Add decimal individual support for flip bit mutation operator.

PytLab · Dec 13, 2017 · 7168dc0 · 7168dc0
1 parent f6b2ef0
commit 7168dc0
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Showing 2 changed files with 29 additions and 5 deletions.
diff --git a/gaft/operators/mutation/flip_bit_mutation.py b/gaft/operators/mutation/flip_bit_mutation.py
@@ -3,10 +3,12 @@
 
 ''' Flip Bit mutation implementation. '''
 
-from random import random
+from random import random, uniform
 
 from ...mpiutil import mpi
 from ...plugin_interfaces.operators.mutation import Mutation
+from ...components.binary_individual import BinaryIndividual
+from ...components.decimal_individual import DecimalIndividual
 
 
 class FlipBitMutation(Mutation):
@@ -30,9 +32,20 @@ def mutate(self, individual, engine):
 
         if do_mutation:
             for i, genome in enumerate(individual.chromsome):
-                do_flip = True if random() <= self.pm else False
-                if do_flip:
+                no_flip = True if random() > self.pm else False
+                if no_flip:
+                    continue
+
+                if type(individual) is BinaryIndividual:
                     individual.chromsome[i] = genome^1
+                elif type(individual) is DecimalIndividual:
+                    a, b = individual.ranges[i]
+                    eps = individual.precisions[i]
+                    n_intervals = (b - a)//eps
+                    n = int(uniform(0, n_intervals + 1))
+                    individual.chromsome[i] = a + n*eps
+                else:
+                    raise TypeError('Wrong individual type: {}'.format(type(individual)))
 
             # Update solution.
             individual.solution = individual.decode()

diff --git a/tests/flip_bit_mutation_test.py b/tests/flip_bit_mutation_test.py
@@ -6,15 +6,15 @@
 
 import unittest
 
-from gaft.components import BinaryIndividual
+from gaft.components import BinaryIndividual, DecimalIndividual
 from gaft.operators.mutation.flip_bit_mutation import FlipBitMutation
 
 class FlipBitMutationTest(unittest.TestCase):
 
     def setUp(self):
         self.maxDiff
 
-    def test_mutate(self):
+    def test_mutate_binary_indv(self):
         ''' Make sure the individual can be mutated correctly.
         '''
         indv = BinaryIndividual(ranges=[(0, 1)], verbosity=0).init(solution=[0.398])
@@ -25,6 +25,17 @@ def test_mutate(self):
         mutation.mutate(indv, engine=None)
         self.assertListEqual(indv.chromsome, chromsome_after)
 
+    def test_mutate_decimal_indv(self):
+        ''' Make sure individual with decimal encoding can be mutated correctly.
+        '''
+        indv = DecimalIndividual(ranges=[(0, 1), (0, 2)]).init(solution=[0.5, 1.5])
+        mutation = FlipBitMutation(pm=1.0)
+        chromsome_before = [0.5, 1.5]
+        self.assertListEqual(indv.chromsome, chromsome_before)
+        mutation.mutate(indv, engine=None)
+        for a, b in zip(indv.chromsome, chromsome_before):
+            self.assertNotEqual(a, b)
+
 if '__main__' == __name__:
     suite = unittest.TestLoader().loadTestsFromTestCase(FlipBitMutationTest)
     unittest.TextTestRunner(verbosity=2).run(suite)