BP神经网络

# -*- coding: utf-8 -*-
"""
Created on Thu Mar  8 16:23:22 2018

@author: maeiei
"""

import numpy as np

def sigmoid (x , deriv = False):
    if(deriv == True):
        return x * (1 - x)
    return 1 / (1 + np.exp(-x))

x = np.array([[1, 1, 1,
               1, 0, 1,
               1, 0, 1,
               1, 0, 1,
               1, 1, 1], # 0
              [1, 1, 1,
               0, 1, 0,
               0, 1, 0,
               0, 1, 0,
               1, 1, 1], # 1
              [1, 1, 1,
               0, 0, 1,
               1, 1, 1,
               1, 0, 0,
               1, 1, 1], # 2
              [1, 1, 1,
               0, 0, 1,
               1, 1, 1,
               0, 0, 1,
               1, 1, 1], # 3
              [1, 0, 1,
               1, 0, 1,
               1, 1, 1,
               0, 0, 1,
               0, 0, 1], # 4
              [1, 1, 1,
               1, 0, 0,
               1, 1, 1,
               0, 0, 1,
               1, 1, 1], # 5
              [1, 1, 1,
               1, 0, 0,
               1, 1, 1,
               1, 0, 1,
               1, 1, 1], # 6
              [1, 1, 1,
               0, 0, 1,
               0, 0, 1,
               0, 0, 1,
               0, 0, 1], # 7
              [1, 1, 1,
               1, 0, 1,
               1, 1, 1,
               1, 0, 1,
               1, 1, 1], # 8
              [1, 1, 1,
               1, 0, 1,
               1, 1, 1,
               0, 0, 1,
               1, 1, 1] # 9
             ])
x = x.T
y = np.array([[0, 0, 0, 0],[0, 0, 0, 1],[0, 0, 1, 0],[0, 0, 1, 1],[0, 1, 0, 0],
              [0, 1, 0, 1],[0, 1, 1, 0],[0, 1, 1, 1],[1, 0, 0, 0],[1, 0, 0, 1]])
y = y.T
np.random.seed(1)
w0 = 2*np.random.random((4, 15)) -1
w1 = 2*np.random.random((4, 4))-1
print(w0)
print(w1)
for j in range(100000):
    l0 = x
    l1 = sigmoid(np.dot(w0, l0))
    l2 = sigmoid(np.dot(w1, l1))
    l2_error = y - l2
    if(j % 10000) == 0:
        print('Error' + str(np.mean(np.abs(l2_error))))
    l2_delta = l2_error * sigmoid(l2, deriv = True)
    l1_error = w1.dot(l2_delta)
    l1_delta = l1_error * sigmoid(l1, deriv = True)
   
    w1 += l2_delta.dot(l1.T)
    w0 += l1_delta.dot(l0.T)
   
for i in range(10):
    l0 = x[i]
    l1 = sigmoid(np.dot(l0, w0))
    l2 = sigmoid(np.dot(l1, w1))
    print(l2)   
   
d = np.array([1, 1, 1,
              1, 0, 1,
              1, 0, 1,
              1, 0, 1,
              1, 1, 1])
l0 = d
l1 = sigmoid(np.dot(w0, l0))
l2 = sigmoid(np.dot(w1, l1))  
print(l2) 

d = np.array( [1, 1, 1,
               0, 0, 1,
               1, 1, 1,
               1, 0, 0,
               1, 1, 1])
l0 = d
l1 = sigmoid(np.dot(w0, l0))
l2 = sigmoid(np.dot(w1, l1))  
print(l2) 


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转载自maeiei.iteye.com/blog/2412572