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python - python脚本问题-语法无效

问题描述

为了更好地理解机器学习和神经网络的工作原理，我从这里提取的以下代码不起作用。它在第 31 行不断产生“无效语法”错误：

self.weights1 += d_weights1

这是失败的功能： 

    def backprop(self):
        # application of the chain rule to find derivative of the loss function with respect to weights2 and weights1
        d_weights2 = np.dot(self.layer1.T, (2*(self.y - self.output) * sigmoid_derivative(self.output)))
        d_weights1 = np.dot(self.input.T, (np.dot(2*(self.y - self.output) * sigmoid_derivative(self.output), self.weights2.T) * sigmoid_derivative(self.layer1))

        # update the weights with the derivative (slope) of the loss function        
        self.weights1 += d_weights1
        self.weights2 += d_weights2

标签： python

解决方案

您忘记在第 4 行末尾加括号

d_weights1 = np.dot(self.input.T, (np.dot(2*(self.y - self.output) * sigmoid_derivative(self.output), self.weights2.T) * sigmoid_derivative(self.layer1))

这是更正：

d_weights1 = np.dot(self.input.T, (np.dot(2*(self.y - self.output) * sigmoid_derivative(self.output), self.weights2.T) * sigmoid_derivative(self.layer1)))

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