dodgr_paths: Calculate lists of pair-wise shortest paths between points.

In dodgr: Distances on Directed Graphs

Calculate lists of pair-wise shortest paths between points.

Description

Calculate lists of pair-wise shortest paths between points.

Usage

dodgr_paths(
  graph,
  from,
  to,
  vertices = TRUE,
  pairwise = FALSE,
  heap = "BHeap",
  quiet = TRUE
)

Arguments

graph	data.frame or equivalent object representing the network graph (see Details)
from	Vector or matrix of points from which route paths are to be calculated (see Details)
to	Vector or matrix of points to which route paths are to be calculated (see Details)
vertices	If TRUE, return lists of lists of vertices for each path, otherwise return corresponding lists of edge numbers from graph.
pairwise	If TRUE, calculate paths only between the ordered pairs of from and to. In this case, each of these must be the same length, and the output will contain paths the i-th members of each, and thus also be of that length.
heap	Type of heap to use in priority queue. Options include Fibonacci Heap (default; FHeap), Binary Heap (BHeap), Radix, Trinomial Heap (TriHeap), Extended Trinomial Heap (TriHeapExt, and 2-3 Heap (Heap23).
quiet	If FALSE, display progress messages on screen.

Value

List of list of paths tracing all connections between nodes such that if x <- dodgr_paths (graph, from, to), then the path between from[i] and to[j] is x [[i]] [[j]]. Each individual path is then a vector of integers indexing into the rows of graph if vertices = FALSE, or into the rows of dodgr_vertices (graph) if vertices = TRUE.

Note

graph must minimally contain four columns of from, to, dist. If an additional column named weight or wt is present, shortest paths are calculated according to values specified in that column; otherwise according to dist values. Either way, final distances between from and to points are calculated according to values of dist. That is, paths between any pair of points will be calculated according to the minimal total sum of weight values (if present), while reported distances will be total sums of dist values.

The from and to columns of graph may be either single columns of numeric or character values specifying the numbers or names of graph vertices, or combinations to two columns specifying geographical (longitude and latitude) coordinates. In the latter case, almost any sensible combination of names will be accepted (for example, ⁠fromx, fromy⁠, ⁠from_x, from_y⁠, or ⁠fr_lat, fr_lon⁠.)

from and to values can be either two-column matrices of equivalent of longitude and latitude coordinates, or else single columns precisely matching node numbers or names given in graph$from or graph$to. If to is missing, pairwise distances are calculated between all points specified in from. If neither from nor to are specified, pairwise distances are calculated between all nodes in graph.

See Also

Other distances: dodgr_distances(), dodgr_dists(), dodgr_dists_categorical(), dodgr_dists_nearest(), dodgr_flows_aggregate(), dodgr_flows_disperse(), dodgr_flows_si(), dodgr_isochrones(), dodgr_isodists(), dodgr_isoverts(), dodgr_times()

Examples

graph <- weight_streetnet (hampi)
from <- sample (graph$from_id, size = 100)
to <- sample (graph$to_id, size = 50)
dp <- dodgr_paths (graph, from = from, to = to)
# dp is a list with 100 items, and each of those 100 items has 30 items, each
# of which is a single path listing all vertiex IDs as taken from `graph`.

# it is also possible to calculate paths between pairwise start and end
# points
from <- sample (graph$from_id, size = 5)
to <- sample (graph$to_id, size = 5)
dp <- dodgr_paths (graph, from = from, to = to, pairwise = TRUE)
# dp is a list of 5 items, each of which just has a single path between each
# pairwise from and to point.

dodgr documentation built on Sept. 11, 2024, 7:52 p.m.