Random directed acyclic graph

Generate a random directed acyclic graph (DAG)

random_dag(V, maxpar = 3, wgt = 0.1)

Arguments

V

The set of vertices.

maxpar

The maximum number of parents each node can have

wgt

A parameter controlling how likely it is for a node to have a certain number of parents; see 'Details'.

Value

An igraph object.

Details

If the maximum number of parents for a node is, say 3 and wgt=0.1, then the probability of the node ending up with 0,1,2,3 parents is proportional to 0.1^0, 0.1^1, 0.1^2, 0.1^3.

Author

Søren Højsgaard, sorenh@math.aau.dk

Examples

dg   <- random_dag(1:1000, maxpar=5, wgt=.9)
table(sapply(vpar(dg),length))
#> 
#>   1   2   3   4   5   6 
#> 216 209 158 151 135 131 

dg   <- random_dag(1:1000, maxpar=5, wgt=.5)
table(sapply(vpar(dg),length))
#> 
#>   1   2   3   4   5   6 
#> 510 264 126  59  25  16 

dg   <- random_dag(1:1000, maxpar=5, wgt=.1)
table(sapply(vpar(dg),length))
#> 
#>   1   2   3   4 
#> 893  96   9   2