# ego

##### Neighborhood of graph vertices

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

- Keywords
- graphs

##### Usage

```
ego(graph, order, nodes = V(graph), mode = c("all", "out", "in"),
mindist = 0)
```make_ego_graph(graph, order, 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 constatnt, 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 ar - 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.

##### Examples

```
g <- make_ring(10)
ego_size(g, 0, 1:3)
ego_size(g, 1, 1:3)
ego_size(g, 2, 1:3)
ego(g, 0, 1:3)
ego(g, 1, 1:3)
ego(g, 2, 1:3)
# attributes are preserved
V(g)$name <- c("a", "b", "c", "d", "e", "f", "g", "h", "i", "j")
make_ego_graph(g, 2, 1:3)
# connecting to the neighborhood
g <- make_ring(10)
g <- connect(g, 2)
```

*Documentation reproduced from package igraph, version 1.0.0, License: GPL (>= 2)*