controlling the seed.coord of Fruchterman-Reingold placement does not return identical graphs

layout_par.md

Fruchterman-Reingold placement code by Carter T. Butts. Identical seed coordinates do not return identical network graphs.

layout_par.r

library(network)
library(ggplot2)
library(grid)

# basic random network

x                  <- 10
ndyads             <- x * (x - 1)
density            <- x / ndyads
nw.mat             <- matrix(0, nrow = x, ncol = x)
dimnames(nw.mat)   <- list(1:x, 1:x)
nw.mat[row(nw.mat) != col(nw.mat)] <- runif(ndyads) < density
nw.mat
rnd <- network(nw.mat)
rnd

# create layout coordinates

(n <- network.size(rnd))
tempa <- sample((0:(n - 1))/n)
x <- n/(2 * pi) * sin(2 * pi * tempa)
y <- n/(2 * pi) * cos(2 * pi * tempa)
(tempa <- cbind(x,y))

# requires ggnet with layout.par argument

for(i in 1:4)
  assign(paste0("plot", i), ggnet(rnd, layout.par = list(seed.coord = tempa), label = TRUE, alpha = 1, size = 8, color = "white", segment.color = "grey10"))

vplayout <- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)

grid.newpage()
pushViewport(viewport(layout = grid.layout(2, 2)))
print(plot1, vp = vplayout(1, 1))
print(plot2, vp = vplayout(1, 2))
print(plot3, vp = vplayout(2, 1))
print(plot4, vp = vplayout(2, 2))