Copyright | (c) The University of Glasgow 2002 |
---|---|
License | BSD-style (see the file libraries/base/LICENSE) |
Maintainer | libraries@haskell.org |
Portability | portable |
Safe Haskell | Safe |
Language | Haskell98 |
Finite Graphs
The
type is an adjacency list representation of a finite, directed
graph with vertices of type Graph
Int
.
The
type represents a
strongly-connected component
of a graph.SCC
Implementation
The implementation is based on
- Structuring Depth-First Search Algorithms in Haskell, by David King and John Launchbury, http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.52.6526
Synopsis
- type Graph = Array Vertex [Vertex]
- type Bounds = (Vertex, Vertex)
- type Edge = (Vertex, Vertex)
- type Vertex = Int
- type Table a = Array Vertex a
- graphFromEdges :: Ord key => [(node, key, [key])] -> (Graph, Vertex -> (node, key, [key]), key -> Maybe Vertex)
- graphFromEdges' :: Ord key => [(node, key, [key])] -> (Graph, Vertex -> (node, key, [key]))
- buildG :: Bounds -> [Edge] -> Graph
- vertices :: Graph -> [Vertex]
- edges :: Graph -> [Edge]
- outdegree :: Graph -> Array Vertex Int
- indegree :: Graph -> Array Vertex Int
- transposeG :: Graph -> Graph
- dfs :: Graph -> [Vertex] -> Forest Vertex
- dff :: Graph -> Forest Vertex
- topSort :: Graph -> [Vertex]
- components :: Graph -> Forest Vertex
- scc :: Graph -> Forest Vertex
- bcc :: Graph -> Forest [Vertex]
- reachable :: Graph -> Vertex -> [Vertex]
- path :: Graph -> Vertex -> Vertex -> Bool
- data SCC vertex
- = AcyclicSCC vertex
- | CyclicSCC [vertex]
- stronglyConnComp :: Ord key => [(node, key, [key])] -> [SCC node]
- stronglyConnCompR :: Ord key => [(node, key, [key])] -> [SCC (node, key, [key])]
- flattenSCC :: SCC vertex -> [vertex]
- flattenSCCs :: [SCC a] -> [a]
- type Forest a = [Tree a]
- data Tree a = Node a (Forest a)
Graphs
type Graph = Array Vertex [Vertex] Source #
Adjacency list representation of a graph, mapping each vertex to its list of successors.
type Table a = Array Vertex a Source #
Table indexed by a contiguous set of vertices.
Note: This is included for backwards compatibility.
Graph Construction
graphFromEdges :: Ord key => [(node, key, [key])] -> (Graph, Vertex -> (node, key, [key]), key -> Maybe Vertex) Source #
Build a graph from a list of nodes uniquely identified by keys, with a list of keys of nodes this node should have edges to.
This function takes an adjacency list representing a graph with vertices of
type key
labeled by values of type node
and produces a Graph
-based
representation of that list. The Graph
result represents the shape of the
graph, and the functions describe a) how to retrieve the label and adjacent
vertices of a given vertex, and b) how to retrive a vertex given a key.
(graph, nodeFromVertex, vertexFromKey) = graphFromEdges edgeList
graph :: Graph
is the raw, array based adjacency list for the graph.nodeFromVertex :: Vertex -> (node, key, [key])
returns the node associated with the given 0-basedInt
vertex; see warning below.vertexFromKey :: key -> Maybe Vertex
returns theInt
vertex for the key if it exists in the graph,Nothing
otherwise.
To safely use this API you must either extract the list of vertices directly
from the graph or first call vertexFromKey k
to check if a vertex
corresponds to the key k
. Once it is known that a vertex exists you can use
nodeFromVertex
to access the labelled node and adjacent vertices. See below
for examples.
Note: The out-list may contain keys that don't correspond to nodes of the graph; they are ignored.
Warning: The nodeFromVertex
function will cause a runtime exception if the
given Vertex
does not exist.
Examples
An empty graph.
(graph, nodeFromVertex, vertexFromKey) = graphFromEdges [] graph = array (0,-1) []
A graph where the out-list references unspecified nodes ('c'
), these are
ignored.
