In [8]:

    

from random import randint

class CoinTossTrials(object):
    def __init__(self, n_flips, n_trials, coins_weighted, weight_heads):
        """
        Arguments:
        n_flips: the number of flips to perform in a trial
        n_trials: the number of trials to perform in the experiment
        coins_weighted: the percent of trials to use weighted coins
        weight_heads: the probability that a weighted coin will turn up heads
        """
        self.n_flips = n_flips
        self.n_trials = n_trials
        self.weight_heads = weight_heads
        self.coins_weighted = coins_weighted
        
    def fair_coin_toss(self):
        """
        Function to simulate a single fair coin toss
        """
        flip = randint(1,2)
        if flip == 1:
            return 'heads'
        else:
            return 'tails'

    def weighted_coin_toss(self):
        """
        Function to simulate a single weighted coin toss
        """
        ## Establish percentenge of heads and tails for weighted coin
        percent_heads = self.weight_heads
        percent_tails = 100-percent_heads

        ## Use the probabilities to weight the coutcome
        pull_heads = randint(1, percent_heads)
        pull_tails = randint(1, percent_tails)

        if pull_heads < pull_tails:
            return 'tails'
        else:
            return 'heads'
    
    def flip_trial(self, trial_type):
        """
        Function to carry out a trial flipping n_flips times
        """
        flips_heads = 0
        flips_tails = 0
        for i in range(self.n_flips):
            if trial_type == 'fair':
                coin_toss = self.fair_coin_toss()
            if trial_type == 'weighted':
                coin_toss = self.weighted_coin_toss()

            if coin_toss == 'heads':
                flips_heads += 1

        return flips_heads

    def population_trial_distributions(self):
        """
        Function to carry n_trials 
        
        Returns:
        weighted_trials_distributions: a list where each element is the number of heads 
            that came up in a simulated trial using a weighted coin. 
        fair_trials_distributinos: a list where each element is the number of heads that
            came up in a simulated trial using a fair coin.
        """
        weighted_trials_distributions = []
        fair_trials_distributions = []
        n_weighted_trials = (float(self.coins_weighted))*self.n_trials

        for n in range(self.n_trials):
            if n < n_weighted_trials:
                weighted_trial_heads = self.flip_trial('weighted')
                weighted_trials_distributions.append(weighted_trial_heads)

            else:
                fair_trial_heads = self.flip_trial('fair')
                fair_trials_distributions.append(fair_trial_heads)

        return weighted_trials_distributions, fair_trials_distributions