Calculate Lookup Table Keys And Values

Description

Generates a new lookup table by evaluating two separate expressions once per row of a base lookup table — one expression for the output key and one for the output value. This allows complete transformation of a table's key-value structure, or construction of an entirely new lookup table row by row.

This functor is one of five in the calculator family. Use it when you need to recompute both the keys and the values of a lookup table. If only the values need to be recomputed and the keys should be inherited from the base table, use Calculate Lookup Table Values instead.

The abbreviated syntax (also called shorthand) for this functor is %%. See Calculator functor shorthand in the EGO Script documentation for the full syntax of both the verbose and abbreviated forms, and Calculate Functors — Complete Operator Documentation for the complete expression language reference.

Inputs

Name	Type	Description
Key Column Expression	Image Expression Type	The formula evaluated for each row to produce the output key, written using the image expression editor. Must be enclosed in square brackets [ ] in EGO Script.
Value Column Expression	Image Expression Type	The formula evaluated for each row to produce the output value, written using the image expression editor. Must be enclosed in square brackets [ ] in EGO Script.

Optional Inputs

Name	Type	Default	Description
Key Column Name	Name Type	None	Name of the key column in the output lookup table. If omitted, the corresponding name from the base table is used.
Value Column Name	Name Type	None	Name of the value column in the output lookup table. If omitted, the corresponding name from the base table is used.
Base Lookup Table	Lookup Table Type	None	The lookup table whose row set drives iteration. When not provided, the lowest-indexed connected Number Table (verbose form) or the first lookup table referenced by name in the expression (abbreviated form) is used — not a union of all connected tables.

Output

Name	Type	Description
Result	Lookup Table Type	A lookup table with both keys and values computed by the respective expressions.

Group

Table

Notes

Connecting data inputs

Tables, lookup tables, and scalar values referenced in either expression must be connected to the functor's ports before writing the expressions, using hook functors:

Tables and lookup tables → Number Table → referenced in the expression as t1, t2, …, t100

Scalar values → Number Value → referenced as v1, v2, …, v100

Maps cannot be connected — there is no cell context in this functor. In the abbreviated syntax, tables are referenced as %variableName and values as $variableName. Both expressions share the same set of connected operands.

Row iteration context

Both expressions are evaluated once per row of the base lookup table. Two keywords reflect the current row inside each expression:

line — the key of the current row

column — the value already associated with that key in the base lookup table

If the key expression produces a key that already exists in the output table, the newly computed value replaces the existing one.

Available expression features

Identical to Calculate Lookup Table Values: arithmetic and logical operators, scalar references (vX), lookup table queries (tX[...]) in all single-key and multi-column forms, and the line and column row-context keywords are available. Image operators (iX), neighbourhood functions, neighbourhood indexing, and convolution are not available. See The Expression Language for the complete reference, or Image Expression Type for the navigable operator index.

Null value handling

Null propagation rules and defensive patterns are covered in Null Value Handling in the Calculate Functors documentation.

Internal Name

CalculateLookupTableKeysAndValues