R igraph manual pages

Simple graphs

Description

Simple graphs are graphs which do not contain loop and multiple edges.

Usage

simplify(
  graph,
  remove.multiple = TRUE,
  remove.loops = TRUE,
  edge.attr.comb = igraph_opt("edge.attr.comb")
)

is_simple(graph)

Arguments

graph	The graph to work on.
remove.multiple	Logical, whether the multiple edges are to be removed.
remove.loops	Logical, whether the loop edges are to be removed.
edge.attr.comb	Specifies what to do with edge attributes, if remove.multiple=TRUE. In this case many edges might be mapped to a single one in the new graph, and their attributes are combined. Please see attribute.combination for details on this.

Details

A loop edge is an edge for which the two endpoints are the same vertex. Two edges are multiple edges if they have exactly the same two endpoints (for directed graphs order does matter). A graph is simple is it does not contain loop edges and multiple edges.

is_simple checks whether a graph is simple.

simplify removes the loop and/or multiple edges from a graph. If both remove.loops and remove.multiple are TRUE the function returns a simple graph.

Value

A new graph object with the edges deleted.

Author(s)

Gabor Csardi csardi.gabor@gmail.com

See Also

which_loop, which_multiple and count_multiple, delete_edges, delete_vertices

Examples

g <- graph( c(1,2,1,2,3,3) )
is_simple(g)
is_simple(simplify(g, remove.loops=FALSE))
is_simple(simplify(g, remove.multiple=FALSE))
is_simple(simplify(g))

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