(graph, _, _) = graphFromEdges [("a", 'a', ['b']), ("b", 'b', ['c'])] array (0,1) [(0,[1]),(1,[])]
A graph with 3 vertices: ("a") -> ("b") -> ("c")
(graph, nodeFromVertex, vertexFromKey) = graphFromEdges [("a", 'a', ['b']), ("b", 'b', ['c']), ("c", 'c', [])] graph == array (0,2) [(0,[1]),(1,[2]),(2,[])] nodeFromVertex 0 == ("a",'a',"b") vertexFromKey 'a' == Just 0
Get the label for a given key.
let getNodePart (n, _, _) = n (graph, nodeFromVertex, vertexFromKey) = graphFromEdges [("a", 'a', ['b']), ("b", 'b', ['c']), ("c", 'c', [])] getNodePart . nodeFromVertex <$> vertexFromKey 'a' == Just "A"
graphFromEdges' :: Ord key => [(node, key, [key])] -> (Graph, Vertex -> (node, key, [key])) Source #
Identical to graphFromEdges
, except that the return value
does not include the function which maps keys to vertices. This
version of graphFromEdges
is for backwards compatibility.
buildG :: Bounds -> [Edge] -> Graph Source #
Build a graph from a list of edges.
Warning: This function will cause a runtime exception if a vertex in the edge
list is not within the given Bounds
.
Examples
buildG (0,-1) [] == array (0,-1) [] buildG (0,2) [(0,1), (1,2)] == array (0,1) [(0,[1]),(1,[2])] buildG (0,2) [(0,1), (0,2), (1,2)] == array (0,2) [(0,[2,1]),(1,[2]),(2,[])]
Graph Properties
vertices :: Graph -> [Vertex] Source #
Returns the list of vertices in the graph.
Examples
vertices (buildG (0,-1) []) == []
vertices (buildG (0,2) [(0,1),(1,2)]) == [0,1,2]
edges :: Graph -> [Edge] Source #
Returns the list of edges in the graph.
Examples
edges (buildG (0,-1) []) == []
edges (buildG (0,2) [(0,1),(1,2)]) == [(0,1),(1,2)]
outdegree :: Graph -> Array Vertex Int Source #
A table of the count of edges from each node.
Examples
outdegree (buildG (0,-1) []) == array (0,-1) []
outdegree (buildG (0,2) [(0,1), (1,2)]) == array (0,2) [(0,1),(1,1),(2,0)]
indegree :: Graph -> Array Vertex Int Source #
A table of the count of edges into each node.
Examples
indegree (buildG (0,-1) []) == array (0,-1) []
indegree (buildG (0,2) [(0,1), (1,2)]) == array (0,2) [(0,0),(1,1),(2,1)]
Graph Transformations
transposeG :: Graph -> Graph Source #
The graph obtained by reversing all edges.
Examples
transposeG (buildG (0,2) [(0,1), (1,2)]) == array (0,2) [(0,[]),(1,[0]),(2,[1])]
Graph Algorithms
dfs :: Graph -> [Vertex] -> Forest Vertex Source #
A spanning forest of the part of the graph reachable from the listed vertices, obtained from a depth-first search of the graph starting at each of the listed vertices in order.
dff :: Graph -> Forest Vertex Source #
A spanning forest of the graph, obtained from a depth-first search of the graph starting from each vertex in an unspecified order.
topSort :: Graph -> [Vertex] Source #
A topological sort of the graph. The order is partially specified by the condition that a vertex i precedes j whenever j is reachable from i but not vice versa.
components :: Graph -> Forest Vertex Source #
The connected components of a graph. Two vertices are connected if there is a path between them, traversing edges in either direction.
scc :: Graph -> Forest Vertex Source #
The strongly connected components of a graph, in reverse topological order.
Examples
scc (buildG (0,3) [(3,1),(1,2),(2,0),(0,1)]) == [Node {rootLabel = 0, subForest = [Node {rootLabel = 1, subForest = [Node {rootLabel = 2, subForest = []}]}]} ,Node {rootLabel = 3, subForest = []}]
bcc :: Graph -> Forest [Vertex] Source #
The biconnected components of a graph. An undirected graph is biconnected if the deletion of any vertex leaves it connected.
reachable :: Graph -> Vertex -> [Vertex] Source #
Returns the list of vertices reachable from a given vertex.
