prisoner/__init__.py

from otree.api import *


doc = """
This is a one-shot "Prisoner's Dilemma". Two players are asked separately
whether they want to cooperate or defect. Their choices directly determine the
payoffs.
"""


class C(BaseConstants):
    NAME_IN_URL = 'prisoner'
    PLAYERS_PER_GROUP = 2
    NUM_ROUNDS = 1
    PAYOFF_A = cu(300)
    PAYOFF_B = cu(200)
    PAYOFF_C = cu(100)
    PAYOFF_D = cu(0)


class Subsession(BaseSubsession):
    pass


class Group(BaseGroup):
    pass


class Player(BasePlayer):
    cooperate = models.BooleanField(
        choices=[[True, 'Choice A'], [False, 'Choice B']],
        doc="""This player's decision (labels neutralized)""",
        widget=widgets.RadioSelect,
    )


# FUNCTIONS
def set_payoffs(group: Group):
    for p in group.get_players():
        set_payoff(p)


def other_player(player: Player):
    return player.get_others_in_group()[0]


def set_payoff(player: Player):
    payoff_matrix = {
        (False, True): C.PAYOFF_A,
        (True, True): C.PAYOFF_B,
        (False, False): C.PAYOFF_C,
        (True, False): C.PAYOFF_D,
    }
    other = other_player(player)
    player.payoff = payoff_matrix[(player.cooperate, other.cooperate)]


# PAGES
class Introduction(Page):
    @staticmethod
    def get_timeout_seconds(player: Player):
        # Allow session config override; default to 100 seconds
        return player.session.config.get('prisoner_intro_timeout', 100)


class Decision(Page):
    form_model = 'player'
    form_fields = ['cooperate']


class ResultsWaitPage(WaitPage):
    after_all_players_arrive = set_payoffs


class Results(Page):
    @staticmethod
    def vars_for_template(player: Player):
        opponent = other_player(player)
        return dict(
            opponent=opponent,
            same_choice=player.cooperate == opponent.cooperate,
            my_decision=player.field_display('cooperate'),
            opponent_decision=opponent.field_display('cooperate'),
        )


page_sequence = [Introduction, Decision, ResultsWaitPage, Results]