写一段搭建硬间隔SVM分类器的算法,避免出现Terminated (singular KKT matrix),同时采用x_trainPca[936],y_label[936]做训练集
时间: 2024-01-10 17:03:25 浏览: 153
好的,以下是一段基于硬间隔支持向量机的分类器的算法:
```python
import numpy as np
# 定义一个函数,用于计算SVM的损失函数
def svm_loss(weights, bias, x, y, reg_strength):
# 计算预测值
scores = np.dot(x, weights) + bias
# 计算损失函数
loss = np.maximum(0, 1 - y * scores)
# 加上正则化项
loss += 0.5 * reg_strength * np.dot(weights, weights)
# 计算平均损失
avg_loss = np.mean(loss)
return avg_loss
# 定义一个函数,用于优化SVM的参数
def svm_train(x, y, reg_strength, learning_rate, num_iters):
# 初始化权重和偏置
weights = np.zeros(x.shape[1])
bias = 0
# 定义一个变量,用于记录损失函数的变化
loss_history = []
# 使用随机梯度下降法优化参数
for i in range(num_iters):
# 随机选择一个样本
idx = np.random.randint(x.shape[0])
xi = x[idx]
yi = y[idx]
# 计算预测值
score = np.dot(xi, weights) + bias
# 如果预测值和标签相反,则更新参数
if yi * score < 1:
dweights = reg_strength * weights - yi * xi
dbias = -yi
else:
dweights = reg_strength * weights
dbias = 0
# 更新参数
weights -= learning_rate * dweights
bias -= learning_rate * dbias
# 计算损失函数
loss = svm_loss(weights, bias, x, y, reg_strength)
loss_history.append(loss)
return weights, bias, loss_history
# 加载数据集
x_train = np.load('x_trainPca.npy')
y_train = np.load('y_label.npy')
# 将标签转换为1和-1
y_train = np.where(y_train == 0, -1, 1)
# 定义正则化强度和学习率
reg_strength = 1e-5
learning_rate = 1e-2
# 训练SVM模型
weights, bias, loss_history = svm_train(x_train[:936], y_train[:936], reg_strength, learning_rate, num_iters=10000)
# 输出模型参数
print("weights:", weights)
print("bias:", bias)
# 计算训练集上的准确率
scores = np.dot(x_train, weights) + bias
y_pred = np.where(scores > 0, 1, -1)
accuracy = np.mean(y_pred == y_train)
print("training accuracy:", accuracy)
```
在这个算法中,我们首先定义了一个函数`svm_loss`,用于计算SVM的损失函数。然后定义了一个函数`svm_train`,用于优化SVM的参数。这个函数使用随机梯度下降法来优化参数,每次随机选择一个样本进行更新。最后,我们加载了数据集,并使用`svm_train`函数训练SVM模型。训练完成后,我们计算了模型的训练集准确率,并输出了模型的参数。注意,我们只使用了前936个样本进行训练,可以根据需要调整这个数量。
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