igraph (version 0.7.1)

as.directed: Convert between directed and undirected graphs

Description

as.directed converts an undirected graph to directed, as.undirected does the opposite, it converts a directed graph to undirected.

Usage

as.directed(graph, mode = c("mutual", "arbitrary")) 
as.undirected(graph, mode = c("collapse", "each", "mutual"),
       edge.attr.comb = getIgraphOpt("edge.attr.comb"))

Arguments

graph

The graph to convert.

mode

Character constant, defines the conversion algorithm. For as.directed it can be mutual or arbitrary. For as.undirected it can be each, collapse or mutual

edge.attr.comb

Specifies what to do with edge attributes, if mode="collapse" or mode="mutual". In these cases many edges might be mapped to a single one in the new graph, and their attributes are combined. Please see

Value

• A new graph object.

concept

• Directed graph
• Undirected graph

Details

Conversion algorithms for as.directed: [object Object],[object Object]

Conversion algorithms for as.undirected: [object Object],[object Object],[object Object]

See Also

simplify for removing multiple and/or loop edges from a graph.

Examples

g <- graph.ring(10)
as.directed(g, "mutual")
g2 <- graph.star(10)
as.undirected(g)

# Combining edge attributes
g3 <- graph.ring(10, directed=TRUE, mutual=TRUE)
E(g3)$weight <- seq_len(ecount(g3))
ug3 <- as.undirected(g3)
print(ug3, e=TRUE)
x11(width=10, height=5)
  layout(rbind(1:2))
  plot( g3, layout=layout.circle, edge.label=E(g3)$weight)
  plot(ug3, layout=layout.circle, edge.label=E(ug3)$weight)

g4 <- graph(c(1,2, 3,2,3,4,3,4, 5,4,5,4,
              6,7, 7,6,7,8,7,8, 8,7,8,9,8,9,
              9,8,9,8,9,9, 10,10,10,10))
E(g4)$weight <- seq_len(ecount(g4))
ug4 <- as.undirected(g4, mode="mutual",
              edge.attr.comb=list(weight=length))
print(ug4, e=TRUE)