implement mutateGenomeRemoveGene

2 files changed, 39 insertions, 2 deletions

diff --git a/src/Genome.hs b/src/Genome.hs
index 927005e..e0091b9 100644
--- a/src/Genome.hs
+++ b/src/Genome.hs
@@ -9,6 +9,7 @@ module Genome
   , mutateGenomeAddInternal
   , mutateGenomeRemoveInternal
   , mutateGenomeAddGene 
+  , mutateGenomeRemoveGene 
   ) where
 
 
@@ -149,8 +150,6 @@ mutateGenomeAddGene g r =
     gene = Gene so si w
   in (g {genes = gene:(genes g)}, r''')
 
-    
-
 randomSource :: RandomGen a => Genome -> a -> (NeuronIndex, a)
 randomSource g r =
   let
@@ -164,3 +163,12 @@ randomSink g r =
     (idx, r') = randomR (0, numInternal g + numOutput g - 1) r
     result = if idx < numInternal g then Internal idx else Output $ idx - numInput g
   in (result, r')
+
+
+-- remove a random gene
+mutateGenomeRemoveGene :: RandomGen a => Genome -> a -> (Genome, a)
+mutateGenomeRemoveGene g r =
+  let
+    (idx, r') = randomR (0, (length $ genes g) - 1) r
+    (front, _:back) = splitAt idx (genes g)
+  in (g {genes = front ++ back}, r')
diff --git a/test/GenomeTest.hs b/test/GenomeTest.hs
index d775467..aa6d310 100644
--- a/test/GenomeTest.hs
+++ b/test/GenomeTest.hs
@@ -175,4 +175,33 @@ mutationTests = testGroup "mutations" $
       validSource (source new) @?= True
       validSink (sink new) @?= True
       (w >= -4) && (w <= 4) @?= True
+  , testCase "remove a gene" $
+    let
+      r = mkStdGen 1 -- randomR (0, 2) produces (1, 2, 0, ...)
+      genome = Genome 
+        { numInput = 1
+        , numInternal = 3
+        , numOutput = 1
+        , genes =
+          [ Gene { source = Input 0, sink = Internal 0, weight = 1.0 }
+          , Gene { source = Internal 0, sink = Internal 1, weight = 1.0 }
+          , Gene { source = Internal 2, sink = Output 0, weight = 1.0 }
+          ]
+        }
+      (genome', r') = mutateGenomeRemoveGene genome r
+      (genome'', r'') = mutateGenomeRemoveGene genome r'
+      (genome''', _) = mutateGenomeRemoveGene genome r''
+    in do
+      genes genome' @?= 
+        [ Gene { source = Input 0, sink = Internal 0, weight = 1.0 }
+        , Gene { source = Internal 2, sink = Output 0, weight = 1.0 }
+        ]
+      genes genome'' @?=
+        [ Gene { source = Input 0, sink = Internal 0, weight = 1.0 }
+        , Gene { source = Internal 0, sink = Internal 1, weight = 1.0 }
+        ]
+      genes genome''' @?=
+        [ Gene { source = Internal 0, sink = Internal 1, weight = 1.0 }
+        , Gene { source = Internal 2, sink = Output 0, weight = 1.0 }
+        ]
   ]