determenistic initial population for real-coded tests

Tests/Common.hs

@@ -37,10 +37,29 @@ undx = unimodalCrossoverRP
 sbx = simulatedBinaryCrossover 2
 
 
-randomGenomesReal :: Int -> [(Double,Double)] -> Rand [Genome Double]
-randomGenomesReal popsize ranges = replicateM popsize randomGenome
-    where
-      randomGenome = mapM (\varRange -> getRandomR varRange) ranges
+realUniformGenomes :: Int -> [(Double,Double)] -> [Genome Double]
+realUniformGenomes popsize ranges =
+    let dims = map (uncurry subtract) ranges :: [Double]
+        ndims = length dims :: Int
+        sd = sum dims
+        vol = product dims
+        mdim = vol ** (1.0/fromIntegral ndims) :: Double
+        msamples = (fromIntegral popsize) ** (1.0/fromIntegral ndims) :: Double
+        ptsPerDim = map (\d -> round $ d*msamples/mdim) dims :: [Int]
+        ptsInLastDims = product $ drop 1 ptsPerDim :: Int
+        ptsInFirstDim = popsize `div` ptsInLastDims :: Int
+        ptsPerDim' = ptsInFirstDim : (drop 1 ptsPerDim) :: [Int]
+        linspaces = zipWith linspace ranges ptsPerDim' :: [[Double]]
+    in  sproduct [[]] linspaces
+  where
+    linspace :: (Double, Double) -> Int -> [Double]
+    linspace (lo, hi) n = map (\i -> (fromIntegral i)*(hi-lo)/fromIntegral (n-1)) [0..n-1]
+
+    sproduct :: [[Double]] -> [[Double]] ->  [[Double]]
+    sproduct gs [] = gs
+    sproduct gs (l:ls) =
+           let gs' = [x:g | g<-gs, x<-l]
+           in  sproduct gs' ls
 
 
 data (ObjectiveFunction objectivefn a) => Solver objectivefn a = Solver {
@@ -71,7 +90,7 @@ runSolverReal :: RealProblem
               -- ^ final population and euclidean distance from the known solution
 runSolverReal problem solver = do
     let ptype = Minimizing
-    let init = randomGenomesReal (s'popsize solver) (minimizeVarRange problem)
+    let init = return $ realUniformGenomes (s'popsize solver) (minimizeVarRange problem)
     let step = nextGeneration  ptype (s'objective solver)
                (s'select solver) (s'elitesize solver)
                (s'crossover solver) (s'mutate solver)