R: Neighborhood of graph vertices

ego_size {igraph} | R Documentation

## 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)

[Package igraph version 1.2.6 Index]