Edge colour / alpha / line-type scales

Declare the scale for a mapped edge aesthetic on a vgraph() plot – the colour (mark_edges(color = )), opacity (alpha = ), or line type (linetype = ) of the edges. These are the edge counterparts of scale_color_continuous() / scale_alpha() / scale_linetype(): an edge aesthetic is trained and legended independently of the node scales, so a figure can map, say, node fill to a discrete community and edge colour to a continuous weight without the two collapsing into one legend. Each draws its own legend automatically.

Usage

scale_edge_color(
  plot,
  palette = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL,
  midpoint = NULL
)

scale_edge_colour(
  plot,
  palette = NULL,
  breaks = NULL,
  labels = NULL,
  name = NULL,
  midpoint = NULL
)

scale_edge_alpha(plot, range = NULL, limits = NULL, breaks = NULL, name = NULL)

scale_edge_linetype(plot, values = NULL, name = NULL)

Arguments

plot

A PlotSpec, normally from vgraph().

palette

For scale_edge_color(), a vector of colours or a single palette name (as in scale_color_continuous()); NULL for a default.

name

Legend title, or NULL to derive from the encoding.

midpoint

For scale_edge_color(), the data value placed at the ramp's midpoint (a diverging scale); NULL for an ordinary ramp.

range

For scale_edge_alpha(), the output opacity range c(min, max), or NULL for the default.

limits, breaks, labels

Data limits, explicit legend breaks, and explicit labels, or NULL to derive from the data.

values

For scale_edge_linetype(), a character vector of line types (as in scale_linetype()); NULL for the default palette.

Value

The modified PlotSpec.

Details

scale_edge_color() infers discrete vs continuous from the mapped data (a factor/character trains a discrete swatch legend; a number a colour bar), the same as the node colour scale. scale_edge_colour() is a British-spelling alias.

See also

mark_edges(), scale_edge_width(), vgraph()

Examples

if (FALSE) { # \dontrun{
g <- igraph::make_graph("Zachary")
g <- igraph::set_edge_attr(g, "w", value = runif(igraph::ecount(g)))
vgraph(g) |>
  mark_edges(color = w) |>
  mark_nodes(fill = factor(igraph::membership(igraph::cluster_louvain(g)))) |>
  scale_edge_color(palette = "Grays")
} # }