Calculate isodistance or isochrone contours from specified points.

Returns lists of all network vertices contained within the contours. Function is fully vectorized to calculate accept vectors of central points and vectors defining multiple isochrone thresholds. Provide one or more dlim values for isodistances, or one or more tlim values for isochrones.

Usage

dodgr_isoverts(graph, from = NULL, dlim = NULL, tlim = NULL, heap = "BHeap")

Arguments

graph

data.frame or equivalent object representing the network graph. For dodgr street networks, this must be a network derived from silicate ("sc") data, generated with weight_streetnet. This function does not work with networks derived from sf data.

from

Vector or matrix of points from which isodistances or isochrones are to be calculated.

dlim

Vector of desired limits of isodistances in metres.

tlim

Vector of desired limits of isochrones in seconds

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

A single data.frame of vertex IDs, with columns denoting the from points and tlim value(s). The isochrones are given as id values and associated coordinates of the series of points from each from point at the specified isochrone times.

Isoverts are calculated by default using parallel computation with the maximal number of available cores or threads. This number can be reduced by specifying a value via RcppParallel::setThreadOptions (numThreads = <desired_number>).

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_paths(), dodgr_times()

Examples

if (FALSE) { # \dontrun{
# Use osmdata package to extract 'SC'-format data:
library (osmdata)
dat <- opq ("hampi india") %>%
    add_osm_feature (key = "highway") %>%
    osmdata_sc ()
graph <- weight_streetnet (dat)
from <- sample (graph$.vx0, size = 100)
tlim <- c (5, 10, 20, 30, 60) * 60 # times in seconds
x <- dodgr_isoverts (graph, from = from, tlim)
} # }