作业：
day43的时候我们安排大家对自己找的数据集用简单cnn训练，现在可以尝试下借助这几天的知识来实现精度的进一步提高
python
import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import DataLoader
from torchvision import datasets, transforms, models
import torch.nn.functional as F
from PIL import Image
import os
import numpy as np
import matplotlib.pyplot as plt
from tqdm import tqdm
import cv2
import random
# 设置随机种子确保结果可复现
torch.manual_seed(42)
np.random.seed(42)
random.seed(42)
# 设置中文字体支持
plt.rcParams["font.family"] = ["SimHei"]
plt.rcParams['axes.unicode_minus'] = False # 解决负号显示问题
# 数据集路径
data_dir = r"D:\archive (1)\MY_data"
# 数据预处理和增强
train_transform = transforms.Compose([
transforms.RandomResizedCrop(224),
transforms.RandomHorizontalFlip(),
transforms.RandomRotation(10),
transforms.ColorJitter(brightness=0.1, contrast=0.1, saturation=0.1),
transforms.ToTensor(),
transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])
])
test_transform = transforms.Compose([
transforms.Resize(256),
transforms.CenterCrop(224),
transforms.ToTensor(),
transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])
])
# 加载数据集
train_dataset = datasets.ImageFolder(os.path.join(data_dir, 'train'), transform=train_transform)
test_dataset = datasets.ImageFolder(os.path.join(data_dir, 'test'), transform=test_transform)
# 创建数据加载器
batch_size = 32
train_loader = DataLoader(train_dataset, batch_size=batch_size, shuffle=True, num_workers=4)
test_loader = DataLoader(test_dataset, batch_size=batch_size, shuffle=False, num_workers=4)
# 获取类别名称
classes = train_dataset.classes
print(f"类别: {classes}")
# CBAM注意力机制实现
class ChannelAttention(nn.Module):
def __init__(self, in_channels, reduction_ratio=16):
super(ChannelAttention, self).__init__()
self.avg_pool = nn.AdaptiveAvgPool2d(1)
self.max_pool = nn.AdaptiveMaxPool2d(1)
self.fc = nn.Sequential(
nn.Conv2d(in_channels, in_channels // reduction_ratio, 1, bias=False),
nn.ReLU(),
nn.Conv2d(in_channels // reduction_ratio, in_channels, 1, bias=False)
)
self.sigmoid = nn.Sigmoid()
def forward(self, x):
avg_out = self.fc(self.avg_pool(x))
max_out = self.fc(self.max_pool(x))
out = avg_out + max_out
return self.sigmoid(out)
class SpatialAttention(nn.Module):
def __init__(self, kernel_size=7):
super(SpatialAttention, self).__init__()
self.conv = nn.Conv2d(2, 1, kernel_size, padding=kernel_size//2, bias=False)
self.sigmoid = nn.Sigmoid()
def forward(self, x):
avg_out = torch.mean(x, dim=1, keepdim=True)
max_out, _ = torch.max(x, dim=1, keepdim=True)
x_cat = torch.cat([avg_out, max_out], dim=1)
out = self.conv(x_cat)
return self.sigmoid(out)
class CBAM(nn.Module):
def __init__(self, in_channels, reduction_ratio=16, kernel_size=7):
super(CBAM, self).__init__()
self.channel_attention = ChannelAttention(in_channels, reduction_ratio)
self.spatial_attention = SpatialAttention(kernel_size)
def forward(self, x):
x = x * self.channel_attention(x)
x = x * self.spatial_attention(x)
return x
# 定义改进的CNN模型（支持多种预训练模型和CBAM注意力机制）
class EnhancedFruitClassifier(nn.Module):
def __init__(self, num_classes=10, model_name='resnet18', use_cbam=True):
super(EnhancedFruitClassifier, self).__init__()
self.use_cbam = use_cbam
# 根据选择加载不同的预训练模型
if model_name == 'resnet18':
self.model = models.resnet18(pretrained=True)
in_features = self.model.fc.in_features
# 保存原始层以便后续使用
self.features = nn.Sequential(*list(self.model.children())[:-2])
