Python - 数値データファイルからデータを読み込み重回帰線を求める。

以下のようなタブ区切りの数値データ系列ファイルからデータを読み込み重回帰線を求めるプログラム。
1行目：目的変数(y)
2行目：説明変数1(x1)
3行目：説明変数2(x2)

MultipleRegressionAnalysis_Data1.txt

65.7    67.8    70.3    72.0    74.3    76.2
3.27    3.06    4.22    4.10    5.26    6.18
69.7    69.7    71.3    77.6    81.0    78.7

MultipleRegressionAnalysis_2.py

from matplotlib import pyplot as plt
import numpy as np
from mpl_toolkits.mplot3d import Axes3D 

def load_data(filename):
    with open(filename) as lines:
        return [[float(data) for data in line.strip().split('\t')]
                for line in lines]

def calc_average(data):
    return sum(data) / len(data)

def calc_sum_of_square(data_list):
    ave = calc_average(data_list)
    return sum((d - ave)**2 for data in data_list)

def calc_sum_of_square(data_list1, data_list2):
    ave1 = calc_average(data_list1)
    ave2 = calc_average(data_list2)
    return sum((data1 * data2 - ave1 * ave2)**2 for data1, data2 in zip(data_list1, data_list2))

if __name__ == "__main__":
    data = load_data('MultipleRegressionAnalysis_Data1.txt')
    s = [[calc_sum_of_square(data1, data2) for data2 in data]
            for data1 in data]

    det = s[1][1]*s[2][2] - s[1][2]**2
    # 偏回帰係数計算
    b1 = (s[0][1]*s[2][2] - s[0][2]*s[1][2])/det
    b2 = (s[0][2]*s[1][1] - s[0][1]*s[1][2])/det
    b0 = calc_average(data[0]) - b1*calc_average(data[1]) - b2*calc_average(data[2])
    # 重回帰式表示
    print("Y = " + str(b1) + " x1 + " + str(b2) + " x2 + " + str(b0))

    fig = plt.figure()
    ax = Axes3D(fig)
    # 求めた重回帰式から平面表示
    x1 = np.arange(0, 10, 0.25)
    x2 = np.arange(65, 80, 0.25)
    X1, X2 = np.meshgrid(x1, x2)
    Y = b1 * X1 + b2 * X2 + b0
    ax.plot_wireframe(X1, X2, Y)
    # 元データ表示
    ax.scatter3D(data[1], data[2], data[0], c='red')
    plt.show()

結果

> python MultipleRegressionAnalysis_2.py
Y = -17.118276566578807 x1 + 1.0700625679745137 x2 + 65.58796752824318