import random
import numpy as np
t = np.array([400, 336, 369, 232, 540])
X = np.array([[2104, 3], [1600, 3], [2400, 3], [1416, 2], [3000, 4]])
theta = [1, 1]
alpha = 0.0000001
epsilon = 1e-5
loss = 10
error = 0
max_iters = 10000
iter_count = 0
while (loss > epsilon and iter_count < max_iters):
loss = 0
i = random.randint(0, 4)
j = (i + 1) % 4
y0 = theta[0] * X[i][0] + theta[1] * X[i][1]
y1 = theta[0] * X[j][0] + theta[1] * X[j][1]
theta[0] = theta[0] - alpha * (1 / 2) * (
(y0 - t[i]) * X[i][0] + (y1 - t[j]) * X[j][0])
theta[1] = theta[1] - alpha * (1 / 2) * (
(y0 - t[i]) * X[i][1] + (y1 - t[j]) * X[j][1])
for i in range(3):
y = theta[0] * X[i][0] + theta[1] * X[i][1]
error = (1 /2) * (y - t[i]) ** 2
loss = loss + error
iter_count += 1
print('theta: ', theta)
print('final loss: ', loss)
print('iters: ', iter_count)
运行结果
"D:py projectexervenvscriptspython.exe" "D:/py project/exer/SGD.py" theta: [0.17134841309495594, 1.0143142804721434] final loss: 3417.732911609579 iters: 10000 Process finished with exit code 0
