BP神经网络代码设计

 import pandas as pd

    
 import numpy as np
    
 import matplotlib.pyplot as plt
    
  
    
 def sigmoid(x):
    
     return 1/(1+np.exp(-x))
    
  
    
 def BP(data_tr, data_te, maxiter=1000):
    
     data_tr, data_te = np.array(data_tr), np.array(data_te)
    
     
    
     net_in = np.array([0.0, 0, -1])
    
     out_in = np.array([0.0, 0, 0, 0, -1])   # 输出层的输入，即隐层的输出
    
     
    
     w_mid = np.random.rand(3, 4) # 隐层神经元的权值&阈值
    
     w_out = np.random.rand(5)    # 输出层神经元的权值&阈值
    
  
    
     delta_w_out = np.zer