Community.hs

module IGraph.Community
    ( CommunityOpt(..)
    , CommunityMethod(..)
    , findCommunity
    ) where

import Control.Monad
import Control.Applicative ((<$>))
import Foreign
import Foreign.C.Types
import System.IO.Unsafe (unsafePerformIO)
import Data.List
import Data.Ord
import Data.Function (on)
import Data.Default.Class

import IGraph
import IGraph.Mutable (U)
import IGraph.Internal.Data
import IGraph.Internal.Constants
import IGraph.Internal.Community
import IGraph.Internal.Arpack

data CommunityOpt = CommunityOpt
    { _method :: CommunityMethod
    , _weights :: Maybe [Double]
    , _nIter :: Int  -- ^ [LeadingEigenvector] number of iterations, default is 10000
    , _nSpins :: Int  -- ^ [Spinglass] number of spins, default is 25
    , _startTemp :: Double  -- ^ [Spinglass] the temperature at the start
    , _stopTemp :: Double  -- ^ [Spinglass] the algorithm stops at this temperature
    , _coolFact :: Double  -- ^ [Spinglass] the cooling factor for the simulated annealing
    , _gamma :: Double  -- ^ [Spinglass] the gamma parameter of the algorithm. 
    }

data CommunityMethod = LeadingEigenvector
                     | Spinglass

instance Default CommunityOpt where
    def = CommunityOpt
        { _method = LeadingEigenvector
        , _weights = Nothing
        , _nIter = 10000
        , _nSpins = 25
        , _startTemp = 1.0
        , _stopTemp = 0.01
        , _coolFact = 0.99
        , _gamma = 1.0
        }

findCommunity :: LGraph U v e -> CommunityOpt -> [[Int]]
findCommunity gr opt = unsafePerformIO $ do
    result <- igraphVectorNew 0
    ws <- case _weights opt of
        Just w -> listToVector w
        _ -> liftM VectorPtr $ newForeignPtr_ $ castPtr nullPtr

    case _method opt of
        LeadingEigenvector -> do
            ap <- igraphArpackNew
            igraphCommunityLeadingEigenvector (_graph gr) ws nullPtr result
                                              (_nIter opt) ap nullPtr False
                                              nullPtr nullPtr nullPtr
                                              nullFunPtr nullPtr  
        Spinglass ->
            igraphCommunitySpinglass (_graph gr) ws nullPtr nullPtr result
                                     nullPtr (_nSpins opt) False (_startTemp opt)
                                     (_stopTemp opt) (_coolFact opt)
                                     IgraphSpincommUpdateConfig (_gamma opt)
                                     IgraphSpincommImpOrig 1.0

    liftM ( map (fst . unzip) . groupBy ((==) `on` snd)
          . sortBy (comparing snd) . zip [0..] ) $ vectorPtrToList result