def maybe_update_output(self) -> bool:
try:
full_output = evaluate(self.input)
self.output = float(round(full_output, 10))
return True
except EvaluatorError:
self.output = "Math Error"
return False
def evaluate_fitness(chromosome, target):
'''evaluates and sets the fitness.
Returns _False_ if this is a solution(fitness was _NOT_ evaluated).
Returns _True_ if not a solution(Fitness _WAS_ evaluated).
'''
changed = False
decoded = decode(chromosome, symbolize_ops=True)
# We have to look for a possible divide by zero error.
# We look for such a pattern(a '/' followed by a 0) and then replace
# the '/' with a '+'. This should prevent the Exception at runtime
# without affecting the evolution of the chromosome.
for i in xrange(len(decoded) - 1):
if decoded[i] == '/' and decoded[i+1] == 0:
changed = True
decoded[i] = '+'
# Remove trailing operators, as they obviously are meaningless.
while decoded[-1] in OPERATORS:
changed = True
decoded.pop()
# Reflect the changes in the chromosome.
if changed:
chromosome.bits = encode(decoded)
try:
val = expr.evaluate(decoded)
except ZeroDivisionError:
val = 99999 # A large value, making the fitness very bad.
if val == target:
return False
fitness = 1.0 / abs(target - val)
chromosome.fitness = fitness
return True
def evaluate_fitness(chromosome, target):
'''evaluates and sets the fitness.
Returns _False_ if this is a solution(fitness was _NOT_ evaluated).
Returns _True_ if not a solution(Fitness _WAS_ evaluated).
'''
changed = False
decoded = decode(chromosome, symbolize_ops=True)
# We have to look for a possible divide by zero error.
# We look for such a pattern(a '/' followed by a 0) and then replace
# the '/' with a '+'. This should prevent the Exception at runtime
# without affecting the evolution of the chromosome.
for i in xrange(len(decoded) - 1):
if decoded[i] == '/' and decoded[i + 1] == 0:
changed = True
decoded[i] = '+'
# Remove trailing operators, as they obviously are meaningless.
while decoded[-1] in OPERATORS:
changed = True
decoded.pop()
# Reflect the changes in the chromosome.
if changed:
chromosome.bits = encode(decoded)
try:
val = expr.evaluate(decoded)
except ZeroDivisionError:
val = 99999 # A large value, making the fitness very bad.
if val == target:
return False
fitness = 1.0 / abs(target - val)
chromosome.fitness = fitness
return True
def test_evaluate_or(self):
self.assertEqual(expr.evaluate(expr.parse('a|b|c'), {'a': True}),
expr.parse('1'))
self.assertEqual(expr.evaluate(expr.parse('a|b|c'), {'a': False}),
expr.parse('b|c'))
def test_evaluate_and(self):
self.assertEqual(expr.evaluate(expr.parse('a&b&c'), {'a': True}),
expr.parse('b&c'))
self.assertEqual(expr.evaluate(expr.parse('a&b&c'), {'a': False}),
expr.parse('0'))
def test_evaluate_negated(self):
self.assertEqual(expr.evaluate(expr.parse('~a'), {'a': True}), False)
self.assertEqual(expr.evaluate(expr.parse('~a'), {'a': False}), True)
def test_evaluate_simple(self):
self.assertEqual(expr.evaluate(expr.parse('a'), {'a': True}), True)
self.assertEqual(expr.evaluate(expr.parse('a'), {'a': False}), False)
def test_evaluate_constant(self):
self.assertEqual(expr.evaluate(expr.parse('0'), {'a': True}), False)
self.assertEqual(expr.evaluate(expr.parse('1'), {'a': True}), True)