{-# LANGUAGE OverlappingInstances , UndecidableInstances , TypeSynonymInstances , FlexibleInstances #-} {- | Module : Data.Graph.Analysis.Utils Description : Utility functions Copyright : (c) Ivan Lazar Miljenovic 2008 License : 2-Clause BSD Maintainer : Ivan.Miljenovic@gmail.com This module defines various utility functions used throughout. -} module Data.Graph.Analysis.Utils ( -- * Graph functions -- ** Data extraction node, label, edge, eLabel, addLabels, filterNodes, filterNodes', -- ** Graph manipulation pathValues, undir, oneWay, nlmap, -- ** Graph layout -- | These next two are re-exported from "Data.GraphViz" AttributeNode, AttributeEdge, dotizeGraph, toPosGraph, getPositions, -- ** Cluster functions createLookup, setCluster, assignCluster, -- * List functions single, longerThan, longest, groupElems, sortMinMax, blockPrint, shuffle, -- * Statistics functions mean, statistics, statistics', -- * Other functions fixPoint, fixPointGraphs, fixPointBy, sq, fI ) where import Data.Graph.Analysis.Types import Data.Graph.Inductive.Graph import Data.GraphViz import Data.List import Data.Maybe import Data.Function import qualified Data.Set as Set import qualified Data.IntMap as IMap import Data.IntMap(IntMap) import Control.Monad import Control.Arrow import System.Random import System.IO.Unsafe(unsafePerformIO) -- ----------------------------------------------------------------------------- -- | Extracting data from graphs. -- | The node number of an 'LNode'. node :: LNode a -> Node node = fst -- | The label of an 'LNode' label :: LNode a -> a label = snd -- | Extract the 'Edge' from the 'LEdge'. edge :: LEdge b -> Edge edge (n1,n2,_) = (n1,n2) -- | The label of an 'LEdge' eLabel :: LEdge b -> b eLabel (_,_,b) = b -- | Obtain the labels for a list of 'Node's. -- It is assumed that each 'Node' is indeed present in the given graph. addLabels :: (Graph g) => g a b -> [Node] -> [LNode a] addLabels gr = map (ap (,) (fromJust . lab gr)) -- | Find all the labelled nodes in the graph that match the given predicate. filterNodes :: (Graph g) => (g a b -> LNode a -> Bool) -> g a b -> [LNode a] filterNodes p g = filter (p g) (labNodes g) -- | Find all the nodes in the graph that match the given predicate. filterNodes' :: (Graph g) => (g a b -> Node -> Bool) -> g a b -> [Node] filterNodes' p g = filter (p g) (nodes g) -- ----------------------------------------------------------------------------- -- | Manipulating graphs. -- | Extract the actual 'LNode's from an 'LPath'. pathValues :: LPath a -> [LNode a] pathValues (LP lns) = lns {- | Make the graph undirected, i.e. for every edge from A to B, there exists an edge from B to A. The provided function 'Data.Graph.Inductive.Basic.undir' duplicates loops as well, which isn't wanted. It is assumed that no edges are already duplicates [i.e. if there exists an edge (n1,n2), then there doesn't exist (n2,n1)]. This function also preserves edge labels: if two edges exist between two nodes with different edge labels, then both edges will be duplicated. -} undir :: (Eq b, DynGraph gr) => gr a b -> gr a b undir = gmap dupEdges where dupEdges (p,n,l,s) = (ps',n,l,ps) where ps = nub $ p ++ s ps' = snd $ partition isLoop ps isLoop (_,n') = n == n' -- | This is a pseudo-inverse of 'undir': any edges that are both successor -- and predecessor become successor edges only. oneWay :: (DynGraph g, Eq b) => g a b -> g a b oneWay = gmap rmPre where rmPre (p,n,l,s) = (p \\ s,n,l,s) -- | Map over the labels on the nodes, using the node values as well. nlmap :: (DynGraph gr) => (LNode a -> c) -> gr a b -> gr c b nlmap f = gmap f' where f' (p,n,l,s) = (p,n,f (n,l),s) -- ----------------------------------------------------------------------------- {- | Spatial positioning of graphs. Use the 'graphToGraph' function in "Data.GraphViz" to determine potential graph layouts. -} -- | Pass