Build exclude_cats from event/split_event data

Returns a character vector of segment IDs that should be protected from collapse because they host (or are immediately downstream of) an event. Pass the result directly as the exclude_cats argument to refactor_flowlines().

Usage

events_to_exclude_cats(
  events = NULL,
  split_events = NULL,
  flowlines = NULL,
  protect_downstream = TRUE,
  only_split_candidates = FALSE
)

Arguments

events

sf or data.frame of events. Should have a flowpath_id column identifying the segment each event sits on.

split_events

sf or data.frame of split events. Also expected to have flowpath_id. When both events and split_events are provided, IDs from both are used.

flowlines

Optional sf or data.frame with flowpath topology columns (flowpath_id/flowpath_id and flowpath_toid/flowpath_toid). When supplied and protect_downstream = TRUE, the immediate downstream neighbor of each event-hosting segment is also included: matching the reference refactor-nhdplus behaviour which adds both the event flowpath_id and its flowpath_toid to exclude_cats.

protect_downstream

Logical (default TRUE). Include the downstream (toid) neighbor of each event segment when flowlines is provided.

only_split_candidates

Logical (default FALSE). When TRUE and split_events has a split_candidate column, restrict to rows where split_candidate == TRUE. Useful if only confirmed split-interior events should force protection.

Value

Named character vector of unique segment IDs to exclude from collapse.

Examples

if (FALSE) { # \dontrun{
excl <- events_to_exclude_cats(events    = poi_events,
                               flowlines = flines,
                               protect_downstream = TRUE)
refactor_flowlines(flines, split_flines_meters = 2000,
                   collapse_flines_meters = 1000,
                   out_refactored = "refactored.gpkg",
                   out_reconciled = "reconciled.gpkg",
                   exclude_cats = excl)
} # }