spath.lengths {streamDAG}

Shortest path lengths and number of paths

Description

The function spath.lengths calculates path lengths from all possible nodes to or from a designated node, i.e., the shortest in-paths and out-paths repsectively. Weighted path length are possible, including weighted path lengths based on field-observed instream arc lengths (see Examples). This results in "actual" path lengths in observed units. The function n.tot.paths calculates the total number of paths beginning or ending at all nodes in a graph, based on exponention of the the adjacency matrix.

Usage

spath.lengths(G, node = NULL, mode = "in", ignore.inf = TRUE)

n.tot.paths(G, mode = "in", sink = NULL)

Arguments

G

Graph of class "igraph". See graph_from_literal

node

Designated node.

mode

One of "in" or "out". The former gives in-paths, whereas the latter gives out-paths.

ignore.inf

Logical. Whether infinite distances are to be ignored. By default ignore.inf = TRUE, allowing impossible upstream distances to be ignored in stream DAGs.

sink

Name of sink node.

Value

Lengths of paths to a node of interest.

Author(s)

Ken Aho , Gabor Csardi wrote distances

Examples

data(mur_lengths)
mur <- streamDAGs("mur_full")
n.tot.paths(mur)

spath.lengths(mur, "M1653")
E(mur)$weight <- mur_lengths[,2] # weighted (actual in-stream lengths in meters)
spath.lengths(mur, "M1653")