geom_nodespace: Draw node elements in a 2D graph layout

In RGraphSpace: A Lightweight Interface Between 'igraph' and 'ggplot2' Graphics

Draw node elements in a 2D graph layout

Description

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).

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.

Value

A ggplot2 layer that renders node glyphs defined by GeomNodeSpace.

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	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 x and y 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.

Integration with ggraph

geom_nodespace is compatible with the ggraph methods. When used within a ggraph() call, the default nodespace_handler() automatically:

• Identifies the current layout_ggraph.

• Extracts the x and y coordinates calculated by ggraph.

• Reconstructs a temporary GraphSpace object to inject spatial metadata and user-chosen ggraph layout.

See Also

GraphSpace, geom_edgespace, geom_graphspace, geom_point

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))

## Not run: 

# 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() + 
geom_edgespace(data = gs, arrow_offset = 0.01) +
  geom_nodespace(mapping = aes(size = nodeSize, fill = user_var2), 
  data = gs) + 
  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() + 
geom_edgespace(data = gs, arrow_offset = 0.01) +
geom_nodespace(mapping = aes(fill = user_var2), data = gs) +
theme(aspect.ratio = 1)
  

## End(Not run)

RGraphSpace documentation built on June 13, 2026, 9:06 a.m.