Python script to compute regression curve.

regression_curve.py

#! /usr/local/bin/python3.6
"""
Computation of a simple linear regression curve
"""
import sys
import traceback


class RegressionCurve:
    def reg_curve(self, x, y):
        """ Regression line computation

        :param  list  x: 1st list of variables
        :param  list  y: 2nd list of variables
        :return list [a, b, c]: a-value, b-value, c-value
        """
        try:
            if type(x) != list:
                print("Argument(X) is not a list!")
                sys.exit()
            if type(y) != list:
                print("Argument(Y) is not a list!")
                sys.exit()
            if len(x) == 0:
                print("List(X) is none!")
                sys.exit()
            if len(y) == 0:
                print("List(Y) is none!")
                sys.exit()
            if len(x) != len(y):
                print("Argument list size is invalid!")
                sys.exit()
            n     = len(x)                                       # number of items
            m_x   = sum(x) / n                                   # avg(X)
            m_y   = sum(y) / n                                   # avg(Y)
            m_x2  = sum([a ** 2 for a in x]) / n                 # avg(X^2)
            m_x3  = sum([a ** 3 for a in x]) / n                 # avg(X^3)
            m_x4  = sum([a ** 4 for a in x]) / n                 # avg(X^4)
            m_xy  = sum([a * b for a, b in zip(x, y)]) / n       # avg(X * Y)
            m_x2y = sum([a * a * b for a, b in zip(x, y)]) / n   # avg(X^2 * Y)
            s_xx   = m_x2 - m_x * m_x                            # Sxx
            s_xy   = m_xy - m_x * m_y                            # Sxy
            s_xx2  = m_x3 - m_x * m_x2                           # Sxx2
            s_x2x2 = m_x4 - m_x2 * m_x2                          # Sx2x2
            s_x2y  = m_x2y - m_x2 * m_y                          # Sx2y
            b  = s_xy * s_x2x2 - s_x2y * s_xx2
            b /= s_xx * s_x2x2 - s_xx2 * s_xx2
            c  = s_x2y * s_xx - s_xy * s_xx2
            c /= s_xx * s_x2x2 - s_xx2 * s_xx2
            a = m_y - b * m_x - c * m_x2
            return [a, b, c]
        except Exception as e:
            raise


if __name__ == '__main__':
    try:
        #x = [107, 336, 233, 82, 61, 378, 129, 313, 142, 428]
        #y = [286, 851, 589, 389, 158, 1037, 463, 563, 372, 1020]
        x = [83, 71, 64, 69, 69, 64, 68, 59, 81, 91, 57, 65, 58, 62]
        y = [183, 168, 171, 178, 176, 172, 165, 158, 183, 182, 163, 175, 164, 175]
        print("説明変数 X =", x)
        print("目的変数 Y =", y)
        print("---")
        obj = RegressionCurve()
        reg_curve = obj.reg_curve(x, y)
        print("a =", reg_curve[0])
        print("b =", reg_curve[1])
        print("c =", reg_curve[2])
    except Exception as e:
        traceback.print_exc()
        sys.exit(1)