get_DM {nhdplusTools}

Navigate Downstream Mainstem

Description

Traverse NHDPlus network downstream main stem

Usage

get_DM(network, comid, distance = NULL, sort = FALSE, include = TRUE)

Arguments

network

data.frame NHDPlus flowlines including at a minimum: COMID, LENGTHKM, DnHydroseq, and Hydroseq.

comid

integer identifier to start navigating from.

distance

numeric distance in km to limit how many COMIDs are returned. The COMID that exceeds the distance specified is returned.

sort

if TRUE, the returned COMID vector will be sorted in order of distance from the input COMID (nearest to farthest)

include

if TRUE, the input COMID will be included in the returned COMID vector

Value

integer vector of all COMIDs downstream of the starting COMID along the mainstem

Examples

library(sf)

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

plot(sample_flines$geom)
start_COMID <- 11690092
DM_COMIDs <- get_DM(sample_flines, start_COMID)
plot(dplyr::filter(sample_flines, COMID %in% DM_COMIDs)$geom,
     col = "red", add = TRUE, lwd = 3)

DM_COMIDs <- get_DM(sample_flines, start_COMID, distance = 40)
plot(dplyr::filter(sample_flines, COMID %in% DM_COMIDs)$geom,
     col = "blue", add = TRUE, lwd = 2)