python - 为什么没有打印任何行并且估计系数为 NaN？

Question

代码使用numpy.genfromtxt将数据集导入到代码中，然后尝试通过散点图绘制回归线。但是，散点图会打印，而线条不会打印。估计系数也输出 NaN。问题出在哪里？

import numpy as np 
import matplotlib.pyplot as plt 
from numpy import genfromtxt

def estimate_coef(x, y): 
    # number of observations/points 
    n = np.size(x) 

    # mean of x and y vector 
    m_x, m_y = np.mean(x), np.mean(y) 

    # calculating cross-deviation and deviation about x 
    SS_xy = np.sum(y*x) - n*m_y*m_x 
    SS_xx = np.sum(x*x) - n*m_x*m_x 

    # calculating regression coefficients 
    b_1 = SS_xy / SS_xx 
    b_0 = m_y - b_1*m_x 

    return(b_0, b_1) 

def plot_regression_line(x, y, b): 
    # plotting the actual points as scatter plot 
    plt.scatter(x, y, color = "m", 
               marker = "o", s = 30) 

    # predicted response vector 
    y_pred = b[0] + b[1]*x 

    # plotting the regression line 
    plt.plot(x, y_pred, color = "g") 

    # putting labels 
    plt.xlabel('x') 
    plt.ylabel('y') 

    # function to show plot 
    plt.show() 

def main(): 
    # observations 
    x = genfromtxt('/Users/divyanshuvarma/Downloads/graduate-admissions/Admission_Predict.csv', delimiter=',',usecols=(1))
    y = genfromtxt('/Users/divyanshuvarma/Downloads/graduate-admissions/Admission_Predict.csv', delimiter=',',usecols=(8))


    # estimating coefficients 
    b = estimate_coef(x, y) 
    print("Estimated coefficients:\nb_0 = {}  \
          \nb_1 = {}".format(b[0], b[1])) 

    # plotting regression line 
    plot_regression_line(x, y, b) 

if __name__ == "__main__": 
    main() 

Answer 1

函数estimate_coef中有一个除法b_1 = SS_xy/SS_xx。您是否打印出值SS_xx，也许它为零？希望有帮助。