swapEdges: Swap two edges of a supply network

In MiloMonnier/supplynet: Supply network design and robustness assessment tools

Description

Extends rewire used with keeping_degseq with tunable parameters. Possible to force the swap of two edges of different types, or of the same type. Edges swapping can be used to realize a Degree Preserving Randomization (DPR). One of the two edges can be imposed (e1).

Usage

swapEdges(
  g,
  es = E(g),
  e1 = NULL,
  edges.types = c("random", "same", "different"),
  multi.edges = FALSE
)

Arguments

g	An igraph object
es	igraph.es; edge sequence among which to choose edges to swap. (default: all edges).
e1	igraph.es; one of the two swapped edges can be imposed (default: NULL).
edges.types	character string; either 'random', 'same' or 'different': of what type must be edges swapped. Requir E(g)$type attribute (default: 'random').
multi.edges	boolean; whether or not multiple edges creation is allowed (default: FALSE).

Value

An igraph object.

Examples

## Generate a theoretical supply network, define producers (P), intermediaries (I)
## and distributors (D) vertices.
library(igraph)
g = make_tree(10)
V(g)[!degree(g, mode="in")]$type = "P"
V(g)[degree(g, mode="in") & degree(g, mode="out")]$type = "I"
V(g)[!degree(g, mode="out")]$type = "D"
V(g)$color = c("green","red","yellow")[factor(V(g)$type, levels=c("P","I","D"))]
plot(g)
## Swap edges to conserve supply from P to D.
for (i in 1:100) {
 i = ends(g, E(g), names=FALSE)[,1]
 j = ends(g, E(g), names=FALSE)[,2]
 E(g)$type = paste0(V(g)[i]$type, V(g)[j]$type)
 g = swapEdges(g, edges.types="diff")
 if (length(E(g)[which_multiple(g, E(g))]))
    stop("Multiedges")
 if (length(E(g)[which_loop(g, E(g))]))
    stop("Loops")
 if (length(V(g)[degree(g)==0]))
    stop("Isolated vertex")
}
plot(g)

MiloMonnier/supplynet documentation built on Feb. 16, 2021, 8:03 p.m.