Implemented Mikkelson, k66r from Axelrod's second.

axelrod/strategies/_strategies.py

@@ -11,7 +11,7 @@
     Champion, Eatherley, Tester, Gladstein, Tranquilizer, MoreGrofman,
     Kluepfel, Borufsen, Cave, WmAdams, GraaskampKatzen, Weiner, Harrington,
     MoreTidemanAndChieruzzi, Getzler, Leyvraz, White, Black, RichardHufford,
-    Yamachi, Colbert)
+    Yamachi, Colbert, Mikkelson)
 from .backstabber import BackStabber, DoubleCrosser
 from .better_and_better import BetterAndBetter
 from .bush_mosteller import BushMosteller
@@ -208,6 +208,7 @@
     NaiveProber,
     MEM2,
     Michaelos,
+    Mikkelson,
     MindBender,
     MindController,
     MindReader,

axelrod/strategies/axelrod_second.py

@@ -1851,3 +1851,67 @@ def __init__(self) -> None:
 
         super().__init__(transitions=transitions, initial_state=0,
                          initial_action=C)
+
+
+class Mikkelson(FSMPlayer):
+    """
+    Strategy submitted to Axelrod's second tournament by Ray Mikkelson (K66R)
+    and came in twentieth in that tournament.
+
+    The strategy keeps track of a variable called `credit`, which determines if
+    the strategy will Cooperate, in the sense that if `credit` is positive,
+    then the strategy Cooperates.  `credit` is initialized to 7.  After the
+    first turn, `credit` increments if the opponent Cooperated last turn, and
+    decreases by two otherwise.  `credit` is capped above by 8 and below by -7.
+    [`credit` is assessed as postive or negative, after increasing based on
+    opponent's last turn.]
+
+    If `credit` is non-positive within the first ten turns, then the strategy
+    Defects and `credit` is set to 4.  If `credit` is non-positive later, then
+    the strategy Defects if and only if (total # opponent Defections) / (turn#)
+    is at least 15%.  [Turn # starts at 1.]
+
+    Names:
+
+    - Mikkelson: [Axelrod1980b]_
+    """
+
+    name = 'Mikkelson'
+    classifier = {
+        'memory_depth': float("inf"),
+        'stochastic': False,
+        'makes_use_of': set(),
+        'long_run_time': False,
+        'inspects_source': False,
+        'manipulates_source': False,
+        'manipulates_state': False
+    }
+
+    def __init__(self) -> None:
+        super().__init__()
+        self.credit = 7
+
+    def strategy(self, opponent: Player) -> Action:
+        turn = len(self.history) + 1
+        if turn == 1:
+            return C
+
+        if opponent.history[-1] == C:
+            self.credit += 1
+            if self.credit > 8:
+                self.credit = 8
+        else:
+            self.credit -= 2
+            if self.credit < -7:
+                self.credit = -7
+
+        if turn == 2:
+            return C
+        if self.credit > 0:
+            return C
+        if turn <= 10:
+            self.credit = 4
+            return D
+        if opponent.defections / turn >= 0.15:
+            return D
+        return C

axelrod/tests/strategies/test_axelrod_second.py

@@ -1189,3 +1189,57 @@ def test_strategy(self):
         actions = [(C, C)] * 5 + [(D, C)] + [(C, C)] * 4
         actions += [(C, D)] + [(D, C), (D, C), (C, C), (C, C)] + [(C, C)]
         self.versus_test(OddBall, expected_actions=actions)
+
+
+class TestMikkelson(TestPlayer):
+    name = 'Mikkelson'
+    player = axelrod.Mikkelson
+    expected_classifier = {
+        'memory_depth': float("inf"),
+        'stochastic': False,
+        'makes_use_of': set(),
+        'long_run_time': False,
+        'inspects_source': False,
+        'manipulates_source': False,
+        'manipulates_state': False
+    }
+
+    def test_strategy(self):
+        actions = [(C, C)] * 30
+        self.versus_test(axelrod.Cooperator(), expected_actions=actions, attrs={"credit": 8})
+
+        actions = [(C, D), (C, D), (C, D), (C, D)]
+        self.versus_test(axelrod.Defector(), expected_actions=actions, attrs={"credit": 1})
+        # Defect then reset to 4
+        actions += [(D, D)]
+        self.versus_test(axelrod.Defector(), expected_actions=actions, attrs={"credit": 4})
+        # Repeat
+        actions += [(C, D), (D, D)] * 2
+        self.versus_test(axelrod.Defector(), expected_actions=actions, attrs={"credit": 4})
+        # With ten turns passed, keep defecting now
+        actions += [(C, D), (D, D)]
+        self.versus_test(axelrod.Defector(), expected_actions=actions, attrs={"credit": 0})
+        # With ten turns passed, keep defecting now
+        actions += [(D, D)] * 30
+        self.versus_test(axelrod.Defector(), expected_actions=actions, attrs={"credit": -7})
+
+
+        actions = [(C, D), (C, D), (C, C)]
+        self.versus_test(axelrod.Cycler("DDC"), expected_actions=actions, attrs={"credit": 3})
+        actions += [(C, D), (C, D)]
+        self.versus_test(axelrod.Cycler("DDC"), expected_actions=actions, attrs={"credit": 2})
+        actions += [(D, C)]
+        self.versus_test(axelrod.Cycler("DDC"), expected_actions=actions, attrs={"credit": 4})
+        actions += [(C, D)]
+        self.versus_test(axelrod.Cycler("DDC"), expected_actions=actions, attrs={"credit": 5})
+        actions += [(C, D)]
+        self.versus_test(axelrod.Cycler("DDC"), expected_actions=actions, attrs={"credit": 3})
+
+        opponent_actions = [C] * 100 + [D] * 10
+        Change_of_Heart = axelrod.MockPlayer(actions=opponent_actions)
+        actions = [(C, C)] * 100 + [(C, D)] * 4
+        self.versus_test(Change_of_Heart, expected_actions=actions, attrs={"credit": 2})
+        Change_of_Heart = axelrod.MockPlayer(actions=opponent_actions)
+        actions += [(C, D)] * 2
+        self.versus_test(Change_of_Heart, expected_actions=actions, attrs={"credit": -2})
+        # Still Cooperate, because Defect rate is low

axelrod/tests/strategies/test_meta.py

@@ -335,7 +335,7 @@ def test_strategy(self):
         self.versus_test(opponent=axelrod.Alternator(),
                          expected_actions=actions, seed=0)
 
-        actions = [(C, C), (C, D), (D, C), (C, D), (D, C)]
+        actions = [(C, C), (C, D), (C, C), (C, D), (D, C)]
         self.versus_test(opponent=axelrod.Alternator(),
                          expected_actions=actions, seed=1)