from axelrod.action import Action
from axelrod.player import Player
C, D = Action.C, Action.D
[docs]class Grumpy(Player):
"""
A player that defects after a certain level of grumpiness.
Grumpiness increases when the opponent defects and decreases
when the opponent co-operates.
Names:
- Grumpy: Original name by Jason Young
"""
name = "Grumpy"
classifier = {
"memory_depth": float("inf"), # Long memory
"stochastic": False,
"long_run_time": False,
"inspects_source": False,
"manipulates_source": False,
"manipulates_state": False,
}
def __init__(
self,
starting_state: str = "Nice",
grumpy_threshold: int = 10,
nice_threshold: int = -10,
) -> None:
"""
Parameters
----------
starting_state: str
'Nice' or 'Grumpy'
grumpy_threshold: int
The threshold of opponent defections - cooperations to become
grumpy
nice_threshold: int
The threshold of opponent defections - cooperations to become
nice
"""
super().__init__()
self.state = starting_state
self.grumpy_threshold = grumpy_threshold
self.nice_threshold = nice_threshold
[docs] def strategy(self, opponent: Player) -> Action:
"""A player that gets grumpier the more the opposition defects,
and nicer the more they cooperate.
Starts off Nice, but becomes grumpy once the grumpiness threshold is
hit. Won't become nice once that grumpy threshold is hit, but must
reach a much lower threshold before it becomes nice again.
"""
grumpiness = opponent.defections - opponent.cooperations
if self.state == "Nice":
if grumpiness > self.grumpy_threshold:
self.state = "Grumpy"
return D
return C
if self.state == "Grumpy":
if grumpiness < self.nice_threshold:
self.state = "Nice"
return C
return D