from otree.api import ( models, widgets, BaseConstants, BaseSubsession, BaseGroup, BasePlayer, Currency as c, currency_range ) import random doc = """ A demo of how rounds work in oTree, in the context of 'matching pennies' """ class Constants(BaseConstants): name_in_url = 'matching_pennies' players_per_group = 2 num_rounds = 4 stakes = c(100) class Subsession(BaseSubsession): def creating_session(self): if self.round_number == 1: paying_round = random.randint(1, Constants.num_rounds) self.session.vars['paying_round'] = paying_round if self.round_number == 3: # reverse the roles matrix = self.get_group_matrix() for row in matrix: row.reverse() self.set_group_matrix(matrix) if self.round_number > 3: self.group_like_round(3) class Group(BaseGroup): def set_payoffs(self): matcher = self.get_player_by_role('Matcher') mismatcher = self.get_player_by_role('Mismatcher') if matcher.penny_side == mismatcher.penny_side: matcher.is_winner = True mismatcher.is_winner = False else: matcher.is_winner = False mismatcher.is_winner = True for player in [mismatcher, matcher]: if self.subsession.round_number == self.session.vars['paying_round'] and player.is_winner: player.payoff = Constants.stakes else: player.payoff = c(0) class Player(BasePlayer): penny_side = models.StringField( choices=['Heads', 'Tails'], widget=widgets.RadioSelect ) is_winner = models.BooleanField() def role(self): if self.id_in_group == 1: return 'Mismatcher' if self.id_in_group == 2: return 'Matcher'