add freqAnalyzer strategy

axelrod/strategies/_strategies.py

@@ -238,6 +238,7 @@
 )
 from .shortmem import ShortMem
 from .stalker import Stalker
+from .frequency_analyzer import FrequencyAnalyzer
 from .titfortat import (
     AdaptiveTitForTat,
     Alexei,
@@ -366,6 +367,7 @@
     ForgivingTitForTat,
     Fortress3,
     Fortress4,
+    FrequencyAnalyzer,
     GTFT,
     GeneralSoftGrudger,
     GoByMajority,

axelrod/strategies/frequency_analyzer.py

@@ -0,0 +1,109 @@
+from axelrod.action import Action, actions_to_str
+from axelrod.player import Player
+from axelrod.strategy_transformers import (
+    FinalTransformer,
+    TrackHistoryTransformer,
+)
+
+C, D = Action.C, Action.D
+
+
+class FrequencyAnalyzer(Player):
+    """
+    A player starts by playing TitForTat for the first 30 turns (dataset generation phase).
+
+    Take the matrix of last 2 moves by both Player and Opponent.
+
+    While in dataset generation phase, construct a dictionary d, where keys are each 4 move sequence
+    and the corresponding value for each key is a list of the subsequent Opponent move. The 4 move sequence
+    starts with the Opponent move.
+
+    For example, if a game at turn 5 looks like this:
+
+    Opp:    C, C, D, C, D
+    Player: C, C, C, D, C
+
+    d should look like this:
+
+    { [CCCC]: [D],
+      [CCDC]: [C],
+      [DCCD]: [D] }
+
+    During dataset generation phase, Player will play TitForTat. After end of dataset generation phase,
+    Player will switch strategies. Upon encountering a particular 4-move sequence in the game, Player will look up history
+    of subsequent Opponent move. If ratio of defections to total moves exceeds p, Player will defect. Otherwise,
+    Player will cooperate.
+
+    Could fall under "Hunter" class of strategies.
+    More likely falls under LookerUp class of strategies.
+
+    Names:
+
+    - FrequencyAnalyzer (FREQ): Original by Ian Miller
+    """
+
+    # These are various properties for the strategy
+    name = "FrequencyAnalyzer"
+    classifier = {
+        "memory_depth": float("inf"),
+        "stochastic": False,
+        "long_run_time": False,
+        "inspects_source": False,
+        "manipulates_source": False,
+        "manipulates_state": False,
+    }
+
+    def __init__(self) -> None:
+        """
+        Parameters
+        ----------
+        p, float
+            The probability to cooperate
+        """
+        super().__init__()
+        self.minimum_cooperation_ratio = 0.25
+        self.frequency_table = dict()
+        self.last_sequence = ""
+        self.current_sequence = ""
+
+    def strategy(self, opponent: Player) -> Action:
+        """This is the actual strategy"""
+        if len(self.history) > 5:
+            self.last_sequence = (
+                str(opponent.history[-3])
+                + str(self.history[-3])
+                + str(opponent.history[-2])
+                + str(self.history[-2])
+            )
+            self.current_sequence = (
+                str(opponent.history[-2])
+                + str(self.history[-2])
+                + str(opponent.history[-1])
+                + str(self.history[-1])
+            )
+            self.update_table(opponent)
+
+        # dataset generation phase
+        if (len(self.history) < 30) or (
+            self.current_sequence not in self.frequency_table
+        ):
+            if not self.history:
+                return C
+            if opponent.history[-1] == D:
+                return D
+            return C
+
+        # post-dataset generation phase
+        results = self.frequency_table[self.current_sequence]
+        cooperates = results.count(C)
+        if (cooperates / len(self.history)) > self.minimum_cooperation_ratio:
+            return C
+        return D
+
+    def update_table(self, opponent: Player):
+        if self.last_sequence in self.frequency_table.keys():
+            results = self.frequency_table[self.last_sequence]
+            results.append(opponent.history[-1])
+            self.frequency_table[self.last_sequence] = results
+        else:
+            self.frequency_table[self.last_sequence] = [opponent.history[-1]]

