Add clone argument to Graaskamp.

Author: drvinceknight

axelrod/strategies/_strategies.py

@@ -8,7 +8,7 @@
 from .axelrod_first import (
     FirstByDavis,
     FirstByFeld,
-    Graaskamp,
+    FirstByGraaskamp,
     Grofman,
     Joss,
     Nydegger,
@@ -325,7 +325,7 @@
     GoByMajority40,
     GoByMajority5,
     Golden,
-    Graaskamp,
+    FirstByGraaskamp,
     SecondByGraaskampKatzen,
     Gradual,
     GradualKiller,

axelrod/strategies/axelrod_first.py

@@ -250,25 +250,37 @@ def strategy(self, opponent: Player) -> Action:
         return random_choice(p)
 
 
-class Graaskamp(Player):
+class FirstByGraaskamp(Player):
     """
+    Submitted to Axelrod's first tournament by James Graaskamp..
 
-    This is one of the strategies from Robert Axelrod's first tournament and is
-    described in the literature as:
+    The description written in [Axelrod1980]_ is:
+
+    > "This rule plays tit for tat for 50 moves, defects on move 51, and then
+    > plays 5 more moves of tit for tat. A check is then made to see if the player
+    > seems to be RANDOM, in which case it defects from then on. A check is also
+    > made to see if the other is TIT FOR TAT, ANALOGY (a program from the
+    > preliminary tournament), and its own twin, in which case it plays tit for
+    > tat. Otherwise it randomly defects every 5 to 15 moves, hoping that enough
+    > trust has been built up so that the other player will not notice these
+    > defections.:
+
+    This is implemented as:
 
     1. Plays Tit For Tat for the first 50 rounds;
     2. Defects on round 51;
     3. Plays 5 further rounds of Tit For Tat;
     4. A check is then made to see if the opponent is playing randomly in which
-       case it defects for the rest of the game;
+       case it defects for the rest of the game, this is implemented with a chi
+       squared test.
     5. The strategy also checks to see if the opponent is playing Tit For Tat or
-       another strategy from a preliminary tournament called ‘Analogy’  If
+       a clone of itself. If
        so it plays Tit For Tat. If not it cooperates and randomly defects every 5
        to 15 moves.
 
 
     Note that there is no information about 'Analogy' available thus Step 5 is
-    not implemented fully.
+    a "best possible" interpretation of the description in the paper.
 
     This strategy came 9th in Axelrod’s original tournament.
 
@@ -277,7 +289,7 @@ class Graaskamp(Player):
     - Graaskamp: [Axelrod1980]_
     """
 
-    name = "Graaskamp"
+    name = "First tournament by Graaskamp"
     classifier = {
         "memory_depth": float("inf"),
         "stochastic": True,
@@ -321,8 +333,8 @@ def strategy(self, opponent: Player) -> Action:
         if all(
             opponent.history[i] == self.history[i - 1]
             for i in range(1, len(self.history))
-        ):
-            # Check if opponent plays Tit for Tat
+        ) or opponent.history == self.history:
+            # Check if opponent plays Tit for Tat or a clone of itself.
             if opponent.history[-1] == D:
                 return D
             return C

axelrod/tests/strategies/test_axelrod_first.py

@@ -144,10 +144,10 @@ def test_strategy(self):
         self.versus_test(axelrod.Defector(), expected_actions=actions)
 
 
-class TestGraaskamp(TestPlayer):
+class TestFirstByGraaskamp(TestPlayer):
 
-    name = "Graaskamp: 0.05"
-    player = axelrod.Graaskamp
+    name = "First tournament by Graaskamp: 0.05"
+    player = axelrod.FirstByGraaskamp
     expected_classifier = {
         "memory_depth": float("inf"),
         "stochastic": True,

docs/reference/overview_of_strategies.rst

@@ -24,7 +24,7 @@ An indication is given as to whether or not this strategy is implemented in the
   "Stein and Rapoport", "Stein and Anatol Rapoport", ":class:`SteinAndRapoport <axelrod.strategies.axelrod_first.SteinAndRapoport>`"
   "Grudger", "James W Friedman", ":class:`Grudger <axelrod.strategies.grudger.Grudger>`"
   "Davis", "Morton Davis", ":class:`Davis <axelrod.strategies.axelrod_first.FirstByDavis>`"
-  "Graaskamp", "Jim Graaskamp", ":class:`Graaskamp <axelrod.strategies.axelrod_first.Graaskamp>`"
+  "Graaskamp", "Jim Graaskamp", ":class:`Graaskamp <axelrod.strategies.axelrod_first.FirstByGraaskamp>`"
   "Downing", "Leslie Downing", ":class:`RevisedDowning <axelrod.strategies.axelrod_first.RevisedDowning>`"
   "Feld", "Scott Feld", ":class:`Feld <axelrod.strategies.axelrod_first.FirstByFeld>`"
   "Joss", "Johann Joss", ":class:`Joss <axelrod.strategies.axelrod_first.Joss>`"