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[英]How to create simple 3-layer neural network and teach it using supervised learning?
[英]3 layer neural network using only numpy in python
我正在僅使用python中的numpy創建一個簡單的神經網絡。我正在關注本教程https://iamtrask.github.io/2015/07/12/basic-python-network/,並且更改了3層的代碼上面提到的鏈接中的神經網絡如下。我需要隨時調用單獨的方法。 但這給了我以下錯誤。 我想知道的是為什么我會收到此錯誤? 因為我是python的初學者,所以我不知道為什么會收到此錯誤? 因此,請有人幫助我解決這個問題。
import numpy as np
class NeuralNetwork():
def __init__(self):
self.X = np.array([[0, 0, 1],
[0, 1, 1],
[1, 0, 1],
[1, 1, 1]])
self.y = np.array([[0],
[1],
[1],
[0]])
np.random.seed(1)
# randomly initialize our weights with mean 0
self.syn0 = 2 * np.random.random((3, 4)) - 1
self.syn1 = 2 * np.random.random((4, 1)) - 1
def nonlin(x, deriv=False):
if (deriv == True):
return x * (1 - x)
return 1 / (1 + np.exp(-x))
def train(self,steps):
for j in xrange(steps):
# Feed forward through layers 0, 1, and 2
l0 = self.X
print("came 1")
l1 = self.nonlin(np.dot(l0, self.syn0))
print("came 2")
l2 = self.nonlin(np.dot(l1, self.syn1))
# how much did we miss the target value?
l2_error = self.y - l2
if (j % 10000) == 0:
print "Error:" + str(np.mean(np.abs(l2_error)))
# in what direction is the target value?
# were we really sure? if so, don't change too much.
l2_delta = l2_error * self.nonlin(l2, deriv=True)
# how much did each l1 value contribute to the l2 error (according to the weights)?
l1_error = l2_delta.dot(self.syn1.T)
# in what direction is the target l1?
# were we really sure? if so, don't change too much.
l1_delta = l1_error * self.nonlin(l1, deriv=True)
self.syn1 += l1.T.dot(l2_delta)
self.syn0 += l0.T.dot(l1_delta)
print("Output after training:")
print(l2)
if __name__ == '__main__':
ann=NeuralNetwork()
ann.train(6000)
我收到的錯誤如下所示
Traceback (most recent call last):
File "C:/Users/Ssa/Desktop/Neural-Network-using-numpy-master/Neural-Network-using-numpy-master/outbreak_test/outbreak_test4.py", line 63, in <module>
ann.train(6000)
File "C:/Users/Ssa/Desktop/Neural-Network-using-numpy-master/Neural-Network-using-numpy-master/outbreak_test/outbreak_test4.py", line 34, in train
l1 = self.nonlin(np.dot(l0, self.syn0))
File "C:/Users/Ssa/Desktop/Neural-Network-using-numpy-master/Neural-Network-using-numpy-master/outbreak_test/outbreak_test4.py", line 23, in nonlin
if (deriv == True):
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
Process finished with exit code 1
問題是,您已將函數nonlin
定義為非類成員函數。 這意味着該函數的第一個參數不是self
(對對象的引用)。 您可以使代碼以兩種不同的方式工作:
1)將nonlin
函數更改為此:
def nonlin(self, x, deriv=True):
...
2)使nonlin
函數成為靜態方法:
@staticmethod
def nonlin(x, deriv=True):
...
您可以在此處找到有關第二種方法的更多信息。 兩種方法都是有效的,但我認為第一種方法似乎更適合面向對象的編程。
nonlin
需要接受一個self
參數,否則, self
將被視為x
,而x
視為deriv
。
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