igraph: ego – R documentation

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ego

Neighborhood of graph vertices

Description

These functions find the vertices not farther than a given limit from another fixed vertex, these are called the neighborhood of the vertex.

Usage

ego_size(
  graph,
  order = 1,
  nodes = V(graph),
  mode = c("all", "out", "in"),
  mindist = 0
)

ego(
  graph,
  order = 1,
  nodes = V(graph),
  mode = c("all", "out", "in"),
  mindist = 0
)

make_ego_graph(
  graph,
  order = 1,
  nodes = V(graph),
  mode = c("all", "out", "in"),
  mindist = 0
)

Arguments

`graph`	The input graph.
`order`	Integer giving the order of the neighborhood.
`nodes`	The vertices for which the calculation is performed.
`mode`	Character constant, it specifies how to use the direction of the edges if a directed graph is analyzed. For ‘out’ only the outgoing edges are followed, so all vertices reachable from the source vertex in at most `order` steps are counted. For ‘"in"’ all vertices from which the source vertex is reachable in at most `order` steps are counted. ‘"all"’ ignores the direction of the edges. This argument is ignored for undirected graphs.
`mindist`	The minimum distance to include the vertex in the result.

Details

The neighborhood of a given order o of a vertex v includes all vertices which are closer to v than the order. Ie. order 0 is always v itself, order 1 is v plus its immediate neighbors, order 2 is order 1 plus the immediate neighbors of the vertices in order 1, etc.

ego_size calculates the size of the neighborhoods for the given vertices with the given order.

ego calculates the neighborhoods of the given vertices with the given order parameter.

make_ego_graph is creates (sub)graphs from all neighborhoods of the given vertices with the given order parameter. This function preserves the vertex, edge and graph attributes.

connect creates a new graph by connecting each vertex to all other vertices in its neighborhood.

Value

ego_size returns with an integer vector.

ego returns with a list of integer vectors.

make_ego_graph returns with a list of graphs.

connect returns with a new graph object.

Author(s)

Gabor Csardi csardi.gabor@gmail.com, the first version was done by Vincent Matossian

Examples

g <- make_ring(10)
ego_size(g, order = 0, 1:3)
ego_size(g, order = 1, 1:3)
ego_size(g, order = 2, 1:3)
ego(g, order = 0, 1:3)
ego(g, order = 1, 1:3)
ego(g, order = 2, 1:3)

# attributes are preserved
V(g)$name <- c("a", "b", "c", "d", "e", "f", "g", "h", "i", "j")
make_ego_graph(g, order = 2, 1:3)

# connecting to the neighborhood
g <- make_ring(10)
g <- connect(g, 2)

igraph

Network Analysis and Visualization

v1.2.10

GPL (>= 2)

Authors

See AUTHORS file.

Initial release

ego