『PyTorch』第六弹_最小二乘法的不同实现手段(待续)

Posted 2020-10-24 叠加态的猫

PyTorch的Variable

import torch as t
from torch.autograd import Variable as V
import matplotlib.pyplot as plt
from IPython import display

# 指定随机数种子
t.manual_seed(1000)

def get_fake_data(batch_size=8):
    x = t.rand(batch_size,1)*20
    y = x * 2 + 3 + 3*t.randn(batch_size,1)
    return x, y

x, y = get_fake_data()
plt.scatter(x.squeeze(), y.squeeze())

w = V(t.rand(1,1),requires_grad=True)
b = V(t.rand(1,1),requires_grad=True)

lr = 0.001

for ii in range(8000):
    x, y = get_fake_data()
    x, y = V(x), V(y)
    # print(x, y)
    y_pred = x.mm(w) + b.expand_as(x)

    loss = 0.5*(y_pred - y)**2
    loss = loss.sum()  # 集结loss向量

    loss.backward()

    w.data.sub_(lr * w.grad.data)
    b.data.sub_(lr * b.grad.data)

    w.grad.data.zero_()
    b.grad.data.zero_()

    if ii % 1000 == 0:
        display.clear_output(wait=True)
        x = t.arange(0,20).view(-1,1)
        y = x.mm(w.data) + b.data.expand_as(x)
        plt.plot(x.numpy(), y.numpy())
        x2, y2 = get_fake_data(batch_size=20)
        plt.scatter(x2, y2)

        plt.xlim(0,20)
        plt.ylim(0,40)
        plt.show()
        
print(w.data.squeeze(), b.data.squeeze())