row 1, ''cellLine'' = −1 → row 2, ''cellLine'' = −2 → row 3); if ''cellLine'' > N, the effective row is ''2N + 1 − cellLine'' (for instance, ''cellLine'' = N+1 → row N, ''cellLine'' = N+2 → row N−1, ''cellLine'' = N+3 → row N−2). The same formula applies independently to the column coordinate ''cellCol''. If the target cell is null, the result is 0 rather than null. | ||
| ==== Available expression features ==== | ==== Available expression features ==== | ||
| - | All expression language features are available in [[Calculate Map]] — there are no restrictions. For the full operator reference, see [[calculate_functors#the_expression_language|The Expression Language]] in the Calculate Functors documentation, or the [[Image Expression Type]] page for the GUI editor and a navigable operator index. | + | All expression language features are available — there are no restrictions. For the full operator reference, see [[calculate_functors#the_expression_language|The Expression Language]] in the Calculate Functors documentation, or the [[Image Expression Type]] page for the GUI editor and a navigable operator index. |
| ==== Null value handling ==== | ==== Null value handling ==== | ||