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Calculate node layout positions for netify visualization

Source: R/get_node_layout.R
get_node_layout.Rd

get_node_layout computes node positions for network visualization using various layout algorithms from igraph. This function converts a netify object to igraph format, applies the specified layout algorithm, and returns node coordinates suitable for plotting.

Usage

get_node_layout(
  netlet,
  layout = NULL,
  static_actor_positions = FALSE,
  which_static = NULL,
  seed = 6886,
  ig_netlet = NULL,
  ...
)

Arguments

netlet

A netify object (class "netify") for which to compute layout positions.

layout

Character string specifying the layout algorithm to use. Options include:

  • "nicely": Automatic selection of appropriate layout (default for unipartite)

  • "bipartite": Two-column layout for bipartite networks (default for bipartite)

  • "fruchtermanreingold" or "fr": Force-directed layout

  • "kamadakawai" or "kk": Another force-directed layout

  • "circle": Nodes arranged in a circle

  • "star": Star-shaped layout

  • "grid": Nodes on a grid

  • "tree": Hierarchical tree layout

  • "random" or "randomly": Random positions

  • Additional options: "graphopt", "sugiyama", "drl", "lgl", "dh", "gem", "mds"

If NULL, defaults to "nicely" for unipartite or "bipartite" for bipartite networks.

static_actor_positions

Logical. If TRUE, maintains consistent node positions across all time periods in longitudinal networks. If FALSE (default), each time period gets its own optimized layout.

which_static

Integer specifying which time period's layout to use as the static template when static_actor_positions is TRUE. If NULL (default), creates a static layout based on the union of all edges across time periods, giving more weight to persistent edges.

seed

Integer for random number generation to ensure reproducible layouts. Default is 6886.

ig_netlet

An optional pre-converted igraph object. If provided, this function will use it directly instead of converting the netify object again.

...

Additional arguments passed to ego-specific layout functions when layout is "radial" or "concentric". See get_ego_layout for available options (ego_group_by, ego_order_by, ego_weight_to_distance, etc.).

Value

A list of data frames (one per time period) where each data frame contains:

  • index: Integer node index

  • actor: Character string with actor name

  • x: Numeric x-coordinate for node position

  • y: Numeric y-coordinate for node position

For cross-sectional networks, returns a list with one element. For longitudinal networks, returns a named list with time periods as names.

Details

This function handles layout generation for both cross-sectional and longitudinal networks with several key features:

Layout algorithms:

The function provides access to all major igraph layout algorithms. The default "nicely" option automatically selects an appropriate algorithm based on the network structure. For ego networks, specialized layouts ("radial" and "concentric") are available that emphasize the ego-alter structure.

Longitudinal layouts:

For longitudinal networks, two approaches are available:

  • Dynamic layouts: Each time period gets its own optimized layout, which may better reveal structural changes but makes visual comparison harder

  • Static layouts: All time periods use the same node positions, facilitating visual comparison of network evolution

When using static layouts with which_static = NULL, the function creates a composite layout based on the union of all edges across time periods. Edges that appear more frequently are given higher weight, producing layouts that emphasize the stable core structure of the network.

Bipartite networks:

For bipartite networks, the default layout arranges the two node sets in separate columns.

Author

Cassy Dorff, Shahryar Minhas