add more generators

haskell-igraph.cabal

@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                haskell-igraph
-version:             0.3.0
+version:             0.3.1-dev
 synopsis:            Imcomplete igraph bindings
 description:         This is an attempt to create a complete bindings for the
                      igraph<"http://igraph.org/c/"> library.
@@ -10,7 +10,7 @@ license:             MIT
 license-file:        LICENSE
 author:              Kai Zhang
 maintainer:          kai@kzhang.org
-copyright:           (c) 2016 Kai Zhang
+copyright:           (c) 2016-2017 Kai Zhang
 category:            Math
 build-type:          Simple
 cabal-version:       >=1.24

src/IGraph/Generators.hs

 module IGraph.Generators
     ( ErdosRenyiModel(..)
     , erdosRenyiGame
+    , degreeSequenceGame
+    , rewire
     ) where
 
+import           Control.Monad                  (when)
+import           Data.Hashable                  (Hashable)
+
 import           IGraph
-import IGraph.Mutable
-import IGraph.Internal.Graph
 import           IGraph.Internal.Constants
+import           IGraph.Internal.Data
+import           IGraph.Internal.Graph
 import           IGraph.Internal.Initialization
+import           IGraph.Mutable
 
 data ErdosRenyiModel = GNP Int Double
                      | GNM Int Int
@@ -24,3 +30,24 @@ erdosRenyiGame (GNM n m) d self = do
     gp <- igraphInit >> igraphErdosRenyiGame IgraphErdosRenyiGnm n
         (fromIntegral m) (isD d) self
     unsafeFreeze $ MLGraph gp
+
+-- | Generates a random graph with a given degree sequence.
+degreeSequenceGame :: [Int]   -- ^ Out degree
+                   -> [Int]   -- ^ In degree
+                   -> IO (LGraph D () ())
+degreeSequenceGame out_deg in_deg = do
+    out_deg' <- listToVector $ map fromIntegral out_deg
+    in_deg' <- listToVector $ map fromIntegral in_deg
+    gp <- igraphDegreeSequenceGame out_deg' in_deg' IgraphDegseqSimpleNoMultiple
+    unsafeFreeze $ MLGraph gp
+
+-- | Randomly rewires a graph while preserving the degree distribution.
+rewire :: (Graph d, Hashable v, Read v, Eq v, Show v, Show e)
+       => Int    -- ^ Number of rewiring trials to perform.
+       -> LGraph d v e
+       -> IO (LGraph d v e)
+rewire n gr = do
+    (MLGraph gptr) <- thaw gr
+    err <- igraphRewire gptr n IgraphRewiringSimple
+    when (err /= 0) $ error "failed to rewire graph!"
+    unsafeFreeze $ MLGraph gptr

src/IGraph/Internal/Constants.chs

@@ -28,3 +28,9 @@ import Foreign
 
 {#enum igraph_erdos_renyi_t as ErdosRenyi {underscoreToCase}
     deriving (Show, Read, Eq) #}
+
+{#enum igraph_rewiring_t as Rewiring {underscoreToCase}
+    deriving (Show, Read, Eq) #}
+
+{#enum igraph_degseq_t as Degseq {underscoreToCase}
+    deriving (Show, Read, Eq) #}

src/IGraph/Internal/Graph.chs

@@ -54,6 +54,13 @@ igraphEdge g i = alloca $ \fr -> alloca $ \to -> do
 {#fun igraph_full as ^ { +, `Int', `Bool', `Bool' } -> `IGraphPtr' #}
 
 {#fun igraph_erdos_renyi_game as ^ { +, `ErdosRenyi', `Int', `Double', `Bool'
-    , `Bool'} -> `IGraphPtr' #}
+    , `Bool' } -> `IGraphPtr' #}
+
+{#fun igraph_degree_sequence_game as ^ { +, `VectorPtr', `VectorPtr'
+    , `Degseq' } -> `IGraphPtr' #}
+
+{#fun igraph_rewire as ^ { `IGraphPtr', `Int', `Rewiring' } -> `Int' #}
+
+
 
 {#fun igraph_isoclass_create as ^ { +, `Int', `Int', `Bool' } -> `IGraphPtr' #}