pytorch 基础学习–自用笔记(三)-回归模型
# encoding: utf-8
import time
import torch
import torch.nn.functional as F
from torch import nn
from torch.utils.data import DataLoader
from torchvision import datasets, transforms
# 定义超参数
batch_size = 64
learning_rate = 1e-3
num_epochs = 100
# 下载训练集 MNIST 手写数字训练集
train_dataset = datasets.FashionMNIST(
root='../datasets', train=True, transform=transforms.ToTensor(), download=True)
test_dataset = datasets.FashionMNIST(
root='../datasets', train=False, transform=transforms.ToTensor())
train_loader = DataLoader(train_dataset, batch_size=batch_size, shuffle=True)
test_loader = DataLoader(test_dataset, batch_size=batch_size, shuffle=False)
# 定义 Logistic Regression 模型
class Logistic_Regression(nn.Module):
def __init__(self, in_dim, n_class):
super(Logistic_Regression, self).__init__()
self.logistic = nn.Linear(in_dim, n_class)
def forward(self, x):
out = self.logistic(x)
return out
model = Logistic_Regression(28 * 28, 10) # 图片大小是28x28
use_gpu = torch.cuda.is_available() # 判断是否有GPU加速
if use_gpu:
model = model.cuda()
# 定义loss和optimizer
criterion = nn.CrossEntropyLoss()
optimizer = torch.optim.SGD(model.parameters(), lr=learning_rate)
# 开始训练
for epoch in range(num_epochs):
print('*' * 10)
print(f'epoch {epoch+1}')
since = time.time()
running_loss = 0.0
running_acc = 0.0
model.train()
for i, data in enumerate(train_loader, 1):
img, label = data
img = img.view(img.size(0), -1) # 将图片展开成 28x28,(64,784)
if use_gpu:
img = img.cuda()
label = label.cuda()
# 向前传播
out = model(img)
loss = criterion(out, label)
running_loss += loss.item()
_, pred = torch.max(out, 1)
running_acc += (pred==label).float().mean()
# 向后传播
optimizer.zero_grad()
loss.backward()
optimizer.step()
if i % 300 == 0:
print(f'[{epoch+1}/{num_epochs}] Loss: {running_loss/i:.6f}, Acc: {running_acc/i:.6f}')
print(f'Finish {epoch+1} epoch, Loss: {running_loss/i:.6f}, Acc: {running_acc/i:.6f}')
model.eval()
eval_loss = 0.
eval_acc = 0.
for data in test_loader:
img, label = data
img = img.view(img.size(0), -1)
if use_gpu:
img = img.cuda()
label = label.cuda()
with torch.no_grad():
out = model(img)
loss = criterion(out, label)
eval_loss += loss.item()
_, pred = torch.max(out, 1)
eval_acc += (pred == label).float().mean()
print(f'Test Loss: {eval_loss/len(test_loader):.6f}, Acc: {eval_acc/len(test_loader):.6f}')
print(f'Time:{(time.time()-since):.1f} s')
# 保存模型
torch.save(model.state_dict(), './logstic.pth')
本图文内容来源于网友网络收集整理提供,作为学习参考使用,版权属于原作者。
THE END
二维码