Struct daggy::Dag
[−]
[src]
pub struct Dag<N, E, Ix: IndexType = DefIndex> { // some fields omitted }
A Directed acyclic graph (DAG) data structure.
Dag is a thin wrapper around petgraph's Graph data structure, providing a refined API for
dealing specifically with DAGs.
Note: The following documentation is adapted from petgraph's Graph documentation.
Dag is parameterized over the node weight N, edge weight E and index type Ix.
NodeIndex is a type that acts as a reference to nodes, but these are only stable across certain operations. Removing nodes may shift other indices. Adding kids to the Dag keeps all indices stable, but removing a node will force the last node to shift its index to take its place.
The fact that the node indices in the Dag are numbered in a compact interval from 0 to n-1 simplifies some graph algorithms.
The Ix parameter is u32 by default. The goal is that you can ignore this parameter completely unless you need a very large Dag -- then you can use usize.
The Dag also offers methods for accessing the underlying Graph, which can be useful for taking advantage of petgraph's various graph-related algorithms.
Methods
impl<N, E, Ix = DefIndex> Dag<N, E, Ix> where Ix: IndexType[src]
fn new() -> Self
Create a new, empty Dag.
fn with_capacity(nodes: usize, edges: usize) -> Self
Create a new Dag with estimated capacity for its node and edge Vecs.
fn node_count(&self) -> usize
The total number of nodes in the Dag.
fn edge_count(&self) -> usize
The total number of edgees in the Dag.
fn graph(&self) -> &PetGraph<N, E, Ix>
Borrow the Dag's underlying PetGraph<N, Ix>.
All existing indices may be used to index into this PetGraph the same way they may be
used to index into the Dag.
fn into_graph(self) -> PetGraph<N, E, Ix>
Take ownership of the Dag and return the internal PetGraph.
All existing indices may be used to index into this PetGraph the same way they may be
used to index into the Dag.
fn add_node(&mut self, weight: N) -> NodeIndex<Ix>
Add a new node to the Dag with the given weight.
Computes in O(1) time.
Returns the index of the new node.
Note: If you're adding a new node and immediately adding a single edge to that node from some other node, consider using the add_child or add_parent methods instead for better performance.
Panics if the Graph is at the maximum number of nodes for its index type.
fn add_edge(&mut self, a: NodeIndex<Ix>, b: NodeIndex<Ix>, weight: E) -> Result<EdgeIndex<Ix>, WouldCycle<E>>
Add a new directed edge to the Dag with the given weight.
The added edge will be in the direction a -> b
Checks if the edge would create a cycle in the Graph.
If adding the edge would not cause the graph to cycle, the edge will be added and its
EdgeIndex returned.
If adding the edge would cause the graph to cycle, the edge will not be added and
instead a WouldCycle<E> error with the given weight will be returned.
Computes in O(t) time where "t" is the time taken to check if adding the edge would
cause a cycle in the graph. See petgraph's is_cyclic_directed
function for more details.
Note: Dag allows adding parallel ("duplicate") edges. If you want to avoid this, use
update_edge instead.
Note: If you're adding a new node and immediately adding a single edge to that node from some other node, consider using the add_child or add_parent methods instead for better performance.
**Panics if the Graph is at the maximum number of nodes for its index type.
fn update_edge(&mut self, a: NodeIndex<Ix>, b: NodeIndex<Ix>, weight: E) -> Result<EdgeIndex<Ix>, WouldCycle<E>>
Update the edge from nodes a -> b with the given weight.
If the edge doesn't already exist, it will be added using the add_edge method.
Please read the add_edge for more important details.
Checks if the edge would create a cycle in the Graph.
Computes in O(t + e) time where "t" is the complexity of add_edge and e is the number
of edges connected to the nodes a and b.
Returns the index of the edge, or a WouldCycle error if adding the edge would create a
cycle.
Note: If you're adding a new node and immediately adding a single edge to that node from
some parent node, consider using the add_child
method instead for better performance.
Panics if the Graph is at the maximum number of nodes for its index type.
fn add_parent(&mut self, child: NodeIndex<Ix>, edge: E, node: N) -> (EdgeIndex<Ix>, NodeIndex<Ix>)
Add a new edge and parent node to the node at the given NodeIndex.
Returns both the edge's EdgeIndex and the node's NodeIndex.
node -> edge -> child
Computes in O(1) time.
