create: Make networks with defined structures

Description

These functions create networks with particular structural properties. They can create either one-mode or two-mode networks. To create a one-mode network, pass the main argument n a single integer, indicating the number of nodes in the network. To create a two-mode network, pass n a vector of two integers, where the first integer indicates the number of nodes in the first mode, and the second integer indicates the number of nodes in the second mode. As an alternative, an existing network can be provided to n and the number of modes and nodes will be inferred.

By default, all networks are created as undirected. This can be overruled with the argument directed = TRUE. This will return a directed network in which the arcs are out-facing or equivalent. This direction can be swapped using to_redirected(). In two-mode networks, this is ignored.

Usage

create_empty(n)
create_complete(n, directed = FALSE)
create_ring(n, width = 1, directed = FALSE, ...)
create_star(n, directed = FALSE)
create_tree(n, directed = FALSE, width = 2)
create_lattice(n, directed = FALSE)
create_components(n, membership = NULL)
create_core(n, membership = NULL)

Value

By default an igraph object is returned, but this can be coerced into other types of objects using as_edgelist(), as_matrix(), as_tidygraph(), or as_network().

Arguments

n

Given:

A single integer, e.g. n = 10, a one-mode network will be created.
A vector of two integers, e.g. n = c(5,10), a two-mode network will be created.
A migraph-compatible object, a network of the same dimensions will be created.

directed

Logical whether the graph should be directed. By default directed = FALSE. If the opposite direction is desired, use to_redirected().

width

Integer specifying the width or breadth of the ring or branches.

...

Additional arguments passed on to {igraph}.

membership

A vector of partition membership as integers. If left as NULL (the default), nodes in each mode will be assigned to two, equally sized partitions.

Functions

create_empty(): Creates an empty graph of the given dimensions.
create_complete(): Creates a filled graph of the given dimensions, with every possible tie realised.
create_ring(): Creates a ring or chord graph of the given dimensions that loops around is of a certain width or thickness.
create_star(): Creates a graph of the given dimensions that has a maximally central node
create_tree(): Creates a graph of the given dimensions with successive branches.
create_lattice(): Creates a graph of the given dimensions with ties to all neighbouring nodes
create_components(): Creates a graph in which the nodes are clustered into separate components.
create_core(): Creates a graph with a certain proportion of nodes being core nodes, densely tied to each other and peripheral nodes, and the rest peripheral, tied only to the core.

Examples

Run this code

autographr(create_empty(10)) + autographr(create_complete(10))
autographr(create_empty(c(8,6))) + autographr(create_complete(c(8,6)))
autographr(create_ring(8, width = 2)) +
autographr(create_ring(c(8,6), width = 2))
autographr(create_star(12)) +
autographr(create_star(12, directed = TRUE)) +
autographr(create_star(c(12,1)))
autographr(create_tree(c(7,8), directed = TRUE)) +
autographr(create_tree(15, directed = TRUE), "tree") +
autographr(create_tree(15, directed = TRUE, width = 3), "tree")
autographr(create_lattice(5), layout = "kk") +
autographr(create_lattice(c(5,5))) +
autographr(create_lattice(c(5,5,5)))
autographr(create_components(10, membership = c(1,1,1,2,2,2,3,3,3,3)))
autographr(create_components(c(10, 12)))
autographr(create_core(6)) +
autographr(create_core(6, membership = c(1,1,1,1,2,2))) +
autographr(create_core(c(6,6)))