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Moran processes are always stochastic #796

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Merged
merged 1 commit into from
Dec 31, 2016
Merged

Moran processes are always stochastic #796

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11 changes: 1 addition & 10 deletions axelrod/moran.py
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Original file line number Diff line number Diff line change
@@ -1,11 +1,10 @@
# -*- coding: utf-8 -*-
from collections import Counter
import random

import numpy as np

from .deterministic_cache import DeterministicCache
from .match import Match, is_stochastic
from .match import Match
from .random_ import randrange


Expand Down Expand Up @@ -94,14 +93,6 @@ def set_players(self):
self.populations = [self.population_distribution()]
self.num_players = len(self.players)

@property
def _stochastic(self):
"""
A boolean to show whether a match between two players would be
stochastic
"""
return is_stochastic(self.players, self.noise) or (self.mutation_rate > 0)

def mutate(self, index):
# If mutate, choose another strategy at random from the initial population
r = random.random()
Expand Down
19 changes: 2 additions & 17 deletions axelrod/tests/unit/test_moran.py
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Original file line number Diff line number Diff line change
@@ -1,15 +1,13 @@
# -*- coding: utf-8 -*-
from collections import Counter
import itertools
import random
import unittest

from hypothesis import given, example, settings

import axelrod
from axelrod import MoranProcess
from axelrod.moran import fitness_proportionate_selection

from hypothesis import given, example, settings

from axelrod.tests.property import strategy_lists


Expand All @@ -21,17 +19,6 @@ def test_fps(self):
self.assertEqual(fitness_proportionate_selection([1, 1, 1]), 0)
self.assertEqual(fitness_proportionate_selection([1, 1, 1]), 2)

def test_stochastic(self):
p1, p2 = axelrod.Cooperator(), axelrod.Cooperator()
mp = MoranProcess((p1, p2))
self.assertFalse(mp._stochastic)
p1, p2 = axelrod.Cooperator(), axelrod.Cooperator()
mp = MoranProcess((p1, p2), noise=0.05)
self.assertTrue(mp._stochastic)
p1, p2 = axelrod.Cooperator(), axelrod.Random()
mp = MoranProcess((p1, p2))
self.assertTrue(mp._stochastic)

def test_exit_condition(self):
p1, p2 = axelrod.Cooperator(), axelrod.Cooperator()
mp = MoranProcess((p1, p2))
Expand Down Expand Up @@ -62,7 +49,6 @@ def test_two_players_with_mutation(self):
p1, p2 = axelrod.Cooperator(), axelrod.Defector()
random.seed(5)
mp = MoranProcess((p1, p2), mutation_rate=0.2)
self.assertEqual(mp._stochastic, True)
self.assertDictEqual(mp.mutation_targets, {str(p1): [p2], str(p2): [p1]})
# Test that mutation causes the population to alternate between fixations
counters = [
Expand Down Expand Up @@ -99,7 +85,6 @@ def test_three_players_with_mutation(self):
p3 = axelrod.Defector()
players = [p1, p2, p3]
mp = MoranProcess(players, mutation_rate=0.2)
self.assertEqual(mp._stochastic, True)
self.assertDictEqual(mp.mutation_targets, {str(p1): [p3, p2], str(p2): [p1, p3], str(p3): [p1, p2]})
# Test that mutation causes the population to alternate between fixations
counters = [
Expand Down