estimate_centrality_time: estimate_centrality_time

Description Usage Arguments Value Note

Description

The 'dodgr' centrality functions are designed to be applied to potentially very large graphs, and may take considerable time to execute. This helper function estimates how long a centrality function may take for a given graph and given value of 'dist_threshold' estimated via the estimate_centrality_threshold function.

Usage

1
2
3
4
5
6
7
estimate_centrality_time(
  graph,
  contract = TRUE,
  edges = TRUE,
  dist_threshold = NULL,
  heap = "BHeap"
)

Arguments

graph

'data.frame' or equivalent object representing the network graph (see Details)

contract

If 'TRUE', centrality is calculated on contracted graph before mapping back on to the original full graph. Note that for street networks, in particular those obtained from the osmdata package, vertex placement is effectively arbitrary except at junctions; centrality for such graphs should only be calculated between the latter points, and thus 'contract' should always be 'TRUE'.

edges

If 'TRUE', centrality is calculated for graph edges, returning the input 'graph' with an additional 'centrality' column; otherwise centrality is calculated for vertices, returning the equivalent of 'dodgr_vertices(graph)', with an additional vertex-based 'centrality' column.

dist_threshold

If not 'NULL', only calculate centrality for each point out to specified threshold. Setting values for this will result in approximate estimates for centrality, yet with considerable gains in computational efficiency. For sufficiently large values, approximations will be accurate to within some constant multiplier. Appropriate values can be established via the estimate_centrality_threshold function.

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

An estimated calculation time for calculating centrality for the given value of 'dist_threshold'

Note

This function may take some time to execute. While running, it displays ongoing information on screen of estimated values of 'dist_threshold' and associated errors. Thresholds are progressively increased until the error is reduced below the specified tolerance.


dodgr documentation built on Aug. 8, 2021, 1:06 a.m.