is_degseq
checks whether the given vertex degrees (in- and
out-degrees for directed graphs) can be realized by a graph. Note that the
graph does not have to be simple, it may contain loop and multiple edges.
For undirected graphs, it also checks whether the sum of degrees is even.
For directed graphs, the function checks whether the lengths of the two
degree vectors are equal and whether their sums are also equal. These are
known sufficient and necessary conditions for a degree sequence to be valid.is_degseq(out.deg, in.deg = NULL)
NULL
or an integer vector. For undireted graphs, it
should be NULL
. For directed graphs it specifies the in-degrees.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.
g <- sample_gnp(100, 2/100)
is_degseq(degree(g))
is_graphical(degree(g)): is.graphical.degree.sequence
,
is_graphical