Implemented Colbert, K51R 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)
+    Yamachi, Colbert)
 from .backstabber import BackStabber, DoubleCrosser
 from .better_and_better import BetterAndBetter
 from .bush_mosteller import BushMosteller
@@ -118,6 +118,7 @@
     CautiousQLearner,
     Cave,
     Champion,
+    Colbert,
     CollectiveStrategy,
     ContriteTitForTat,
     Cooperator,

axelrod/strategies/axelrod_second.py

@@ -9,6 +9,7 @@
 from axelrod.action import Action
 from axelrod.player import Player
 from axelrod.random_ import random_choice
+from axelrod.strategies.finite_state_machines import FSMPlayer
 
 from axelrod.interaction_utils import compute_final_score
 
@@ -1803,3 +1804,50 @@ def strategy(self, opponent: Player) -> Action:
            self.count_them_us_them[(them_two_ago, us_last, D)]:
             return self.try_return(C, opponent.defections)
         return self.try_return(D, opponent.defections)
+
+
+class Colbert(FSMPlayer):
+    """
+    Strategy submitted to Axelrod's second tournament by William Colbert (K51R)
+    and came in eighteenth in that tournament.
+
+    In the first eight turns, this strategy Coopearates on all but the sixth
+    turn, in which it Defects.  After that, the strategy responds to an
+    opponent Cooperation with a single Cooperation, and responds to a Defection
+    with a chain of responses:  Defect, Defect, Cooperate, Cooperate.  During
+    this chain, the strategy ignores opponent's moves.
+
+    Names:
+
+    - Colbert: [Axelrod1980b]_
+    """
+
+    name = "Colbert"
+    classifier = {
+        'memory_depth': 4,
+        'stochastic': False,
+        'makes_use_of': set(),
+        'long_run_time': False,
+        'inspects_source': False,
+        'manipulates_source': False,
+        'manipulates_state': False
+    }
+
+    def __init__(self) -> None:
+        transitions = (
+            (0, C, 1, C), (0, D, 1, C),  # First 8 turns are special
+            (1, C, 2, C), (1, D, 2, C),
+            (2, C, 3, C), (2, D, 3, C),
+            (3, C, 4, C), (3, D, 4, C),
+            (4, C, 5, D), (4, D, 5, D),  # Defect on 6th turn.
+            (5, C, 6, C), (5, D, 6, C),
+            (6, C, 7, C), (6, D, 7, C),
+
+            (7, C, 7, C), (7, D, 8, D),
+            (8, C, 9, D), (8, D, 9, D),
+            (9, C, 10, C), (9, D, 10, C),
+            (10, C, 7, C), (10, D, 7, C)
+        )
+
+        super().__init__(transitions=transitions, initial_state=0,
+                         initial_action=C)

axelrod/tests/strategies/test_axelrod_second.py

@@ -1161,3 +1161,31 @@ def test_strategy(self):
         actions += [(D, D)]  # Next turn, `portion_defect` = 0.5521
         actions += [(D, D), (C, D), (D, C), (C, D)]  # Takes a turn to fall back into the cycle.
         self.versus_test(axelrod.Ripoff(), expected_actions=actions)
+
+
+class TestColbert(TestPlayer):
+    name = 'Colbert'
+    player = axelrod.Colbert
+    expected_classifier = {
+        'memory_depth': 4,
+        '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)] * 5 + [(D, C)] + [(C, C)] * 30
+        self.versus_test(axelrod.Cooperator(), expected_actions=actions)
+
+        actions = [(C, D)] * 5 + [(D, D)] + [(C, D)] * 2
+        actions += [(D, D), (D, D), (C, D), (C, D)] * 20
+        self.versus_test(axelrod.Defector(), expected_actions=actions)
+
+        opponent_actions = [C] * 8 + [C, C, D, C, C, C, C, C]
+        OddBall = axelrod.MockPlayer(actions=opponent_actions)
+        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)

docs/tutorials/advanced/classification_of_strategies.rst

@@ -69,7 +69,7 @@ range of memory_depth values, we can use the 'min_memory_depth' and
     ... }
     >>> strategies = axl.filtered_strategies(filterset)
     >>> len(strategies)
-    56
+    57
 
 We can also identify strategies that make use of particular properties of the
 tournament. For example, here is the number of strategies that  make use of the