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Network (graph) marks

Source: R/marks.R
mark_graph.Rd

Draw a node-link diagram on a PlotSpec from vgraph(). mark_edges() draws the edges (straight lines, batched), mark_nodes() the vertices (points), and mark_node_text() the vertex labels. Draw order is fixed regardless of the order you pipe them: edges under nodes under labels. Edges default to the edge table (vgraph()'s edge_data), nodes and labels to the node table; the x/y/xend/yend/label/name columns those tables carry are mapped automatically, so bare mark_edges() |> mark_nodes() just works.

Usage

mark_edges(
  plot,
  ...,
  color = NULL,
  linewidth = NULL,
  alpha = NULL,
  arrow = FALSE,
  blend = NULL,
  effects = list(),
  sketch = NULL,
  data = NULL
)

mark_nodes(
  plot,
  ...,
  size = NULL,
  shape = NULL,
  fill = NULL,
  color = NULL,
  alpha = NULL,
  blend = NULL,
  effects = list(),
  sketch = NULL,
  data = NULL
)

mark_node_text(
  plot,
  ...,
  label = NULL,
  color = NULL,
  size = NULL,
  alpha = NULL,
  blend = NULL,
  data = NULL
)

Arguments

plot

A PlotSpec, normally from vgraph().

...

Encodings mapping node/edge attributes to aesthetics. Nodes: size, color/fill, shape, alpha. Edges: color, linewidth, alpha. The position channels are supplied by vgraph() and need not be mapped.

linewidth

For mark_edges(), the edge width; a constant or (via scale_edge_width()) a mapped expression such as linewidth = weight.

arrow

For mark_edges(), TRUE to draw an arrowhead at each edge's target end (directed graphs). Edges are capped exactly at each endpoint's node boundary (per vertex, at any size/resolution), so the head sits on the node edge; self-loops are drawn as teardrop loops sized to the node, with the head on the node boundary.

blend

Optional blend mode (see mark_point()).

effects

A list of layer render effects (glow(), outline(), shadow()) applied to the mark at draw time.

sketch

A sketch() spec giving the layer a hand-drawn look, NA/FALSE to force it crisp, or NULL (default) to inherit.

data

Optional layer data; overrides the default table.

size, shape

For mark_nodes(), the node size (mm) / shape; a constant or a mapped expression.

fill, color, alpha

Convenience aesthetics; a constant or a mapped expression. For nodes, fill (or color) is the marker colour.

label

For mark_node_text(), the label expression (default the vertex name).

Value

The modified PlotSpec.

Details

These are thin over the point / segment / text marks; igraph need not be installed to use them (only vgraph() needs it).

See also

vgraph(), scale_edge_width()

Examples

if (FALSE) { # \dontrun{
g <- igraph::make_graph("Zachary")
vgraph(g) |>
  mark_edges(alpha = 0.5) |>
  mark_nodes(size = 4, fill = "steelblue")
} # }