Edge direction guide — guide_edge

This guide is intended to show the direction of edges based on the aesthetics mapped to its progression, such as changing width, colour and opacity.

guide_edge_direction(
  title = NULL,
  theme = NULL,
  arrow = NULL,
  labels = NULL,
  nbin = 500,
  position = NULL,
  direction = NULL,
  reverse = FALSE,
  order = 0,
  override.aes = list(),
  ...,
  available_aes = c("edge_colour", "edge_alpha", "edge_width"),
  arrow.position = deprecated()
)

Arguments

title: A character string or expression indicating a title of guide. If NULL, the title is not shown. By default (waiver()), the name of the scale object or the name specified in labs() is used for the title.
theme: A theme object to style the guide individually or differently from the plot's theme settings. The theme argument in the guide overrides, and is combined with, the plot's theme.
arrow: Logical. Should an arrow be drawn to illustrate the direction. Defaults to TRUE. The arrow is styled with the legend.axis.line theme element. If FALSE the direction will be indicated by the text given in labels
labels: A vector with two strings giving the labels to place at the start and the end of the legend to indicate direction if arrow = FALSE
nbin: A numeric specifying the number of bins for drawing the colourbar. A smoother colourbar results from a larger value.
position: A character string indicating where the legend should be placed relative to the plot panels.
direction: A character string indicating the direction of the guide. One of "horizontal" or "vertical."
reverse: logical. If TRUE the colourbar is reversed. By default, the highest value is on the top and the lowest value is on the bottom
order: positive integer less than 99 that specifies the order of this guide among multiple guides. This controls the order in which multiple guides are displayed, not the contents of the guide itself. If 0 (default), the order is determined by a secret algorithm.
override.aes: A list specifying aesthetic parameters of legend key. See details and examples.
...: ignored.
available_aes: A vector of character strings listing the aesthetics for which a colourbar can be drawn.
arrow.position: The position of the arrow relative to the example edge. Use the legend.text.position argument in theme() instead.

Examples

gr <- tidygraph::as_tbl_graph(highschool)
ggraph(gr, layout = 'kk') +
  geom_edge_fan(aes(alpha = after_stat(index))) +
  guides(edge_alpha = guide_edge_direction())


# Use text labels instead of an arrow
ggraph(gr, layout = 'kk') +
  geom_edge_fan(aes(alpha = after_stat(index))) +
  guides(edge_alpha = guide_edge_direction(labels = c('start', 'end')))


# Style the indicator arrow
arrow_style <- element_line(linewidth = 3, arrow = grid::arrow(type = "closed"))
ggraph(gr, layout = 'kk') +
  geom_edge_fan(aes(alpha = after_stat(index))) +
  guides(
    edge_alpha = guide_edge_direction(
      theme = theme(legend.axis.line = arrow_style)
    )
  )