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--- calculate_r_expression [2026/07/19 22:29]
hermann
+++ calculate_r_expression [2026/07/22 18:13] (current)
hermann
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 ===== Description =====
-This is a **[[ego_script#container_functors|container functor]]** that calls R externally, via the same [[external_communication|External Communication]] mechanism used by other integrations, and processes the script's outputs as if they were part of Dinamica EGO itself. Like the other calculator functors, data is connected through hook functors placed inside its ''<nowiki>{{ … }}</nowiki>'' block.
+This is a **[[ego_script#container_functors|container functor]]** that calls R externally with the user-defined expression. Like the other calculator functors, data is connected through hook functors placed inside its ''<nowiki>{{ … }}</nowiki>'' block.
 ===== Inputs =====
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 A **table** is transferred as a [[https://en.wikibooks.org/wiki/R_Programming/Working_with_data_frames|DataFrame]], with each column likewise accessed using ''$''. Two conventions apply to tables in either direction:
-  * **Key columns** are marked by an asterisk (''*'') appended to their column name — this is the same convention used throughout Dinamica EGO's table representation (see [[calculate_functors#connecting_data_inputs|Connecting Data Inputs]]).
+  * **Key columns** are marked by an asterisk (''*'') appended to their column name — this is the same convention used throughout Dinamica EGO's table representation (see [[calculate_functors#connecting_data_inputs|Connecting Data Inputs]]). A key column can be Real or String, the same as any other column.
-  * R automatically converts string columns to **Factors** inside a ''data.frame'', but Dinamica requires plain **Character Vectors**. Always build tables with ''stringsAsFactors = FALSE'' to prevent this conversion.
+  * Each column's type is inferred from its data, the same rule that applies to any table (see [[ego_script#constants|Constants]]): a numeric vector produces a Real column, a character vector produces a String column. R automatically converts string columns to **Factors** inside a ''data.frame'', and a Factor is neither of those — Dinamica requires plain **Character Vectors** to infer String correctly. Always build tables with ''stringsAsFactors = FALSE'' to prevent this conversion.
 For further detail on the underlying table representation, see [[external_communication#table|External Communication]].
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 | ''outputNumberVector()'' | Tuple | Accepts any collection of numbers. | ''outputNumberVector("myTuple", c(1:10))'' |
 | ''outputString()'' | String | Accepts any string value. | ''outputString("myString", "This is a string")'' |
-| ''outputLookupTable()'' | [[Lookup Table Type|Lookup Table]] | Requires two number vectors of equal length — one for the keys, one for the values. | ''outputLookupTable("myLUT", c(1:10), c(1:10) * 10)'' |
+| ''outputLookupTable()'' | [[Lookup Table Type|Lookup Table]] | Requires two number vectors of equal length — one for the keys, one for the values. Lookup tables are always Real-typed on both sides; there is no String option. | ''outputLookupTable("myLUT", c(1:10), c(1:10) * 10)'' |
 | ''outputTable()'' | Table | Requires a table built with the [[https://www.r-tutor.com/r-introduction/data-frame|data.frame]] function, using ''stringsAsFactors = FALSE'' as described above. Its optional second parameter (default ''1'') sets how many leading columns, from the left, are key columns. | ''outputTable("myTable", data.frame(State = c("Massachusetts", "Massachusetts"), City = c("Boston", "Chelsea"), Population = c(667137, 39398), stringsAsFactors = FALSE), 2)'' |
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 CalculateRExpression