gaussiandistribution_solution.py

import math
from generaldistribution_solution import Distribution

class Gaussian(Distribution):
    """
    Gaussian distribution class for calculating and visualizing a Gaussian distribution.
    
    Attributes:
        mean (float) representing the mean value of the distribution
        stdev (float) representing the standard deviation of the distribution
        data_list (list of floats) a list of floats extracted from the data file
    """
    def __init__(self, mu=0, sigma=1):
        Distribution.__init__(self, mu, sigma)


    def calculate_mean(self):
        """
        Function to calculate the mean of the data set.
        
        Args: 
            None
        
        Returns: 
            float: Mean of the data set.
    
        """
        avg = 1.0 * sum(self.data) / len(self.data)

        self.mean = avg

        return self.mean

    def calculate_stdev(self, sample=True):
        """
        Function to calculate the standard deviation of the data set.
        
        Args: 
            sample: bool. Whether the data represents a sample or population.
        
        Returns: 
            float: Standard deviation of the data set.
    
        """

        if sample:
            n = len(self.data) - 1
        else:
            n = len(self.data)

        mean = self.calculate_mean()

        sigma = 0

        for d in self.data:
            sigma += (d - mean) ** 2

        sigma = math.sqrt(sigma / n)

        self.stdev = sigma

        return self.stdev

    def pdf(self, x):
        """
        Probability density function calculator for the gaussian distribution.
        
        Args:
            x: float. Point for calculating the probability density function.
            
        
        Returns:
            float: probability density function output.
        """

        return (1.0 / (self.stdev * math.sqrt(2 * math.pi))) * math.exp(
            -0.5 * ((x - self.mean) / self.stdev) ** 2
        )

    def __add__(self, other):
        """
		Function to add together two Gaussian distributions.
        
        Args:
            other: Gaussian. Gaussian instance.
            
        Returns:
            Gaussian: Gaussian distribution.
        """
        result = Gaussian()
        result.mean = self.mean + other.mean
        result.stdev = math.sqrt(self.stdev ** 2 + other.stdev ** 2)

        return result