Introduction
library(netplot)
library(igraph)
library(sna)
library(ggraph)
# We will use the UKfaculty data from the igraphdata package
data("UKfaculty", package = "igraphdata")
# With a fixed layout
set.seed(225)
l_ukf <- layout_with_fr(UKfaculty)
Since igraph and statnet do the plotting using base system graphics,
we can’t put everything in the same device right away. Fortunately, the
gridGraphics R package allows us to reproduce base graphics
using the grid system, which, in combination with the
function gridExtra::grid.arrange will let us put both base
and grid graphics in the same page. First me write a func
# Function to map base to grid
map_base_to_grid <- function(fun) {
gridGraphics::grid.echo(fun)
grid::grid.grab()
}
# Mapping base to grid
ig <- map_base_to_grid(function() plot(UKfaculty, main = "igraph"))
nw <- map_base_to_grid(function() gplot(as.matrix(as_adj(UKfaculty)), coord = l_ukf, main = "sna"))
#> Warning: `as_adj()` was deprecated in igraph 2.1.0.
#> ℹ Please use `as_adjacency_matrix()` instead.
#> This warning is displayed once per session.
#> Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
#> generated.
nplot(UKfaculty, layout = l_ukf)
grid::grid.text("netplot", x = .05, y=.9)
np <- grid::grid.grab()
Here is an example with ggraph
ggraph::ggraph(UKfaculty, layout = l_ukf) +
ggraph::geom_edge_arc() +
ggraph::geom_node_point() +
ggplot2::ggtitle("ggraph")
gg <- grid::grid.grab()
# Putting all together
gridExtra::grid.arrange(ig, nw, gg, np, nrow=2, ncol=2)
Comparison of default igraph,
sna, ggraph, and netplot default
call. nplot fills completely the plotting area, and adjusts
vertex size, edge width, and edge arrows’ size accordingly to the
plotting area and plotting device.
Multiple plots
To arrange multiple plots in the same page we can use the
grid.arrange function from the gridExtra
package
x_igraph <- sample_smallworld(1, 20, 4, .05)
x_network <- intergraph::asNetwork(x_igraph)
l <- layout_nicely(x_igraph)
# Putting two plots in the same page (one using igraph and the other network)
gridExtra::grid.arrange(
nplot(x_igraph, layout = l),
nplot(x_network, layout = l), ncol=2, nrow=1
)
Nodes
gridExtra::grid.arrange(
nplot(UKfaculty, layout = l_ukf,
vertex.size = rep(.025, vcount(UKfaculty)),
vertex.size.range = NULL),
nplot(UKfaculty, layout = l_ukf, vertex.size.range = c(.01, .025)),
nplot(UKfaculty, layout = l_ukf, vertex.size.range = c(.01, .025, 4)),
nplot(UKfaculty, layout = l_ukf, vertex.size.range = c(.02, .05, 4)),
ncol=2, nrow=2
)
Modifying vertex.size.range: use
NULL to keep the supplied vertex sizes unchanged.
nplot(make_ring(5), vertex.nsides = 2:6,
vertex.size.range = c(.1,.1),
edge.curvature = 0)
Number of sides for node drawing.
Edges
set.seed(12233)
x <- sample_smallworld(1, size = 10, nei = 2, .1)
l <- layout_with_fr(x)
gridExtra::grid.arrange(
nplot(
x, layout = l,
edge.color = ~ego(mix=0, alpha = .1, col="black") + alter(mix=1),
vertex.size.range = c(.05,.1)
),
nplot(
x, layout = l,
edge.color = ~ego(mix=.5, alpha = .1, col="black") + alter(mix=.5),
vertex.size.range = c(.05,.1)
),
nplot(
x, layout = l,
edge.color = ~ego(mix=1, alpha = .1, col="black") + alter(mix=0),
vertex.size.range = c(.05,.1)
),
ncol=3, nrow=1
)
Modifying edge.color.mix: Each
figure shows a different parameter for the edge color mixer. From left
to right, (a) colors the edges as alter, (b) mixes ego and alter’s
colors, and (c) only uses ego
gridExtra::grid.arrange(
nplot(x, layout = l, edge.curvature = 0, vertex.size.range = c(.05,.1)),
nplot(x, layout = l, edge.curvature = pi/2, vertex.size.range = c(.05,.1)),
nplot(x, layout = l, edge.curvature = pi, vertex.size.range = c(.05,.1)),
ncol = 3, nrow=1
)
Modifying edge.curvature: Each
figure shows a different parameter for the edge curvature. From left to
right, (a) straight edges, (b) the edge between ego and alter is an arc
that measures \(\pi/2\) radians (90
degree), and (c) the edge as an arc between ego and alter that measures
\(\pi\) radians (180 degrees).
gridExtra::grid.arrange(
nplot(x, layout = l, edge.line.breaks=3),
nplot(x, layout = l, edge.line.lty = 2, edge.line.breaks=10),
nplot(x, layout = l, edge.line.lty = 3, edge.line.breaks=10),
nplot(x, layout = l, edge.line.lty = 4, edge.line.breaks=10),
nrow=2, ncol=2
)
Changing the number of breaks in the edge (arc)
and the type of line to be drawn.
Edge width
The edge.width parameter controls the relative width of
each edge. Values are normalized and mapped to the range
[min, max] specified by edge.width.range (in
points). For nplot.igraph, this defaults to the
"weight" edge attribute when present. Use
edge.width.range = NULL to keep supplied widths
unchanged.
set.seed(1)
x_w <- make_ring(8)
# Assign varying edge weights
E(x_w)$weight <- c(1, 3, 1, 5, 2, 4, 1, 6)
l_w <- layout_in_circle(x_w)
gridExtra::grid.arrange(
nplot(x_w, layout = l_w, skip.arrows = TRUE,
vertex.size.range = c(.05, .05),
edge.width = 1,
edge.width.range = c(1, 2)),
nplot(x_w, layout = l_w, skip.arrows = TRUE,
vertex.size.range = c(.05, .05),
edge.width = E(x_w)$weight,
edge.width.range = c(1, 2)),
nplot(x_w, layout = l_w, skip.arrows = TRUE,
vertex.size.range = c(.05, .05),
edge.width = E(x_w)$weight,
edge.width.range = NULL),
ncol = 3, nrow = 1
)
Effect of edge.width and
edge.width.range. Left: uniform width. Middle: weights
mapped to 1–2 pt. Right: raw weights with
edge.width.range = NULL.
You can also modify edge widths after the plot has been created using
set_edge_gpar():
g <- nplot(x_w, layout = l_w, skip.arrows = TRUE,
vertex.size.range = c(.05, .05))
gridExtra::grid.arrange(
set_edge_gpar(g, element = "line", lwd = 1),
set_edge_gpar(g, element = "line", lwd = 4),
ncol = 2
)
Using set_edge_gpar() to change
edge widths after plotting. Left: all edges set to 1 pt. Right: all
edges set to 4 pt.