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Subset a NextGen HydroFabric from either a GPKG or layered Hive-partitioned GeoParquets

Source: R/subsetter.R
hfsubset.Rd

Given a HydroFabric store and an origin identifier (by flowpath_id, by an external comid, or by an hl_reference tag), build an upstream subgraph and return/write filtered layers.

Usage

hfsubset(
  src,
  id,
  comid,
  hl_reference,
  gage,
  xy,
  outfile = NULL,
  lyrs = c("flowpaths", "flowlines", "divides", "nexus", "network", "hydrolocations",
    "pois", "flowpath-attributes", "divide-attributes"),
  crs = NULL,
  verbose = FALSE,
  check = FALSE,
  cache = TRUE,
  optimize = TRUE
)

Arguments

src

Path to a GeoPackage (.gpkg) OR the root directory of layered hive-partitioned GeoParquet (e.g., //v1/vpu=01/part-*.parquet). The store type (GeoPackage vs GeoParquet) is inferred from src.

id

Origin flowpath_id (character).

comid

Origin NHDPlusV2 COMID.

hl_reference

Origin hl_reference tag (e.g. nwis-09112500).

gage

Origin USGS gage id (e.g. "09112500"). Convenience for hl_reference = paste0("nwis-", gage); an 8-digit id is expected.

xy

Origin point as c(x, y) (defaults to lon/lat, EPSG:4326). Resolved to the containing divide, then to its flowpath. Uses the GPKG R-tree on OGR stores; reads the full divides layer otherwise.

outfile

Optional path to write the subset to a new GeoPackage.

lyrs

Character vector of layer names to extract. Defaults to c("flowpaths","divides","nexus","network","hydrolocations","pois", "flowpath-attributes","divide-attributes").

crs

Optional EPSG/int for sf outputs when reading GeoParquet (recommended if CRS missing).

verbose

Logical. Emit progress messages. Default FALSE.

check

Logical. If TRUE, run hfutils::hf_check_invariants("ngen", ...) on the returned subset (warnings only, does not stop). Default FALSE.

cache

Logical. Reuse an in-memory per-VPU network graph across calls (big win for batch subsetting). Default TRUE. See hfsubset_clear_cache().

optimize

Logical. When writing outfile, index and optimize the GeoPackage via optimize_gpkg(). Default TRUE.

Value

A named list of tibbles/sf if outfile is missing; invisibly the list after writing otherwise.