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Build SQL predicates for one species' habitat classification

Source: R/frs_habitat_predicates.R
frs_habitat_predicates.Rd

Pure-R helper: takes one species' rules + ranges from frs_habitat_species() and returns a named list of SQL boolean expressions ("predicates") — the raw yes/no questions that frs_habitat_classify() embeds in CASE WHEN <pred> THEN TRUE ... to produce the per-species habitat columns.

Usage

frs_habitat_predicates(sp_params)

Arguments

sp_params

A single-species params list as produced by one element of frs_habitat_species(). Must contain species_code, spawn_gradient_min, spawn_gradient_max, ranges, optionally rules, optionally spawn_edge_types / rear_edge_types.

Value

A named list with four character scalars: spawn, rear, lake_rear, wetland_rear. Each is an SQL boolean expression suitable for embedding in CASE WHEN ... THEN TRUE ELSE FALSE END. Predicates reference the segmented streams alias s..

Details

Returns four predicates per call: spawn, rear, lake_rear, wetland_rear. Each is a fragment that references columns aliased as s. (the segmented streams table). Caller is responsible for embedding them in a complete query.

Two paths are supported, selected per habitat type by what's present in sp_params:

  1. Rules path — when sp_params$rules$<spawn|rear> is non-NULL, the rules YAML is compiled to SQL via .frs_rules_to_sql(). CSV thresholds (gradient + channel_width) are passed as the inheritance fallback for rules that omit explicit thresholds.

  2. CSV-ranges path — pre-rules behaviour. Builds the SQL directly from sp_params$ranges + sp_params$<spawn|rear>_edge_types.

Lake / wetland rearing predicates are gated on the presence of a waterbody_type: L / waterbody_type: W rule in rear:. Without the rule, the predicate is "FALSE" — the species is not lake or wetland-rearing. With the rule, an optional lake_ha_min / wetland_ha_min filters the polygon join.

Segments must still fall within the species' rear channel-width window for lake / wetland rearing.

See also

Other habitat: frs_aggregate(), frs_break(), frs_break_apply(), frs_break_find(), frs_break_validate(), frs_categorize(), frs_classify(), frs_cluster(), frs_col_generate(), frs_col_join(), frs_extract(), frs_feature_find(), frs_feature_index(), frs_habitat(), frs_habitat_access(), frs_habitat_classify(), frs_habitat_overlay(), frs_habitat_partition(), frs_habitat_species(), frs_network_segment()

Examples

if (FALSE) { # \dontrun{
params <- frs_params()
params_fresh <- read.csv(system.file("extdata",
  "parameters_fresh.csv", package = "fresh"))
species_params <- frs_habitat_species("CO", params, params_fresh)

preds <- frs_habitat_predicates(species_params[[1]])
preds$spawn
#> "s.gradient >= 0 AND s.gradient <= 0.0549 AND ..."
preds$lake_rear
#> "FALSE"  (CO has no waterbody_type: L rule under bcfishpass)
} # }