X = np.array([ [0,0,1],[0,1,1],[1,0,1],[1,1,1] ]) y = np.array([[0,1,1,0]]).T syn0 = 2*np.random.random((3,4)) - 1 syn1 = 2*np.random.random((4,1)) - 1 for j in xrange(60000): l1 = 1/(1+np.exp(-(np.dot(X,syn0)))) l2 = 1/(1+np.exp(-(np.dot(l1,syn1)))) l2_delta = (y - l2)*(l2*(1-l2)) l1_delta = l2_delta.dot(syn1.T) * (l1 * (1-l1)) syn1 += l1.T.dot(l2_delta) syn0 += X.T.dot(l1_delta) import numpy as np # sigmoid function def nonlin(x,deriv=False): if(deriv==True): return x*(1-x) return 1/(1+np.exp(-x)) # input dataset X = np.array([ [0,0,1], [0,1,1], [1,0,1], [1,1,1] ]) # output dataset y = np.array([[0,0,1,1]]).T # seed random numbers to make calculation # deterministic (just a good practice) np.random.seed(1) # initialize weights randomly with mean 0 syn0 = 2*np.random.random((3,1)) - 1 for iter in xrange(10000): # forward propagation l0 = X l1 = nonlin(np.dot(l0,syn0)) # how much did we miss? l1_error = y - l1 # multiply how much we missed by the # slope of the sigmoid at the values in l1 l1_delta = l1_error * nonlin(l1,True) # update weights syn0 += np.dot(l0.T,l1_delta) print "Output After Training:" print l1
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