# is_graphical

##### Is a degree sequence graphical?

Determine whether the given vertex degrees (in- and out-degrees for directed graphs) can be reliazed in a simple graph, i.e. a graph without multiple or loop edges.

- Keywords
- graphs

##### Usage

`is_graphical(out.deg, in.deg = NULL)`

##### Arguments

- out.deg
Integer vector, the degree sequence for undirected graphs, or the out-degree sequence for directed graphs.

- in.deg
`NULL`

or an integer vector. For undireted graphs, it should be`NULL`

. For directed graphs it specifies the in-degrees.

##### Value

A logical scalar.

##### References

Hakimi SL: On the realizability of a set of integers as degrees
of the vertices of a simple graph. *J SIAM Appl Math* 10:496-506, 1962.

PL Erdos, I Miklos and Z Toroczkai: A simple Havel-Hakimi type algorithm to
realize graphical degree sequences of directed graphs. *The Electronic
Journal of Combinatorics* 17(1):R66, 2010.

##### See Also

Other graphical degree sequences

g <- sample_gnp(100, 2/100)
is_degseq(degree(g))
is_graphical(degree(g)): `is.degree.sequence`

,
`is_degseq`

*Documentation reproduced from package igraph, version 1.0.1, License: GPL (>= 2)*