SpitefulCC from [Mathieu2015]

axelrod/strategies/_strategies.py

@@ -142,6 +142,7 @@
     GrudgerAlternator,
     OppositeGrudger,
     SoftGrudger,
+    SpitefulCC,
 )
 from .grumpy import Grumpy
 from .handshake import Handshake
@@ -467,6 +468,7 @@
     SolutionB1,
     SolutionB5,
     SpitefulTitForTat,
+    SpitefulCC,
     Stalker,
     StochasticCooperator,
     StochasticWSLS,

axelrod/strategies/grudger.py

@@ -24,7 +24,7 @@ class Grudger(Player):
 
     name = "Grudger"
     classifier = {
-        "memory_depth": float('inf'),
+        "memory_depth": float("inf"),
         "stochastic": False,
         "long_run_time": False,
         "inspects_source": False,
@@ -310,3 +310,35 @@ def strategy(self, opponent: Player) -> Action:
 
     def __repr__(self) -> str:
         return "%s: n=%s,d=%s,c=%s" % (self.name, self.n, self.d, self.c)
+
+
+class SpitefulCC(Player):
+    """
+    Behaves like Grudger after cooperating for 2 turns
+
+    Names:
+
+    - spiteful_cc: [Mathieu2015]_
+    """
+
+    name = "SpitefulCC"
+    classifier = {
+        "memory_depth": float("inf"),  # Long memory
+        "stochastic": False,
+        "long_run_time": False,
+        "inspects_source": False,
+        "manipulates_source": False,
+        "manipulates_state": False,
+    }
+
+    @staticmethod
+    def strategy(opponent: Player) -> Action:
+        """
+        Cooperates until the oponent defects, then defects forever.
+        Always cooperates twice at the start.
+        """
+        if len(opponent.history) < 2:
+            return C
+        elif opponent.defections:
+            return D
+        return C

axelrod/tests/strategies/test_grudger.py

@@ -12,7 +12,7 @@ class TestGrudger(TestPlayer):
     name = "Grudger"
     player = axl.Grudger
     expected_classifier = {
-        "memory_depth": float('inf'),
+        "memory_depth": float("inf"),
         "stochastic": False,
         "makes_use_of": set(),
         "long_run_time": False,
@@ -276,3 +276,34 @@ def test_strategy(self):
             expected_actions=actions,
             init_kwargs={"n": 1, "d": 1, "c": 1},
         )
+
+
+class TestSpitefulCC(TestPlayer):
+
+    name = "SpitefulCC"
+    player = axl.SpitefulCC
+    expected_classifier = {
+        "memory_depth": float("inf"),  # Long memory
+        "stochastic": False,
+        "makes_use_of": set(),
+        "long_run_time": False,
+        "inspects_source": False,
+        "manipulates_source": False,
+        "manipulates_state": False,
+    }
+
+    def test_strategy(self):
+        # If opponent defects at any point then the player will defect forever.
+        # Cooperates for the first 2 turns.
+        opponent = axl.Cooperator()
+        actions = [(C, C)] * 20
+        self.versus_test(opponent, expected_actions=actions)
+
+        opponent = axl.Defector()
+        actions = [(C, D)] * 2 + [(D, D)] * 20
+        self.versus_test(opponent, expected_actions=actions)
+
+        opponent_actions = [D] * 20 + [C] * 20
+        opponent = axl.MockPlayer(actions=opponent_actions)
+        actions = [(C, D)] * 2 + [(D, D)] * 18 + [(D, C)] * 20
+        self.versus_test(opponent, expected_actions=actions)

axelrod/tests/strategies/test_meta.py

@@ -638,7 +638,7 @@ def classifier_test(self, expected_class_classifier=None):
         pass
 
     def test_strategy(self):
-        actions = [(C, C), (C, D), (D, C), (D, D), (D, C)]
+        actions = [(C, C), (C, D), (C, C), (D, D), (D, C)]
         self.versus_test(opponent=axl.Alternator(), expected_actions=actions, seed=11)
 
 

docs/index.rst

@@ -53,7 +53,7 @@ Count the number of available players::
 
     >>> import axelrod as axl
     >>> len(axl.strategies)
-    236
+    237
 
 Create matches between two players::
 
@@ -111,4 +111,3 @@ Indices and tables
 * :ref:`genindex`
 * :ref:`modindex`
 * :ref:`search`
-