This is faster than using add_node and add_edge. This is because we don't have to check
if the graph would cycle when adding an edge to the new node, as we know it it will be the
only edge connected to that node.
Panics if the given child node doesn't exist.
Panics if the Graph is at the maximum number of edges for its index.
fn add_child(&mut self, parent: NodeIndex<Ix>, edge: E, node: N) -> (EdgeIndex<Ix>, NodeIndex<Ix>)
Add a new edge and child node to the node at the given NodeIndex.
Returns both the edge's EdgeIndex and the node's NodeIndex.
child -> edge -> node
Computes in O(1) time.
This is faster than using add_node and add_edge. This is because we don't have to check
if the graph would cycle when adding an edge to the new node, as we know it it will be the
only edge connected to that node.
Panics if the given parent node doesn't exist.
Panics if the Graph is at the maximum number of edges for its index.
fn node_weight(&self, node: NodeIndex<Ix>) -> Option<&N>
Borrow the weight from the node at the given index.
fn node_weight_mut(&mut self, node: NodeIndex<Ix>) -> Option<&mut N>
Mutably borrow the weight from the node at the given index.
fn edge_weight(&self, edge: EdgeIndex<Ix>) -> Option<&E>
Borrow the weight from the edge at the given index.
fn edge_weight_mut(&mut self, edge: EdgeIndex<Ix>) -> Option<&mut E>
Mutably borrow the weight from the edge at the given index.
fn index_twice_mut<A, B>(&mut self, a: A, b: B) -> (&mut PetGraph<N, E, Ix>::Output, &mut PetGraph<N, E, Ix>::Output) where PetGraph<N, E, Ix>: IndexMut<A> + IndexMut<B>, A: GraphIndex, B: GraphIndex
Index the Dag by two indices.
Both indices can be either NodeIndexs, EdgeIndexs or a combination of the two.
Panics if the indices are equal or if they are out of bounds.
fn remove_node(&mut self, node: NodeIndex<Ix>) -> Option<N>
Remove the node at the given index from the Dag and return it if it exists.
Note: Calling this may shift (and in turn invalidate) previously returned node indices!
fn remove_edge(&mut self, e: EdgeIndex<Ix>) -> Option<E>
Remove an edge and return its weight, or None if it didn't exist.
Computes in O(e') time, where e' is the size of four particular edge lists, for the nodes of e and the nodes of another affected edge.
fn parents(&self, child: NodeIndex<Ix>) -> Parents<E, Ix>
An iterator over all nodes that are parents to the node at the given index.
The returned iterator yields EdgeIndex<Ix>s.
fn walk_parents(&self, child: NodeIndex<Ix>) -> WalkParents<Ix>
A "walker" object that may be used to step through the parents of the given child node.
Unlike the Parents type, WalkParents does not borrow the Dag's PetGraph.
fn children(&self, parent: NodeIndex<Ix>) -> Children<E, Ix>
An iterator over all nodes that are children to the node at the given index.
The returned iterator yields EdgeIndex<Ix>s.
fn walk_children(&self, parent: NodeIndex<Ix>) -> WalkChildren<Ix>
A "walker" object that may be used to step through the children of the given parent node.
Unlike the Children type, WalkChildren does not borrow the Dag's PetGraph.
Trait Implementations
impl<N: Debug, E: Debug, Ix: Debug + IndexType> Debug for Dag<N, E, Ix>[src]
impl<N: Clone, E: Clone, Ix: Clone + IndexType> Clone for Dag<N, E, Ix>[src]
fn clone(&self) -> Dag<N, E, Ix>
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)1.0.0
Performs copy-assignment from source. Read more
impl<N, E, Ix> Index<NodeIndex<Ix>> for Dag<N, E, Ix> where Ix: IndexType[src]
type Output = N
The returned type after indexing
fn index(&self, index: NodeIndex<Ix>) -> &N
The method for the indexing (Foo[Bar]) operation
impl<N, E, Ix> IndexMut<NodeIndex<Ix>> for Dag<N, E, Ix> where Ix: IndexType[src]
fn index_mut(&mut self, index: NodeIndex<Ix>) -> &mut N
The method for the indexing (Foo[Bar]) operation
impl<N, E, Ix> Index<EdgeIndex<Ix>> for Dag<N, E, Ix> where Ix: IndexType[src]
type Output = E
The returned type after indexing
fn index(&self, index: EdgeIndex<Ix>) -> &E
The method for the indexing (Foo[Bar]) operation