cograph (version 2.0.0)

layout_spring: Fruchterman-Reingold Spring Layout

Description

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"),
  ...
)

Value

Data frame with x, y coordinates.

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).

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)