get_isochrone: Compute isochrones/isodistances from nodes.

In cppRouting: Algorithms for Routing and Solving the Traffic Assignment Problem

Compute isochrones/isodistances from nodes.

Description

Compute isochrones/isodistances from nodes.

Usage

get_isochrone(Graph, from, lim, setdif = FALSE, keep = NULL, long = FALSE)

Arguments

Graph	An object generated by makegraph or cpp_simplify function.
from	numeric or character. A vector of one or more vertices from which isochrones/isodistances are calculated.
lim	numeric. A vector of one or multiple breaks.
setdif	logical. If TRUE and length(lim) > 1, nodes that are reachable in a given break will not appear in a greater one.
keep	numeric or character. Vertices of interest that will be returned.
long	logical. If TRUE, a long data.frame is returned instead of a list.

Details

If length(lim) > 1, value is a list of length(from), containing lists of length(lim).

All algorithms are multithreaded. Please use RcppParallel::setThreadOptions() to set the number of threads.

For large graph, keep argument can be used for saving memory.

Value

list or a data.frame containing reachable nodes below cost limit(s).

Note

get_isochrone() recursively perform Dijkstra algorithm for each from nodes and stop when cost limit is reached.

Examples

#Choose number of cores used by cppRouting
RcppParallel::setThreadOptions(numThreads = 1)

#Data describing edges of the graph
edges<-data.frame(from_vertex=c(0,0,1,1,2,2,3,4,4),
                  to_vertex=c(1,3,2,4,4,5,1,3,5),
                  cost=c(9,2,11,3,5,12,4,1,6))

#Construct directed graph
directed_graph<-makegraph(edges,directed=TRUE)

#Get nodes reachable around node 4 with maximum distances of 1 and 2
iso<-get_isochrone(Graph=directed_graph,from = "4",lim=c(1,2))

#With setdif set to TRUE
iso2<-get_isochrone(Graph=directed_graph,from = "4",lim=c(1,2),setdif=TRUE)
print(iso)
print(iso2)

cppRouting documentation built on Dec. 1, 2022, 5:08 p.m.