upstream: Upstream River Distance

Description

Calculates river network distances as +/-, defined as upriver/downriver.

Specifying net=TRUE will compute net upriver distance (3 river km down a tributary and then 15 river km up the mainstem will mean 12 rkm net. Otherwise the function will return 18 rkm upriver travel.)

The mouth (lowest point) segment and vertex must be specified (see setmouth).

Usage

upstream(
  startseg,
  endseg,
  startvert,
  endvert,
  rivers,
  flowconnected = FALSE,
  net = FALSE,
  stopiferror = TRUE,
  algorithm = NULL
)

Value

Upstream distance (numeric). Returns NA if flowconnected has value TRUE and the two segments are not flow-connected.

Arguments

startseg: Segment number of the start of the route
endseg: Segment number of the end of the route
startvert: Vertex number of the start of the route
endvert: Vertex number of the end of the route
rivers: The river network object to use
flowconnected: If TRUE, only returns distance if the two input segments are flow-connected. Defaults to FALSE.
net: Whether to calculate net distance (net=TRUE) or total distance (net=FALSE)
stopiferror: Whether or not to exit with an error if a route cannot be found. If this is set to FALSE and a route cannot be found, the function will return NA in the appropriate entry. Defaults to TRUE. See detectroute.
algorithm: Which route detection algorithm to use ("Dijkstra", "sequential", or "segroutes"). If left as NULL (the default), the function will automatically make a selection. See detectroute for more details.

Author

Matt Tyers

Examples

Run this code

data(Gulk)

# Mouth must be specified
Gulk$mouth$mouth.seg <- 1
Gulk$mouth$mouth.vert <- 1

plot(x=Gulk)
riverpoints(seg=c(6,4), vert=c(140,140), pch=16, col=2, rivers=Gulk)
upstream(startseg=6, endseg=4, startvert=140, endvert=40, rivers=Gulk, net=TRUE)
upstream(startseg=6, endseg=4, startvert=140, endvert=40, rivers=Gulk, net=FALSE)
upstream(startseg=6, endseg=4, startvert=140, endvert=40, rivers=Gulk, flowconnected=TRUE)