Apply colors based on edge attribute values — colorize_edge

Within a graph's internal edge data frame (edf), use a categorical edge attribute to generate a new edge attribute with color values.

colorize_edge_attrs(
  graph,
  edge_attr_from,
  edge_attr_to,
  cut_points = NULL,
  palette = "Spectral",
  alpha = NULL,
  reverse_palette = FALSE,
  default_color = "#D9D9D9"
)

Arguments

graph: A graph object of class dgr_graph.
edge_attr_from: The name of the edge attribute column from which color values will be based.
edge_attr_to: The name of the new edge attribute to which the color values will be applied.
cut_points: An optional vector of numerical breaks for bucketizing continuous numerical values available in a edge attribute column.
palette: Can either be: (1) a palette name from the RColorBrewer package (e.g., Greens, OrRd, RdYlGn), (2) viridis, which indicates use of the viridis color scale from the package of the same name, or (3) a vector of hexadecimal color names.
alpha: An optional alpha transparency value to apply to the generated colors. Should be in the range of 0 (completely transparent) to 100 (completely opaque).
reverse_palette: An option to reverse the order of colors in the chosen palette. The default is FALSE.
default_color: A hexadecimal color value to use for instances when the values do not fall into the bucket ranges specified in the cut_points vector.

Value

A graph object of class dgr_graph.

Examples

# Create a graph with 5
# nodes and 4 edges
graph <-
  create_graph() %>%
  add_path(n = 5) %>%
  set_edge_attrs(
    edge_attr = weight,
    values = c(3.7, 6.3, 9.2, 1.6))

# We can bucketize values in
# the edge `weight` attribute using
# `cut_points` and, by doing so,
# assign colors to each of the
# bucketed ranges (for values not
# part of any bucket, a gray color
# is assigned by default)
graph <-
  graph %>%
  colorize_edge_attrs(
    edge_attr_from = weight,
    edge_attr_to = color,
    cut_points = c(0, 2, 4, 6, 8, 10),
    palette = "RdYlGn")

# Now there will be a `color`
# edge attribute with distinct
# colors (from the RColorBrewer
# Red-Yellow-Green palette)
graph %>% get_edge_df()
#>   id from to  rel weight   color
#> 1  1    1  2 <NA>    3.7 #FDAE61
#> 2  2    2  3 <NA>    6.3 #A6D96A
#> 3  3    3  4 <NA>    9.2 #1A9641
#> 4  4    4  5 <NA>    1.6 #D7191C