axelrod/tests/strategies/test_frequency_analyzer.py

@@ -0,0 +1,159 @@
+"""Tests for the FrequencyAnalyzer strategy."""
+
+import axelrod as axl
+
+from .test_player import TestPlayer
+
+C, D = axl.Action.C, axl.Action.D
+
+
+class Test(TestPlayer):
+
+    name = "FrequencyAnalyzer"
+    player = axl.FrequencyAnalyzer
+    expected_classifier = {
+        "memory_depth": float("inf"),
+        "stochastic": False,
+        "long_run_time": False,
+        "makes_use_of": set(),
+        "inspects_source": False,
+        "manipulates_source": False,
+        "manipulates_state": False,
+    }
+
+    def test_strategy_early(self):
+        # Test games that end while still in dataset generation phase (<30 turns)
+        opponent_actions = [C, C, D, C, D]
+        expected = [(C, C), (C, C), (C, D), (D, C), (C, D)]
+        self.versus_test(
+            axl.MockPlayer(opponent_actions), expected_actions=expected, seed=4
+        )
+
+    def test_strategy_defector(self):
+        # Test against all defections
+        opponent_actions = [D] * 30
+        expected = [(C, D)] + [(D, D)] * 29
+        self.versus_test(
+            axl.MockPlayer(opponent_actions), expected_actions=expected, seed=4
+        )
+
+    def test_strategy_cooperator(self):
+        # Test games that end while still in dataset generation phase (<30 turns)
+        opponent_actions = [C] * 30
+        expected = [(C, C)] * 30
+        self.versus_test(
+            axl.MockPlayer(opponent_actions), expected_actions=expected, seed=4
+        )
+
+    def test_strategy_random(self):
+        # Test of 50 turns against random strategy
+        opponent_actions = [
+            C,
+            D,
+            D,
+            D,
+            D,
+            D,
+            D,
+            C,
+            D,
+            C,
+            D,
+            C,
+            D,
+            C,
+            D,
+            D,
+            C,
+            D,
+            C,
+            D,
+            D,
+            C,
+            D,
+            D,
+            D,
+            D,
+            D,
+            C,
+            C,
+            D,
+            D,
+            C,
+            C,
+            C,
+            D,
+            D,
+            C,
+            D,
+            C,
+            C,
+            C,
+            D,
+            D,
+            C,
+            C,
+            C,
+            D,
+            C,
+            D,
+            D,
+        ]
+        expected = [
+            (C, C),
+            (C, D),
+            (D, D),
+            (D, D),
+            (D, D),
+            (D, D),
+            (D, D),
+            (D, C),
+            (C, D),
+            (D, C),
+            (C, D),
+            (D, C),
+            (C, D),
+            (D, C),
+            (C, D),
+            (D, D),
+            (D, C),
+            (C, D),
+            (D, C),
+            (C, D),
+            (D, D),
+            (D, C),
+            (C, D),
+            (D, D),
+            (D, D),
+            (D, D),
+            (D, D),
+            (D, C),
+            (C, C),
+            (C, D),  # rd 30 (end of dataset generation phase)
+            (D, D),
+            (D, C),
+            (
+                D,
+                C,
+            ),  # example of non TFT (by this point, FrequencyAnalyzer is generally distrustful of opponent)
+            (C, C),
+            (D, D),
+            (D, D),
+            (D, C),
+            (D, D),
+            (D, C),
+            (D, C),
+            (D, C),
+            (D, D),
+            (D, D),
+            (D, C),
+            (D, C),
+            (D, C),
+            (D, D),
+            (D, C),
+            (D, D),
+            (D, D),
+        ]
+        self.versus_test(
+            axl.MockPlayer(opponent_actions), expected_actions=expected, seed=4
+        )

docs/index.rst

@@ -53,7 +53,7 @@ Count the number of available players::
 
     >>> import axelrod as axl
     >>> len(axl.strategies)
-    240
+    241
 
 Create matches between two players::
 

docs/reference/strategy_index.rst

@@ -48,6 +48,8 @@ Here are the docstrings of all the strategies in the library.
    :members:
 .. automodule:: axelrod.strategies.forgiver
    :members:
+.. automodule:: axelrod.strategies.frequency_analyzer
+   :members:
 .. automodule:: axelrod.strategies.gambler
    :members:
 .. automodule:: axelrod.strategies.gobymajority

run_mypy.py

@@ -31,6 +31,7 @@
     "axelrod/strategies/darwin.py",
     "axelrod/strategies/defector.py",
     "axelrod/strategies/forgiver.py",
+    "axelrod/strategies/frequency_analyzer.py",
     "axelrod/strategies/gradualkiller.py",
     "axelrod/strategies/grudger.py",
     "axelrod/strategies/grumpy.py",