dodgr_times: Calculate matrix of pair-wise travel times between points.

In dodgr: Distances on Directed Graphs

Calculate matrix of pair-wise travel times between points.

Description

Calculates distances from input data.frame objects (graph), which must minimally contain three columns of from, to, and d or dist. If an additional column named weight or wt is present, shortest paths are calculated according to values specified in that column, while distances returned are calculated from the d or dist column. 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.

Graphs derived from Open Street Map street networks, via the weight_streetnet function, have columns labelled d, d_weighted, time, and time_weighted. For these inputs, paths between origin and destination points are always routed using d_weighted (or t_weighted for times), while final distances are sums of values of d (or t for times)- that is, of un-weighted distances or times - along those paths.

The function is parallelized for efficient computation of distances between multiple origin and destination points, as described in the from parameter below.

Usage

dodgr_times(
  graph,
  from = NULL,
  to = NULL,
  shortest = FALSE,
  pairwise = FALSE,
  heap = "BHeap"
)

Arguments

graph	data.frame or equivalent object representing the network graph (see Notes). For dodgr street networks, this may be a network derived from either sf or silicate ("sc") data, generated with weight_streetnet. 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.) Note that longitude and latitude values are always interpreted in 'dodgr' to be in EPSG:4326 / WSG84 coordinates. Any other kinds of coordinates should first be reprojected to EPSG:4326 before submitting to any 'dodgr' routines. See further information in Details.
from	Vector or matrix of points from which route distances are to be calculated, specified as one of the following: Single character vector precisely matching node numbers or names given in graph$from or graph$to. Single vector of integer-ish values, in which case these will be presumed to specify indices into dodgr_vertices, and NOT to correspond to values in the 'from' or 'to' columns of the graph. See the example below for a demonstration. Matrix or equivalent of longitude and latitude coordinates, in which case these will be matched on to the nearest coordinates of 'from' and 'to' points in the graph.
to	Vector or matrix of points to which route distances are to be calculated. If to is NULL, pairwise distances will be calculated from all from points to all other nodes in graph. If both from and to are NULL, pairwise distances are calculated between all nodes in graph.
shortest	If FALSE, calculate distances along the fastest rather than shortest routes. For street networks produced with weight_streetnet, distances may also be calculated along the fastest routes with the shortest = FALSE option. Graphs must in this case have columns of time and time_weighted. Note that the fastest routes will only be approximate when derived from sf-format data generated with the osmdata function osmdata_sf(), and will be much more accurate when derived from sc-format data generated with osmdata_sc(). See weight_streetnet for details.
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').

Value

square matrix of distances between nodes

See Also

Other distances: dodgr_distances(), dodgr_dists(), dodgr_dists_categorical(), dodgr_dists_nearest(), dodgr_paths(), dodgr_paths_expand()

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)

# Example of "from" and "to" as integer-ish values, in which case they are
# interpreted to index into "dodgr_vertices()":
graph <- data.frame (
    from = c (1, 3, 2, 2, 3, 3, 4, 4),
    to = c (2, 1, 3, 4, 2, 4, 3, 1),
    d = c (1, 2, 1, 3, 2, 1, 2, 1)
)
dodgr_dists (graph, from = 1, to = 2)
# That then gives distance from "1" to "3" because the vertices are built
# sequentially along "graph$from":
dodgr_vertices (graph)
# And vertex$id [2] is "3"

# 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/UrbanAnalyst/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)

## End(Not run)

dodgr documentation built on Sept. 3, 2026, 5:08 p.m.