Examples
reachable (buildG (0,0) []) 0 == [0]
reachable (buildG (0,2) [(0,1), (1,2)]) 0 == [0,1,2]
path :: Graph -> Vertex -> Vertex -> Bool Source #
Returns True
if the second vertex reachable from the first.
Examples
path (buildG (0,0) []) 0 0 == True
path (buildG (0,2) [(0,1), (1,2)]) 0 2 == True
path (buildG (0,2) [(0,1), (1,2)]) 2 0 == False
Strongly Connected Components
Strongly connected component.
AcyclicSCC vertex | A single vertex that is not in any cycle. |
CyclicSCC [vertex] | A maximal set of mutually reachable vertices. |
Instances
Functor SCC Source # | Since: 0.5.4 |
Foldable SCC Source # | Since: 0.5.9 |
Defined in Data.Graph fold :: Monoid m => SCC m -> m # foldMap :: Monoid m => (a -> m) -> SCC a -> m # foldr :: (a -> b -> b) -> b -> SCC a -> b # foldr' :: (a -> b -> b) -> b -> SCC a -> b # foldl :: (b -> a -> b) -> b -> SCC a -> b # foldl' :: (b -> a -> b) -> b -> SCC a -> b # foldr1 :: (a -> a -> a) -> SCC a -> a # foldl1 :: (a -> a -> a) -> SCC a -> a # elem :: Eq a => a -> SCC a -> Bool # maximum :: Ord a => SCC a -> a # | |
Traversable SCC Source # | Since: 0.5.9 |
Eq1 SCC Source # | Since: 0.5.9 |
Read1 SCC Source # | Since: 0.5.9 |
Show1 SCC Source # | Since: 0.5.9 |
Eq vertex => Eq (SCC vertex) Source # | Since: 0.5.9 |
Data vertex => Data (SCC vertex) Source # | Since: 0.5.9 |
Defined in Data.Graph gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> SCC vertex -> c (SCC vertex) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (SCC vertex) # toConstr :: SCC vertex -> Constr # dataTypeOf :: SCC vertex -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (SCC vertex)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (SCC vertex)) # gmapT :: (forall b. Data b => b -> b) -> SCC vertex -> SCC vertex # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> SCC vertex -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> SCC vertex -> r # gmapQ :: (forall d. Data d => d -> u) -> SCC vertex -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> SCC vertex -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> SCC vertex -> m (SCC vertex) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> SCC vertex -> m (SCC vertex) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> SCC vertex -> m (SCC vertex) # | |
Read vertex => Read (SCC vertex) Source # | Since: 0.5.9 |
Show vertex => Show (SCC vertex) Source # | Since: 0.5.9 |
Generic (SCC vertex) Source # | |
NFData a => NFData (SCC a) Source # | |
Defined in Data.Graph | |
Generic1 SCC Source # | |
type Rep (SCC vertex) Source # | Since: 0.5.9 |
Defined in Data.Graph type Rep (SCC vertex) = D1 (MetaData "SCC" "Data.Graph" "containers-0.6.1.1-6v37pp0b3aw8K2hP4DIfuq" False) (C1 (MetaCons "AcyclicSCC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 vertex)) :+: C1 (MetaCons "CyclicSCC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 [vertex]))) | |
type Rep1 SCC Source # | Since: 0.5.9 |
Defined in Data.Graph type Rep1 SCC = D1 (MetaData "SCC" "Data.Graph" "containers-0.6.1.1-6v37pp0b3aw8K2hP4DIfuq" False) (C1 (MetaCons "AcyclicSCC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) Par1) :+: C1 (MetaCons "CyclicSCC" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec1 []))) |
Construction
:: Ord key | |
=> [(node, key, [key])] | The graph: a list of nodes uniquely identified by keys, with a list of keys of nodes this node has edges to. The out-list may contain keys that don't correspond to nodes of the graph; such edges are ignored. |
-> [SCC node] |
The strongly connected components of a directed graph, reverse topologically sorted.
