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Calculate ego-centric layout positions for network visualization

Source: R/get_ego_layout.R
get_ego_layout.Rd

get_ego_layout computes node positions for ego network visualization using ego-centric layout algorithms. These layouts place the ego at the center and arrange alters in meaningful patterns around it, making the ego's relationships more visually apparent.

Usage

get_ego_layout(
  netlet,
  layout = "star",
  group_by = NULL,
  order_by = NULL,
  weight_to_distance = FALSE,
  ring_gap = 0.3,
  ego_size = 0.1,
  seed = 6886
)

Arguments

netlet

A netify object (class "netify") that is an ego network, created using ego_netify. The object must have ego_netify = TRUE attribute.

layout

Character string specifying the ego-centric layout algorithm. Options:

  • "radial": Places ego at center with alters arranged in a circle around it. Distance from center can encode relationship strength.

  • "concentric": Places ego at center with alters in concentric circles based on a grouping variable or relationship strength.

  • "star": Simple star layout with ego at center and alters equally spaced around it (default).

group_by

Character string specifying a nodal attribute to use for grouping alters in the layout. For "radial" layout, groups are arranged in sectors. For "concentric" layout, groups determine which ring alters appear in. If NULL (default), no grouping is applied.

order_by

Character string specifying a nodal attribute to use for ordering alters within their groups or around the ego. Common options include network statistics like "degree_total" or custom attributes. If NULL (default), alters are arranged alphabetically.

weight_to_distance

Logical. If TRUE and the network is weighted, use edge weights to determine distance from ego (higher weights = closer). For "radial" layout only. Default is FALSE.

ring_gap

Numeric value between 0 and 1 specifying the gap between concentric rings as a proportion of the total radius. Only used for "concentric" layout. Default is 0.3.

ego_size

Numeric value specifying the relative size of the central area reserved for the ego. Larger values create more space between ego and alters. Default is 0.1.

seed

Integer for random number generation to ensure reproducible layouts when there are ties in ordering. Default is 6886.

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 provides specialized layouts for ego networks that emphasize the ego-alter structure:

Layout algorithms:

  • Radial: Places the ego at the origin and arranges alters in a circle around it. If grouping is specified, alters are arranged in sectors with related nodes near each other. If weight_to_distance is TRUE, alters with stronger ties to ego are placed closer to the center.

  • Concentric: Places the ego at the origin and arranges alters in concentric circles. The ring assignment can be based on a grouping variable (categorical) or a continuous variable (discretized into rings).

  • Star: A simple star layout that places ego at center and distributes alters evenly around a single circle. This is equivalent to the radial layout without grouping or weighting.

Visual encoding:

The layouts allow encoding of network properties through spatial arrangement:

  • Distance from ego: Can represent tie strength, frequency of interaction, or other dyadic measures

  • Angular position: Can group similar alters together (e.g., family, friends, colleagues)

  • Ring assignment: Can represent categories, levels of importance, or discretized continuous variables

Longitudinal networks:

For longitudinal ego networks, the function maintains consistent angular positions for alters across time periods when possible, making it easier to track changes in the ego's network over time.

Note

This function is designed specifically for ego networks created with ego_netify. For general network layouts, use get_node_layout.

The function will issue a warning if used on non-ego networks but will attempt to proceed by treating the first node as the ego.

Author

Cassy Dorff, Shahryar Minhas

Examples

if (FALSE) { # \dontrun{
# Create an ego network
ego_net <- ego_netify(my_network, ego = "Alice")

# Get radial layout with alters grouped by attribute
layout_radial <- get_ego_layout(ego_net, 
                               layout = "radial",
                               group_by = "department")

# Get concentric layout with rings based on degree
layout_circles <- get_ego_layout(ego_net,
                                layout = "concentric", 
                                group_by = "degree_total")

# Use with plot
plot(ego_net, point_layout = layout_radial)
} # }