请你在不调用python支持向量机的库的情况下帮我用python编写一个支持向量机分类的程序
时间: 2024-05-09 21:18:50 浏览: 104
好的,下面是一个简单的支持向量机分类程序,使用的是Python和NumPy库:
```python
import numpy as np
class SVM:
def __init__(self, C=1.0, kernel='linear', degree=3, gamma='auto', coef0=0.0):
self.C = C
self.kernel = kernel
self.degree = degree
self.gamma = gamma
self.coef0 = coef0
self.alpha = None
self.b = None
def fit(self, X, y):
n_samples, n_features = X.shape
if self.gamma == 'auto':
self.gamma = 1 / n_features
if self.kernel == 'linear':
K = np.dot(X, X.T)
elif self.kernel == 'poly':
K = (self.gamma * np.dot(X, X.T) + self.coef0) ** self.degree
elif self.kernel == 'rbf':
K = np.zeros((n_samples, n_samples))
for i in range(n_samples):
for j in range(n_samples):
K[i,j] = np.exp(-self.gamma * np.linalg.norm(X[i]-X[j])**2)
else:
raise ValueError('Unsupported kernel function')
P = np.outer(y, y) * K
q = -np.ones(n_samples)
G = np.vstack((-np.eye(n_samples), np.eye(n_samples)))
h = np.hstack((np.zeros(n_samples), np.ones(n_samples) * self.C))
A = y.reshape(1, -1)
b = np.zeros(1)
from cvxopt import solvers
solvers.options['show_progress'] = False
sol = solvers.qp(matrix(P), matrix(q), matrix(G), matrix(h), matrix(A), matrix(b))
alpha = np.array(sol['x']).flatten()
support_vectors = alpha > 1e-5
self.alpha = alpha[support_vectors]
self.b = y[support_vectors] - np.dot(K[support_vectors][:,support_vectors], self.alpha * y[support_vectors])
self.b = np.mean(self.b)
self.support_vectors = X[support_vectors]
self.support_vectors_y = y[support_vectors]
def predict(self, X):
if self.kernel == 'linear':
scores = np.dot(X, self.support_vectors.T)
elif self.kernel == 'poly':
scores = (self.gamma * np.dot(X, self.support_vectors.T) + self.coef0) ** self.degree
elif self.kernel == 'rbf':
scores = np.zeros((X.shape[0], self.support_vectors.shape[0]))
for i in range(X.shape[0]):
for j in range(self.support_vectors.shape[0]):
scores[i,j] = np.exp(-self.gamma * np.linalg.norm(X[i]-self.support_vectors[j])**2)
else:
raise ValueError('Unsupported kernel function')
return np.sign(np.dot(scores, self.alpha * self.support_vectors_y) + self.b)
```
这个程序实现了一个简单的支持向量机分类器,包含了线性、多项式和高斯核函数三种不同的核函数。使用的是凸优化库cvxopt来求解支持向量机的优化问题。可以通过调用SVM类的fit方法来训练模型,然后通过调用predict方法来进行预测。
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