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Build the classification hierarchy of an expert system

resy_expert_tree.Rd

Turns the type definitions of a resy_expert object (Section 3, the "Group definitions") into a hierarchy.

With fill = FALSE (the default) the tree uses only the codes the expert defines: a definition nests under another when its code has that other code as its longest prefix among all codes present, so an EUNIS file with codes R, R1 and R12 nests R12 under R1 under R, while codes with no present prefix stay top-level. No levels are invented, which keeps the hierarchy faithful to files that define only a flat code list.

With fill = TRUE the intermediate group levels implied by the code grammar are reconstructed: each code is split into its ancestor path by code_path, and any ancestor the expert does not define is added as a structural group node (marked in the synthetic column). For EUNIS this yields a single tree rooted in the formation groups (M, N, Q, R, ...) with every type at its proper depth.

Usage

resy_expert_tree(
  expert,
  section = 3L,
  fill = FALSE,
  code_path = .resy_code_path,
  names = NULL
)

Arguments

expert

A resy_expert object from resy_read_expert, read with entries = TRUE (the default).

section

Integer; the section number holding the type definitions. Defaults to 3, the EUNIS-ESy convention.

fill

Logical; if TRUE, reconstruct the intermediate group levels implied by the codes. Defaults to FALSE.

code_path

Function mapping one code to the character vector of its ancestor codes from the root down to and including the code itself. Used only when fill = TRUE. The default splits a code into one level per character ("Q11" becomes c("Q", "Q1", "Q11"), "MA1" becomes c("M", "MA", "MA1")), which matches the EUNIS code grammar.

names

Optional code-to-name lookup used to label nodes that the expert leaves unnamed (typically the synthesised group levels). Either a named character vector (names are codes) or a data frame whose first two columns are code and name. resy_eunis_names returns the official EUNIS habitat names in this form. Defaults to NULL (no external names).

Value

An object of class resy_expert_tree: a data frame with one row per node and columns id, parent (NA for top-level nodes), code, description, priority, expression, level (1 for top-level nodes), leaf, synthetic (TRUE for a reconstructed group node the expert does not define) and name_source ("expert", "lookup" or ""). A print method renders it as an indented text tree.

See also

resy_write_expert_html and resy_view_expert to render the hierarchy as a self-contained interactive HTML page.

Examples

f <- system.file("extdata/classifications/Meadow-ESy-2025-01-18-2025.txt",
                 package = "RESY")
if (nzchar(f)) {
  expert <- resy_read_expert(f)
  print(resy_expert_tree(expert))            # codes as defined
  print(resy_expert_tree(expert, fill = TRUE)) # with group levels filled in
}