Fruchterman-Reingold Spring Layout — layout

Computes node positions with the Fruchterman-Reingold force-directed algorithm. Nodes connected by edges attract each other and all nodes repel each other. Attraction along an edge is scaled by the absolute edge weight. Duplicate edges between the same pair of nodes, in either direction, are merged by summing their weights.

Usage

layout_spring(
  network,
  iterations = 200,
  cooling = 0.95,
  repulsion = 1.5,
  attraction = 1,
  seed = NULL,
  initial = NULL,
  max_displacement = NULL,
  anchor_strength = 0,
  area = 1.5,
  gravity = 0,
  init = c("random", "circular"),
  cooling_mode = c("exponential", "vcf", "linear"),
  ...
)

Arguments

network: A CographNetwork or cograph_network object.
iterations: Number of iterations (default: 200).
cooling: Factor by which the temperature is multiplied after each iteration when cooling_mode = "exponential" (default: 0.95).
repulsion: Repulsion constant (default: 1.5).
attraction: Attraction constant (default: 1).
seed: Random seed for the random initial positions. NULL (default) uses the current random state. When a seed is given, the caller's random state is restored on exit.
initial: Optional initial coordinates, a matrix or a data frame with columns x and y. When supplied, init is ignored. For animations, pass the previous frame's layout to obtain smooth transitions.
max_displacement: Maximum distance a node can move from its initial position (default: NULL, no limit). Applies only when initial is supplied. In that case the coordinates are returned without the final rescaling. Values such as 0.05 to 0.1 suit animations.
anchor_strength: Strength of the force pulling nodes toward their initial positions (default: 0). Higher values (for example 0.5 to 2) keep nodes closer to their starting positions. Applies only when initial is supplied.
area: Area parameter (default: 1.5). It sets the ideal edge length \(k = \sqrt{area / n}\) and the initial temperature \(\sqrt{area} / 10\). Because the final coordinates are rescaled, area changes the relative arrangement of the nodes and leaves the overall extent unchanged.
gravity: Strength of the force pulling nodes toward the centroid of the layout (default: 0). Higher values (for example 0.5 to 2) give a more compact layout.
init: Initialization method, "random" (default) or "circular".
cooling_mode: Cooling schedule. "exponential" (default) multiplies the temperature by cooling after each iteration. "vcf" (variable cooling factor) multiplies it by 0.9 when the mean displacement is below \(0.1k\) and by 0.99 otherwise. "linear" multiplies it by \(1 - t / T\) at iteration \(t\) of \(T\).
...: Additional arguments (ignored).

Value

A data frame with columns x and y and one row per node. The coordinates are centered on their mean and scaled by a common factor into \([0.05, 0.95]\), which preserves the aspect ratio of the layout. A network without edges returns the initial positions, and a single node is placed at (0.5, 0.5).

Examples

layout_spring(CographNetwork$new(regulation_net), seed = 42)
#>            x         y
#> 1  0.7964244 0.5992607
#> 2  0.3632561 0.5210930
#> 3  0.2023914 0.4061824
#> 4  0.7441472 0.3580494
#> 5  0.4212874 0.8198960
#> 6  0.5880101 0.6367377
#> 7  0.6274058 0.9500000
#> 8  0.4826823 0.1498104
#> 9  0.2638862 0.1976380
#> 10 0.5105091 0.3613325