Specifies how to use the direction of the edges.
For out, the sorting order ensures that each node comes
before all nodes to which it has edges, so nodes with no incoming
edges go first. For in
Value
A numeric vector containing vertex ids in topologically sorted order.
concept
Topological sort
Details
Every DAG has at least one topological sort, and may have many.
This function returns a possible topological sort among them. If the
graph is not acyclic (it has at least one cycle), a partial topological
sort is returned and a warning is issued.