get_levelpaths: Get Level Paths

Description Usage Arguments Details Value Examples

View source: R/get_paths.R

Description

Calculates level paths using the stream-leveling approach of NHD and NHDPlus. In addition to a levelpath identifier, a topological sort and levelpath outlet identifier is provided in output. If arbolate sum is provided in the weight column, this will match the behavior of NHDPlus. Any numeric value can be included in this column and the largest value will be followed when no nameID is available.

Usage

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get_levelpaths(x, override_factor = NULL, status = FALSE, cores = NULL)

Arguments

x

data.frame with ID, toID, nameID, and weight columns.

override_factor

numeric factor to use to override nameID. If 'weight' is 'numeric_factor' times larger on a path, it will be followed regardless of the nameID indication.

status

boolean if status updates should be printed.

cores

numeric number of cores to use in initial path ranking calculations.

Details

  1. levelpath provides an identifier for the collection of flowlines that make up the single mainstem flowpath of a total upstream aggregate catchment.

  2. outletID is the catchment ID (COMID in the case of NHDPlus) for the catchment at the outlet of the levelpath the catchment is part of.

  3. topo_sort is similar to Hydroseq in NHDPlus in that large topo_sort values are upstream of small topo_sort values. Note that there are many valid topological sort orders of a directed graph. The sort order output by this function is generated using 'igraph::topo_sort'.

Value

data.frame with ID, outletID, topo_sort, and levelpath columns. See details for more info.

Examples

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source(system.file("extdata", "walker_data.R", package = "nhdplusTools"))

test_flowline <- prepare_nhdplus(walker_flowline, 0, 0, FALSE)

test_flowline <- data.frame(
  ID = test_flowline$COMID,
  toID = test_flowline$toCOMID,
  nameID = walker_flowline$GNIS_ID,
  weight = walker_flowline$ArbolateSu,
  stringsAsFactors = FALSE)

get_levelpaths(test_flowline)

nhdplusTools documentation built on June 23, 2021, 9:07 a.m.