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Index Upstream/Downstream Features for Stream Segments

Source: R/frs_feature_index.R
frs_feature_index.Rd

For each segment in a stream table, find which features from a feature table are upstream or downstream on the network. Stores results as feature ID arrays — enabling queries like "which crossings are between this segment and the ocean?"

Usage

frs_feature_index(
  conn,
  segments,
  features,
  direction = "downstream",
  col_segment_id = "id_segment",
  col_feature_id = "feature_id",
  to = "working.feature_index",
  label_filter = NULL,
  overwrite = TRUE,
  verbose = TRUE
)

Arguments

conn

A DBI::DBIConnection object.

segments

Character. Schema-qualified segmented streams table (from frs_network_segment()).

features

Character. Schema-qualified feature table (from frs_feature_find()).

direction

Character. "downstream" (features between segment and ocean) or "upstream" (features above segment). Default "downstream".

col_segment_id

Character. Segment ID column. Default "id_segment".

col_feature_id

Character. Feature ID column. Default "feature_id". If the feature table has no ID column, uses row position.

to

Character. Output table name. Default "working.feature_index".

label_filter

Character or NULL. SQL predicate to filter features by label before indexing (e.g. "label = 'blocked'").

overwrite

Logical. Drop to before creating. Default TRUE.

verbose

Logical. Print progress. Default TRUE.

Value

conn invisibly, for pipe chaining.

Details

Uses fwa_upstream() or fwa_downstream() for network-aware traversal via ltree codes.

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_habitat(), frs_habitat_access(), frs_habitat_classify(), frs_habitat_overlay(), frs_habitat_partition(), frs_habitat_predicates(), frs_habitat_species(), frs_network_segment()

Examples

if (FALSE) { # \dontrun{
conn <- frs_db_conn()

# Which crossings are downstream of each segment?
frs_feature_index(conn,
  segments = "fresh.streams",
  features = "working.features_crossings",
  direction = "downstream",
  to = "working.crossings_dnstr")

# Query: segments with confirmed barriers downstream
DBI::dbGetQuery(conn, "
  SELECT s.id_segment, i.features_dnstr
  FROM fresh.streams s
  JOIN working.crossings_dnstr i ON s.id_segment = i.id_segment
  WHERE array_length(i.features_dnstr, 1) > 0
  LIMIT 10")

# Fish observations upstream of each segment
frs_feature_index(conn,
  segments = "fresh.streams",
  features = "working.features_fish_obs",
  direction = "upstream",
  col_feature_id = "fish_observation_point_id",
  to = "working.fish_obs_upstr")

DBI::dbDisconnect(conn)
} # }