Hello,
I don't know what is happening, but the code works fine when timeout_seconds is 8 seconds or less. But when it is longer, 'm_l': self.player.participant.vars['m_l'] and 'm_t': self.player.participant.vars['m_t'] remain constant every round.


class WP(WaitPage):
    template_name = 'sbe/WP.html'

    def vars_for_template(self):
        round_num = self.subsession.round_number
        for_margins_left = range(30, 1240 + 1, 15)
        for_margins_top = range(20, 720 + 1, 15)
        if round_num <= Constants.num_trial_rounds:
            for g in self.subsession.get_groups():
                num_dots = g.get_player_by_id(1).participant.vars['dots_displayed_trial'][(round_num - 1)]
                margins_left = random.sample(for_margins_left, num_dots)
                margins_top = random.sample(for_margins_top, num_dots)
                for p in g.get_players():
                    p.participant.vars['m_l'] = margins_left
                    p.participant.vars['m_t'] = margins_top

        else:
            for g in self.subsession.get_groups():
                num_dots = g.get_player_by_id(1).participant.vars['dots_displayed'][(round_num - Constants.num_trial_rounds - 1)]
                margins_left = random.sample(for_margins_left, num_dots)
                margins_top = random.sample(for_margins_top, num_dots)
                for p in g.get_players():
                    p.participant.vars['m_l'] = margins_left
                    p.participant.vars['m_t'] = margins_top

        return {
            'round_num': round_num,
        }


class PreDots(Page):
    timeout_seconds = 10

    def vars_for_template(self):
        round_num = self.subsession.round_number
        if round_num <= Constants.num_trial_rounds:
            self.player.num_of_dots = self.player.participant.vars['dots_displayed_trial'][(round_num - 1)]
        else:
            self.player.num_of_dots = self.player.participant.vars['dots_displayed'][(round_num - Constants.num_trial_rounds - 1)]

        return {
            'role': self.player.participant.vars['role'],
            'num_dots': self.player.num_of_dots,
            'round_num': round_num,
            'round_count': round_num - Constants.num_trial_rounds,
            'm_l': self.player.participant.vars['m_l'],
            'm_t': self.player.participant.vars['m_t']

        }

the error happens when the page sequence goes
"WP PreDots WP Prots WP PreDots" (when those are the only two pages) (and timeout_seconds = 9 or above)
if I add a third page
"WP PreDots NewPage WP Prots NewPage WP PreDots NewPage" 
then the code works fine, even if timeout_seconds is above 8

It’s recommended to do any calculations like this in after_all_players_arrive, not vars_for_template.

Is it okay to use "for g in self.subsession.get_groups():" or is it a problem to "call" all groups, given that not all of them will get to the waitpage at the same time?

Usually it doesn't make sense conceptually to do this, since why would you modify the values of groups that may be ahead or behind in the game?

I just saw that in the documentation it says
"In oTree 2.3 and earlier, after_all_players_arrive was a method, i.e. def after_all_players_arrive(self):. However, the new format is better and you should use it instead."
My requirements file says "otree>=3.4.0,<5"

I was wondering if it would be a problem if I use "def after_all_players_arrive(self):" in pages.py in the waitpage. I need a list of numbers to be random every round but equal for all players in the same group. Can I still use "def after_all_players_arrive(self):" in otree>=3.4.0,<5? Is it not recommended because the option of setting the function in "class Group(BaseGroup):" is easier or is it not recommended because I might get an error while running the experiment?

Using that syntax won’t help with your problem. Why can’t you define a group method?

At the moment it is working (I am using self.group.get_players() instead of "for g in self.subsession.get_groups():", so I am not calling all groups anymore, right?), but I was wondering if using "def after_all_players_arrive(self):" can result in some unexpected error, I am not sure why it stopped being recommended.

If I define a group method, will the random portion be executed every round? I need the numbers to change every round