Fruchterman-Reingold Spring Layout — layout

Compute node positions using the Fruchterman-Reingold force-directed algorithm. Nodes connected by edges are attracted to each other while all nodes repel each other.

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 object.
iterations: Number of iterations (default: 200).
cooling: Rate of temperature decrease for exponential cooling (default: 0.95).
repulsion: Repulsion constant (default: 1.5).
attraction: Attraction constant (default: 1).
seed: Random seed for reproducibility.
initial: Optional initial coordinates (matrix or data frame). For animations, pass the previous frame's layout to ensure smooth transitions.
max_displacement: Maximum distance a node can move from its initial position (default: NULL = no limit). Useful for animations to prevent large jumps between frames. Values like 0.05-0.1 work well.
anchor_strength: Strength of force pulling nodes toward initial positions (default: 0). Higher values (e.g., 0.5-2) keep nodes closer to their starting positions. Only applies when initial is provided.
area: Area parameter controlling node spread (default: 1.5). Higher values spread nodes further apart.
gravity: Gravity force pulling nodes toward center (default: 0). Higher values (e.g., 0.5-2) prevent nodes from drifting apart.
init: Initialization method: "random" (default) or "circular".
cooling_mode: Cooling schedule: "exponential" (default, uses cooling parameter), "vcf" (Variable Cooling Factor - adapts based on movement), or "linear" (linear decrease over iterations).
...: Additional arguments (ignored).

Value

Data frame with x, y coordinates.

Examples

adj <- matrix(c(0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0), nrow = 4)
net <- CographNetwork$new(adj)
coords <- layout_spring(net, seed = 42)

# For animations: use previous layout as initial with constraints
coords2 <- layout_spring(net, initial = coords, max_displacement = 0.05)

# With gravity to keep nodes centered
coords3 <- layout_spring(net, gravity = 0.5, area = 2, seed = 42)

# With circular initialization and VCF cooling
coords4 <- layout_spring(net, init = "circular", cooling_mode = "vcf", seed = 42)