safe_topological_sort: Safe Wrapper for Topological Sort

In REDCapCAST: REDCap Metadata Casting and Castellated Data Handling

Safe Wrapper for Topological Sort

Description

Calls topological_sort and falls back to elements in order of first appearance if a cycle makes a valid ordering impossible. Guaranteed to always return a character vector of all unique elements.

Usage

safe_topological_sort(
  ordered_list,
  priority = c("none", "lexicographic", "least_constrained", "most_constrained")
)

Arguments

ordered_list

A list of character vectors, each specifying a partial ordering of elements. Consecutive elements within a vector imply a precedence constraint: earlier elements must appear before later ones in the output. Elements may appear across multiple vectors; constraints from all vectors are combined. Duplicate constraints are silently ignored.

priority

A string controlling how ties are broken when multiple elements are simultaneously eligible for placement. One of: "none" Default. Eligible elements are processed in the order they are first encountered in ordered_list. Fully deterministic with no resorting overhead. "lexicographic" Eligible elements are sorted alphabetically by name. Useful for reproducible output independent of input order. "least_constrained" Eligible elements with the fewest total edges (in-degree + out-degree) are placed first. Elements that participate in fewer ordering relationships surface earlier. "most_constrained" Eligible elements with the most total edges (in-degree + out-degree) are placed first. Elements that participate in more ordering relationships surface earlier.

Value

A character vector of all unique elements from ordered_list. If constraints are consistent, the order satisfies all precedence constraints as per topological_sort. If a cycle is detected, elements are returned in order of first appearance in ordered_list.

See Also

topological_sort

REDCapCAST documentation built on Oct. 29, 2026, 5:08 p.m.