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Compute Pfafstetter basin codes over a directed acyclic network

Source: R/network_properties.R
get_pfafstetter.Rd

Assigns hierarchical Pfafstetter codes (the NHDPlus basin-coding scheme). At each level the basin's mainstem is found, its four largest tributaries (by total drainage area) are given even digits `2,4,6,8` ordered downstream to upstream, and the five mainstem inter-basins between those junctions take odd digits `1,3,5,7,9`. Each of the nine sub-basins is then subdivided the same way, appending a digit per level, down to `max_level`.

Usage

get_pfafstetter(
  x,
  id = "flowpath_id",
  toid = "flowpath_toid",
  total_da = "total_da_sqkm",
  topo_sort = "topo_sort",
  levelpath = "levelpath",
  max_level = 2
)

Arguments

x

A data frame with `id`, downstream pointer `toid`, `total_da` (total upstream drainage area), `topo_sort` (a hydrosequence; smaller is more downstream, e.g. from [get_hydroseq()]), and `levelpath` (e.g. from [get_levelpath()]). Terminal/outlet rows use `NA`, `""`, `"0"`, or an unknown `toid`.

id, toid

Column names. Default `"flowpath_id"` / `"flowpath_toid"`.

total_da, topo_sort, levelpath

Column names for total drainage area, hydrosequence, and level-path id. Defaults `"total_da_sqkm"`, `"topo_sort"`, `"levelpath"`.

max_level

Integer. Number of Pfafstetter levels (digits) to assign. Default `2`.

Value

Numeric vector of `max_level`-digit Pfafstetter codes aligned to the rows of `x`. Reaches whose sub-basin is deeper than `max_level` levels are `NA`.

Details

Requires the drainage-area, hydrosequence, and level-path columns to be precomputed (see [accumulate_downstream()], [get_hydroseq()], [get_levelpath()]); this keeps the coding independent of how those were derived. Ties in the four-largest-tributary cut are resolved by keeping all tied tributaries.

See also

Other network properties: accumulate_downstream(), get_hydroseq(), get_levelpath(), get_pathlength(), get_streamlevel(), get_streamorder(), hf_upstream_index(), merge_groups(), upstream_index()

Examples

if (FALSE) { # \dontrun{
x$total_da_sqkm <- accumulate_downstream(x, attr = "areasqkm")
x$topo_sort     <- get_hydroseq(x)
x$levelpath     <- get_levelpath(x, weight = "total_da_sqkm")
x$pfaf          <- get_pfafstetter(x, max_level = 2)
} # }