dodgr (version 0.2.8)

dodgr_dists: dodgr_dists

Description

Calculate matrix of pair-wise distances between points.

Usage

dodgr_dists(
  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

# NOT RUN {
# 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 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`

# }
# NOT RUN {
# 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)
# }