你可以编写一段简单的神经网络代码吗
时间: 2023-03-26 22:01:56 浏览: 52
当然可以,以下是一个简单的神经网络代码示例:
```python
import numpy as np
# 定义输入数据
X = np.array([[, , 1], [, 1, 1], [1, , 1], [1, 1, 1]])
# 定义输出数据
y = np.array([[], [1], [1], []])
# 定义激活函数
def sigmoid(x):
return 1 / (1 + np.exp(-x))
# 定义神经网络模型
class NeuralNetwork:
def __init__(self):
self.weights1 = np.random.randn(3, 4)
self.weights2 = np.random.randn(4, 1)
def forward(self, X):
self.layer1 = sigmoid(np.dot(X, self.weights1))
self.layer2 = sigmoid(np.dot(self.layer1, self.weights2))
return self.layer2
def backward(self, X, y, output):
self.output_error = y - output
self.output_delta = self.output_error * sigmoid(output, derivative=True)
self.layer1_error = self.output_delta.dot(self.weights2.T)
self.layer1_delta = self.layer1_error * sigmoid(self.layer1, derivative=True)
self.weights1 += X.T.dot(self.layer1_delta)
self.weights2 += self.layer1.T.dot(self.output_delta)
def train(self, X, y):
output = self.forward(X)
self.backward(X, y, output)
# 训练神经网络
nn = NeuralNetwork()
for i in range(10000):
nn.train(X, y)
# 预测结果
print(nn.forward(np.array([1, , ])))
```
这段代码实现了一个简单的神经网络,用于解决异或逻辑运算问题。