the plain graph through 'graphToGraph'. This is an IO action, -- however since the state doesn't change it's safe to use 'unsafePerformIO' -- to convert this to a normal function. dotizeGraph :: (DynGraph gr, Ord b) => gr a b -> gr (AttributeNode a) (AttributeEdge b) dotizeGraph g = unsafePerformIO $ graphToGraph g gAttrs noAttrs noAttrs where gAttrs = [] noAttrs = const [] -- | Convert the graph into one with positions stored in the node labels. toPosGraph :: (DynGraph gr, Ord b) => gr a b -> gr (PosLabel a) b toPosGraph = nlmap getPos . emap rmAttrs . dotizeGraph where rmAttrs = snd isPoint attr = case attr of (Pos _) -> True _ -> False getPos (n,(as,l)) = PLabel { xPos = x , yPos = y , pnode = n , plabel = l } where -- Assume that positions can't be doubles. (Pos (PointList ((Point x y):_))) = fromJust $ find isPoint as -- | Returns the positions of the nodes in the graph, as found using Graphviz. getPositions :: (DynGraph gr, Ord b) => gr a b -> [PosLabel a] getPositions = map label . labNodes . toPosGraph -- ----------------------------------------------------------------------------- -- | Cluster utility functions. -- | Create a cluster-lookup 'IntMap'. createLookup :: [[Node]] -> IntMap Int createLookup = IMap.fromList . concatMap addCluster . zip [1..] where addCluster (k,ns) = map (flip (,) k) ns -- | Used when the clusters are assigned in a lookup 'IntMap' instance. setCluster :: (DynGraph gr) => IntMap Int -> gr a b -> gr (GenCluster a) b setCluster m = nlmap assClust where assClust (n,l) = GC (m IMap.! n) l -- | A function to convert an 'LNode' to the required 'NodeCluster' -- for use with the 'Graphviz' library. assignCluster :: (ClusterLabel a c) => LNode a -> NodeCluster c a assignCluster nl@(_,a) = C (cluster a) (N nl) -- ----------------------------------------------------------------------------- -- | List utility functions. -- | Return true if and only if the list contains a single element. single :: [a] -> Bool single [_] = True single _ = False -- | If we need to only tell if the list contains more than @n@ elements, -- there's no need to find its length. longerThan :: Int -> [a] -> Bool longerThan n = not . null . drop n -- | Returns the longest list in a list of lists. longest :: [[a]] -> [a] longest = snd . maximumBy (compare `on` fst) . map addLength where addLength xs = (length xs,xs) -- | Group elements by the given grouping function. groupElems :: (Ord b) => (a -> b) -> [a] -> [(b,[a])] groupElems f = map createGroup . groupBy ((==) `on` fst) . sortBy (compare `on` fst) . map addOrd where addOrd a = (f a, a) createGroup bas@((b,_):_) = (b, map snd bas) -- This shouldn't ever happen, but let's suppress the -Wall warning. createGroup [] = error "Grouping resulted in an empty list!" -- | Returns the unique elements of the list in ascending order, -- as well as the minimum and maximum elements. sortMinMax :: (Ord a) => [a] -> ([a],a,a) sortMinMax as = (as',aMin,aMax) where aSet = Set.fromList as as' = Set.toAscList aSet aMin = Set.findMin aSet aMax = Set.findMax aSet -- | Attempt to convert a list of elements into a square format -- in as much of a square shape as possible. blockPrint :: (Show a) => [a] -> String blockPrint as = init -- Remove the final '\n' on the end. . unlines $ map unwords lns where showl a = let sa = show a in (sa, length sa) las = map showl as -- Scale this, to take into account the height:width ratio. sidelen :: Double -- Suppress defaulting messages sidelen = (1.75*) . sqrt . fromIntegral . sum $ map snd las slen = round sidelen serr = round $ sidelen/10 lns = unfoldr (takeLen slen serr) las -- | Using the given line length and allowed error, take the elements of -- the next line. takeLen :: Int -> Int -> [(String,Int)] -> Maybe ([String],[(String,Int)]) takeLen _ _ [] = Nothing takeLen len err ((a,l):als) = Just lr where lmax = len + err lr = if l > len then ([a],als) -- Overflow line of single item else (a:as,als') -- We subtract one here to take into account the space. (as,als') = takeLine (lmax - l - 1) als -- | Recursively build the rest of the line with given maximum length. takeLine :: Int -> [(String,Int)] -> ([String],[(String,Int)]) takeLine len als | null als = ([],als) | len <= 0 = ([],als) -- This should be covered by the next guard, -- but just in case... | l > len = ([],als) | otherwise = (a:as,als'') where ((a,l):als') = als len' = len - l - 1 -- Subtract 1 to account for the space (as,als'') = takeLine len' als' {- | Shuffle a list of elements. This isn't the most efficient version, but should serve for small lists. Adapted from: <http://www.cse.unsw.edu.au/~tsewell/shuffle.html> The adaptation mainly involved altering the code so that the new random seed is also returned. -} shuffle :: (RandomGen g) => g -> [a] -> ([a],g) shuffle g [] = ([],g) shuffle g [x] = ([x],g) shuffle g xs = randomMerge g'' ((shYs,yn),(shZs,zn)) where ((ys, yn), (zs, zn)) = splitAndCount xs (([], 0), ([], 0)) (shYs,g') = shuffle g ys (shZs,g'') = shuffle g' zs splitAndCount :: [a] -> (([a], Int), ([a], Int)) -> (([a], Int), ([a], Int)) splitAndCount [] result = result splitAndCount (x : xs) ((ys, yn), (zs, zn)) = splitAndCount xs ((x : zs, zn + 1), (ys, yn)) {- Taken from the original site: The idea is to merge two shuffled lists which come with given sizes. If the lists X and Y have sizes n and m, we should pick the first element of X with probability n / n + m and the first element of Y with probability m / n + m. As X and Y are shuffled, picking the first element is random among their original elements, and thus this constitutes a random choice of first element from the original set. -} randomMerge :: (RandomGen g) => g -> (([a], Int), ([a], Int)) -> ([a],g) randomMerge g (([],_),(ys,_)) = (ys,g) randomMerge g ((xs,_),([],_)) = (xs,g) randomMerge g ((x:xs,xn),(y:ys,yn)) = if n <= xn then first (x:) xg else first (y:) yg where xg = randomMerge g' ((xs, xn - 1), (y : ys, yn)) yg = randomMerge g' ((x : xs, xn), (ys, yn - 1)) (n, g') = randomR (1, xn + yn) g -- ----------------------------------------------------------------------------- -- | Statistics functions. -- | An efficient mean function by Don Stewart, available from: -- <http://cgi.cse.unsw.edu.au/~dons/blog/2008/05/16#fast> mean :: [Double] -> Double mean = go 0 0 where go :: Double -> Int -> [Double] -> Double go s l [] = s / fromIntegral l go s l (x:xs) = go (s+x) (l+1) xs -- | Calculate the mean and standard deviation of a list of elements. statistics :: [Double] -> (Double,Double) -- ^ (Mean, Standard Deviation) statistics as = (av,stdDev) where av = mean as stdDev = sqrt . mean $ map (sq . subtract av) as -- | Calculate the mean and standard deviation of a list of 'Int' values. statistics' :: [Int] -> (Int,Int) -- ^ (Mean, Standard Deviation) statistics' as = (av', stdDev') where (av,stdDev) = statistics $ map fromIntegral as av' = round av stdDev' = round stdDev -- ----------------------------------------------------------------------------- -- | Other utility functions. -- | Find the fixed point of a function with the given initial value. fixPoint :: (Eq a) => (a -> a) -> a -> a fixPoint f = fixPointBy (==) f -- | Find the fixed point of a function with the given initial value, -- using the given equality function. fixPointBy :: (a -> a -> Bool) -> (a -> a) -> a -> a fixPointBy eq f x = if (eq x x') then x' else fixPointBy eq f x' where x' = f x -- | Find the fixed point of a graph transformation function. fixPointGraphs :: (Eq a, Eq b, Graph g) => (g a b -> g a b) -> g a b -> g a b fixPointGraphs f = fixPointBy equal f -- | Squaring a number. sq :: (Num a) => a -> a sq x = x * x -- | Shorthand for 'fromIntegral' fI :: (Num a) => Int -> a fI = fromIntegral