forget to add igraphInit

src/IGraph.hs

@@ -42,6 +42,10 @@ module IGraph
 
     , nfilter
     , efilter
+
+    -- * Non-simple graphs: multiple and loop edges
+    , isSimple
+    , hasMultiple
     ) where
 
 import           Conduit
@@ -316,3 +320,16 @@ efilter f gr = runST $ do
     gr' <- thaw gr
     GM.delEdges deleted gr'
     unsafeFreeze gr'
+
+-- | Decides whether the input graph is a simple graph. A graph is a simple
+-- graph if it does not contain loop edges and multiple edges.
+isSimple :: Graph d v e -> Bool
+isSimple = unsafePerformIO . igraphIsSimple . _graph
+{-# INLINE isSimple #-}
+
+-- | Check whether the graph has at least one multiple edge. An edge is a
+-- multiple edge if there is another edge with the same head and tail vertices
+-- in the graph.
+hasMultiple :: Graph d v e -> Bool
+hasMultiple = unsafePerformIO . igraphHasMultiple . _graph
+{-# INLINE hasMultiple #-}

src/IGraph/Algorithms/Generators.chs

@@ -33,6 +33,7 @@ full :: forall d. SingI d
      -> Bool  -- ^ Whether to include self-edges (loops)
      -> Graph d () ()
 full n hasLoop = unsafePerformIO $ do
+    igraphInit
     gr <- MGraph <$> igraphFull n directed hasLoop
     M.initializeNullAttribute gr
     unsafeFreeze gr
@@ -49,6 +50,7 @@ full n hasLoop = unsafePerformIO $ do
 star :: Int    -- ^ The number of nodes
      -> Graph 'U () ()
 star n = unsafePerformIO $ do
+    igraphInit
     gr <- MGraph <$> igraphStar n IgraphStarUndirected 0
     M.initializeNullAttribute gr
     unsafeFreeze gr
@@ -87,11 +89,13 @@ erdosRenyiGame model self = do
 degreeSequenceGame :: [Int]   -- ^ Out degree
                    -> [Int]   -- ^ In degree
                    -> IO (Graph 'D () ())
-degreeSequenceGame out_deg in_deg = withList out_deg $ \out_deg' ->
-    withList in_deg $ \in_deg' -> do
-        gr <- MGraph <$> igraphDegreeSequenceGame out_deg' in_deg' IgraphDegseqSimple
-        M.initializeNullAttribute gr
-        unsafeFreeze gr
+degreeSequenceGame out_deg in_deg = do
+    igraphInit
+    withList out_deg $ \out_deg' ->
+        withList in_deg $ \in_deg' -> do
+            gr <- MGraph <$> igraphDegreeSequenceGame out_deg' in_deg' IgraphDegseqSimple
+            M.initializeNullAttribute gr
+            unsafeFreeze gr
 {#fun igraph_degree_sequence_game as ^
     { allocaIGraph- `IGraph' addIGraphFinalizer*
     , castPtr `Ptr Vector', castPtr `Ptr Vector', `Degseq'

src/IGraph/Algorithms/Structure.chs

@@ -14,6 +14,7 @@ import           Data.Either               (fromRight)
 import           Data.Hashable             (Hashable)
 import qualified Data.HashMap.Strict       as M
 import           Data.Serialize            (Serialize, decode)
+import Data.List (foldl')
 import           System.IO.Unsafe          (unsafePerformIO)
 import Data.Maybe
 import Data.Singletons (SingI)
@@ -134,6 +135,9 @@ pagerank :: SingI d
 pagerank gr reset ws d
     | n == 0 = []
     | isJust ws && length (fromJust ws) /= m = error "incorrect length of edge weight vector"
+    | isJust reset && length (fromJust reset) /= n = error
+        "incorrect length of node weight vector"
+    | fmap (foldl' (+) 0) reset == Just 0 = error "sum of node weight vector must be non-zero"
     | otherwise = unsafePerformIO $ alloca $ \p -> allocaVector $ \result ->
         withVerticesAll $ \vs -> withListMaybe ws $ \ws' -> do
             case reset of

src/IGraph/Internal.chs

@@ -56,6 +56,8 @@ module IGraph.Internal
     , addIGraphFinalizer
     , igraphNew
     , igraphCreate
+    , igraphIsSimple
+    , igraphHasMultiple
 
       -- * Selector and iterator for edge and vertex
       -- ** Igraph vertex selector
@@ -386,6 +388,17 @@ igraphNew n directed _ = igraphNew' n directed
                -- to the second, etc.
     } -> `CInt' void- #}
 
+-- | A graph is a simple graph if it does not contain loop edges and multiple edges.
+{#fun igraph_is_simple as ^
+    { `IGraph'
+    , alloca- `Bool' peekBool*
+    } -> `CInt' void- #}
+
+{#fun igraph_has_multiple as ^
+    { `IGraph'
+    , alloca- `Bool' peekBool*
+    } -> `CInt' void- #}
+
 {#fun igraph_to_directed as ^
     { `IGraph'   -- ^ The graph object to convert.
     , `ToDirected'   -- ^ Specifies the details of how exactly the conversion is

src/IGraph/Internal/C2HS.hs

@@ -4,7 +4,7 @@ module IGraph.Internal.C2HS (
   cIntConv, cFloatConv, cToBool, cFromBool, cToEnum, cFromEnum,
 
   -- * Composite marshalling functions
-  peekIntConv, peekFloatConv,
+  peekIntConv, peekFloatConv, peekBool
 
 ) where
 
@@ -64,10 +64,14 @@ cFromEnum  = cIntConv . fromEnum
 
 -- | Marshalling of numerals
 --
-{-# INLINE peekIntConv #-}
 peekIntConv :: (Storable a, Integral a, Integral b) => Ptr a -> IO b
 peekIntConv = liftM cIntConv . peek
+{-# INLINE peekIntConv #-}
+
+peekBool :: (Storable a, Eq a, Num a)  => Ptr a -> IO Bool
+peekBool = liftM cToBool . peek
+{-# INLINE peekBool #-}
 
-{-# INLINE peekFloatConv #-}
 peekFloatConv :: (Storable a, RealFloat a, RealFloat b) => Ptr a -> IO b
 peekFloatConv = liftM cFloatConv . peek
+{-# INLINE peekFloatConv #-}