Examples
stronglyConnComp [("a",0,[1]),("b",1,[2,3]),("c",2,[1]),("d",3,[3])] == [CyclicSCC ["d"],CyclicSCC ["b","c"],AcyclicSCC "a"]
:: Ord key | |
=> [(node, key, [key])] | The graph: a list of nodes uniquely identified by keys, with a list of keys of nodes this node has edges to. The out-list may contain keys that don't correspond to nodes of the graph; such edges are ignored. |
-> [SCC (node, key, [key])] | Reverse topologically sorted |
The strongly connected components of a directed graph, reverse topologically
sorted. The function is the same as stronglyConnComp
, except that
all the information about each node retained.
This interface is used when you expect to apply SCC
to
(some of) the result of SCC
, so you don't want to lose the
dependency information.
Examples
stronglyConnCompR [("a",0,[1]),("b",1,[2,3]),("c",2,[1]),("d",3,[3])] == [CyclicSCC [("d",3,[3])],CyclicSCC [("b",1,[2,3]),("c",2,[1])],AcyclicSCC ("a",0,[1])]
Conversion
flattenSCC :: SCC vertex -> [vertex] Source #
The vertices of a strongly connected component.
flattenSCCs :: [SCC a] -> [a] Source #
The vertices of a list of strongly connected components.
Trees
Non-empty, possibly infinite, multi-way trees; also known as rose trees.
Instances
Monad Tree Source # | |
Functor Tree Source # | |
MonadFix Tree Source # | Since: 0.5.11 |
Applicative Tree Source # | |
Foldable Tree Source # | |
Defined in Data.Tree fold :: Monoid m => Tree m -> m # foldMap :: Monoid m => (a -> m) -> Tree a -> m # foldr :: (a -> b -> b) -> b -> Tree a -> b # foldr' :: (a -> b -> b) -> b -> Tree a -> b # foldl :: (b -> a -> b) -> b -> Tree a -> b # foldl' :: (b -> a -> b) -> b -> Tree a -> b # foldr1 :: (a -> a -> a) -> Tree a -> a # foldl1 :: (a -> a -> a) -> Tree a -> a # elem :: Eq a => a -> Tree a -> Bool # maximum :: Ord a => Tree a -> a # | |
Traversable Tree Source # | |
Eq1 Tree Source # | Since: 0.5.9 |
Ord1 Tree Source # | Since: 0.5.9 |
Read1 Tree Source # | Since: 0.5.9 |
Show1 Tree Source # | Since: 0.5.9 |
MonadZip Tree Source # | |
Eq a => Eq (Tree a) Source # | |
Data a => Data (Tree a) Source # | |
Defined in Data.Tree gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Tree a -> c (Tree a) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Tree a) # toConstr :: Tree a -> Constr # dataTypeOf :: Tree a -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Tree a)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Tree a)) # gmapT :: (forall b. Data b => b -> b) -> Tree a -> Tree a # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Tree a -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Tree a -> r # gmapQ :: (forall d. Data d => d -> u) -> Tree a -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Tree a -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Tree a -> m (Tree a) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Tree a -> m (Tree a) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Tree a -> m (Tree a) # | |
Read a => Read (Tree a) Source # | |
Show a => Show (Tree a) Source # | |
Generic (Tree a) Source # | |
NFData a => NFData (Tree a) Source # | |
Generic1 Tree Source # | |
type Rep (Tree a) Source # | Since: 0.5.8 |
Defined in Data.Tree type Rep (Tree a) = D1 (MetaData "Tree" "Data.Tree" "containers-0.6.1.1-6v37pp0b3aw8K2hP4DIfuq" False) (C1 (MetaCons "Node" PrefixI True) (S1 (MetaSel (Just "rootLabel") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 a) :*: S1 (MetaSel (Just "subForest") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (Forest a)))) | |
type Rep1 Tree Source # | Since: 0.5.8 |
Defined in Data.Tree type Rep1 Tree = D1 (MetaData "Tree" "Data.Tree" "containers-0.6.1.1-6v37pp0b3aw8K2hP4DIfuq" False) (C1 (MetaCons "Node" PrefixI True) (S1 (MetaSel (Just "rootLabel") NoSourceUnpackedness NoSourceStrictness DecidedLazy) Par1 :*: S1 (MetaSel (Just "subForest") NoSourceUnpackedness NoSourceStrictness DecidedLazy) ([] :.: Rec1 Tree))) |