dodgr_distances

Alias for dodgr_dists

dodgr_distances(
  graph,
  from = NULL,
  to = NULL,
  shortest = TRUE,
  pairwise = FALSE,
  heap = "BHeap",
  parallel = TRUE,
  quiet = TRUE
)

Arguments

graph	data.frame or equivalent object representing the network graph (see Notes)
from	Vector or matrix of points from which route distances are to be calculated (see Notes)
to	Vector or matrix of points to which route distances are to be calculated (see Notes)
shortest	If FALSE, calculate distances along the fastest rather than shortest routes (see Notes).
pairwise	If TRUE, calculate distances only between the ordered pairs of from and to.
heap	Type of heap to use in priority queue. Options include Fibonacci Heap (default; FHeap), Binary Heap (BHeap), Trinomial Heap (TriHeap), Extended Trinomial Heap (TriHeapExt, and 2-3 Heap (Heap23`).
parallel	If TRUE, perform routing calculation in parallel (see details)
quiet	If FALSE, display progress messages on screen.

Value

square matrix of distances between nodes

Examples

# A simple graph
graph <- data.frame (from = c ("A", "B", "B", "B", "C", "C", "D", "D"),
                     to = c ("B", "A", "C", "D", "B", "D", "C", "A"),
                     d = c (1, 2, 1, 3, 2, 1, 2, 1))
dodgr_dists (graph)
#>   A B C D
#> A 0 1 2 3
#> B 2 0 1 2
#> C 2 2 0 1
#> D 1 2 2 0

# A larger example from the included [hampi()] data.
graph <- weight_streetnet (hampi)
from <- sample (graph$from_id, size = 100)
to <- sample (graph$to_id, size = 50)
d <- dodgr_dists (graph, from = from, to = to)
# d is a 100-by-50 matrix of distances between `from` and `to`

if (FALSE) {
# a more complex street network example, thanks to @chrijo; see
# https://github.com/ATFutures/dodgr/issues/47

xy <- rbind (c (7.005994, 51.45774), # limbeckerplatz 1 essen germany
             c (7.012874, 51.45041)) # hauptbahnhof essen germany
xy <- data.frame (lon = xy [, 1], lat = xy [, 2])
essen <- dodgr_streetnet (pts = xy, expand = 0.2, quiet = FALSE)
graph <- weight_streetnet (essen, wt_profile = "foot")
d <- dodgr_dists (graph, from = xy, to = xy)
# First reason why this does not work is because the graph has multiple,
# disconnected components.
table (graph$component)
# reduce to largest connected component, which is always number 1
graph <- graph [which (graph$component == 1), ]
d <- dodgr_dists (graph, from = xy, to = xy)
# should work, but even then note that
table (essen$level)
# There are parts of the network on different building levels (because of
# shopping malls and the like). These may or may not be connected, so it may
# be necessary to filter out particular levels
index <- which (! (essen$level == "-1" | essen$level == "1")) # for example
library (sf) # needed for following sub-select operation
essen <- essen [index, ]
graph <- weight_streetnet (essen, wt_profile = "foot")
graph <- graph [which (graph$component == 1), ]
d <- dodgr_dists (graph, from = xy, to = xy)
}