Draw node elements in a 2D graph layout

Constructor for GeomNodeSpace ggproto objects.

A wrapper around geom_point that enables direct use of node attributes stored in GraphSpace objects as aesthetics.

This geom is designed to map node-level attributes (e.g., fill, size) or any aesthetics supported by GeomPoint.

Usage

geom_nodespace(
  mapping = NULL,
  data = NULL,
  stat = StatNodeSpace,
  position = "identity",
  ...,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = FALSE,
  raster = FALSE,
  dpi = NULL,
  dev = "cairo",
  scale = 1
)

nodespace_handler(mapping = NULL)

Arguments

mapping: Set of aesthetic mappings created by ggplot2::aes(). These mappings override global aesthetics and are not inherited from the top-level plot.
data: The data to be displayed in this layer. It can be a GraphSpace object, an igraph object, or the nodespace_handler() closure. When NULL (default), a handler is created internally from the mapping argument.
stat: The statistical transformation to use on the data. Defaults to identity.
position: Position adjustment, either as a string or the result of a call to a position adjustment function.
...: Additional parameters passed to the underlying drawing function in GeomNodeSpace.
na.rm: Logical. Should missing values be removed? Defaults to FALSE.
show.legend: Logical or a named logical vector indicating whether this layer should be included in legends.
inherit.aes: Logical. If FALSE (default), the layer will use aesthetics defined in mapping.
raster: Logical. Should node glyphs be rasterized? Rasterization support is based on rasterise.
dpi: Numeric. Rasterization resolution.
dev: Character. Rasterization backend. One of 'cairo', 'ragg', 'ragg_png', or 'cairo_png'.
scale: Numeric. Rasterization scaling factor (see rasterise).

Value

A ggplot2 layer that renders node glyphs defined by GeomNodeSpace.

Details

The interpretation of size depends on how it is provided:

As an aesthetic: When mapped within aes(), size follows the behavior of geom_point, using absolute units to ensure consistency with the plot legends.
As a parameter: When set outside aes(), size is treated as a percentage of the viewport ([0, 100]), scaling in npc units. This allows nodes to resize dynamically with viewport changes.

Aesthetics

geom_nodespace() understands geom_point aesthetics.

If these aesthetics are not explicitly provided in aes(), they are automatically retrieved from the GraphSpace object.

`x`, `y`	Node coordinates (required; automatically supplied).
`fill`	Node interior colour (see aes_colour_fill_alpha).
`colour`	Node border colour (see aes_colour_fill_alpha).
`alpha`	Transparency (see aes_colour_fill_alpha).
`shape`	Node shape (see points and aes_linetype_size_shape).
`size`	Node size (see drawing section and aes_linetype_size_shape).
`stroke`	Node line width (see gg_par and aes_linetype_size_shape).

Required aesthetics are supplied from the GraphSpace object and do not need to be manually mapped.

Additional parameters can be passed to control fixed values for the layer. For example: fill = "red", stroke = 3, alpha = 0.5, or shape = 21.

Label aesthetics

When label is mapped via aes(), a text label is drawn at each node's position using geom_text, rendered on top of the node glyph. Nodes with NA labels are silently skipped.

The label_size and label_colour aesthetics are automatically retrieved from the GraphSpace object when not explicitly provided in aes(). All other label_* aesthetics default to geom_text when not set.

`label`	Required to activate label rendering.
`label_size`	Font size (see `geom_text`).
`label_colour`	Label colour (see `geom_text`).
`label_alpha`	Label transparency (see `geom_text`).
`label_angle`	Rotation angle (see `geom_text`).
`label_hjust`	Horizontal justification (see `geom_text`).
`label_vjust`	Vertical justification (see `geom_text`).
`label_family`	Font family (see `geom_text`).
`label_fontface`	Font face (see `geom_text`).
`label_lineheight`	Line height (see `geom_text`).

Examples

library(RGraphSpace)
library(igraph)
library(ggplot2)

# Make a demo igraph
gtoy1 <- make_star(15, mode="out")

# Set some node attributes
V(gtoy1)$nodeSize <- runif(vcount(gtoy1), 1, 20)
V(gtoy1)$nodeColor <- rainbow(vcount(gtoy1))

# Set some variables
V(gtoy1)$user_var1 <- runif(vcount(gtoy1), 1, 3)^3
V(gtoy1)$user_var2 <-  rep(c(1, 2, 3), each = 5)

# Create a GraphSpace object
gs <- GraphSpace(gtoy1, layout = layout_in_circle(gtoy1))
#> Validating the 'igraph' object...
#> Vertex attribute 'name' missing; assigning names... 
#> Ignoring graph-level attributes: 'name', 'mode', 'center'
#> Creating a 'GraphSpace' object...

if (FALSE) { # \dontrun{

# Example 1: Nodes scaling with the legend
# When 'size' is mapped inside aes(), it follows
# ggplot2 default behavior: size is translated 
# to absolute units (mm) via 'scale_size()'.

ggplot(gs) + 
geom_edgespace(arrow_offset = 0.01) +
geom_nodespace(mapping = aes(size = nodeSize, fill = user_var2)) + 
scale_size(range = c(1, 12)) + 
theme(aspect.ratio = 1)
  
# Example 2: Nodes scaling with the viewport
# When 'size' is passed as a node attribute, 
# inherited from the igraph object, it is 
# interpreted as a percentage of the plotting 
# area and translated to NPC units.

ggplot(gs) + 
geom_edgespace(arrow_offset = 0.01) +
geom_nodespace(mapping = aes(fill = user_var2)) +
theme(aspect.ratio = 1)
  
# Example 3: Node labels
ggplot(gs) +
  geom_edgespace() +
  geom_nodespace(aes(label = nodeLabel)) +
  theme(aspect.ratio = 1)
  
} # }