self.avgpool = self.model.avgpool
elif model_name == 'resnet50':
self.model = models.resnet50(pretrained=True)
in_features = self.model.fc.in_features
self.features = nn.Sequential(*list(self.model.children())[:-2])
self.avgpool = self.model.avgpool
elif model_name == 'efficientnet_b0':
self.model = models.efficientnet_b0(pretrained=True)
in_features = self.model.classifier[1].in_features
self.features = nn.Sequential(*list(self.model.children())[:-1])
self.avgpool = nn.AdaptiveAvgPool2d(1)
else:
raise ValueError(f"不支持的模型: {model_name}")
# 冻结大部分预训练层
for param in list(self.model.parameters())[:-5]:
param.requires_grad = False
# 添加CBAM注意力机制
if use_cbam:
self.cbam = CBAM(in_features)
# 修改最后一层以适应我们的分类任务
self.fc = nn.Linear(in_features, num_classes)
def forward(self, x):
# 特征提取
x = self.features(x)
# 应用CBAM注意力机制
if self.use_cbam:
x = self.cbam(x)
# 全局池化
x = self.avgpool(x)
x = torch.flatten(x, 1)
# 分类
x = self.fc(x)
return x
# 初始化模型 - 可以选择不同的预训练模型和是否使用CBAM
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
model = EnhancedFruitClassifier(
num_classes=len(classes),
model_name='resnet18', # 可选: 'resnet18', 'resnet50', 'efficientnet_b0'
use_cbam=True
).to(device)
# 定义损失函数和优化器
criterion = nn.CrossEntropyLoss()
optimizer = optim.Adam(filter(lambda p: p.requires_grad, model.parameters()), lr=0.001)
scheduler = optim.lr_scheduler.StepLR(optimizer, step_size=5, gamma=0.1)
# 训练模型
def train_model(model, train_loader, criterion, optimizer, scheduler, device, epochs=10):
model.train()
for epoch in range(epochs):
running_loss = 0.0
correct = 0
total = 0
progress_bar = tqdm(enumerate(train_loader), total=len(train_loader))
for i, (inputs, labels) in progress_bar:
inputs, labels = inputs.to(device), labels.to(device)
optimizer.zero_grad()
outputs = model(inputs)
loss = criterion(outputs, labels)
loss.backward()
optimizer.step()
running_loss += loss.item()
_, predicted = outputs.max(1)
total += labels.size(0)
correct += predicted.eq(labels).sum().item()
progress_bar.set_description(f"Epoch {epoch+1}/{epochs}, "
f"Loss: {running_loss/(i+1):.4f}, "
f"Acc: {100.*correct/total:.2f}%")
scheduler.step()
print(f"Epoch {epoch+1}/{epochs}, "
f"Train Loss: {running_loss/len(train_loader):.4f}, "
f"Train Acc: {100.*correct/total:.2f}%")
return model
# 评估模型
def evaluate_model(model, test_loader, device):
model.eval()
correct = 0
total = 0
class_correct = list(0. for i in range(len(classes)))
class_total = list(0. for i in range(len(classes)))
with torch.no_grad():
for inputs, labels in test_loader:
inputs, labels = inputs.to(device), labels.to(device)
outputs = model(inputs)
_, predicted = outputs.max(1)
total += labels.size(0)
correct += predicted.eq(labels).sum().item()
# 计算每个类别的准确率
for i in range(len(labels)):
label = labels[i]
class_correct[label] += (predicted[i] == label).item()
class_total[label] += 1
print(f"测试集整体准确率: {100.*correct/total:.2f}%")
# 打印每个类别的准确率
for i in range(len(classes)):
if class_total[i] > 0:
print(f"{classes[i]} 类别的准确率: {100.*class_correct[i]/class_total[i]:.2f}%")
else:
print(f"{classes[i]} 类别的样本数为0")
return 100.*correct/total
# Grad-CAM实现
class GradCAM:
def __init__(self, model, target_layer):
self.model = model
self.target_layer = target_layer
self.gradients = None
self.activations = None
# 注册钩子
self.hook_handles = []
# 保存梯度的钩子
def backward_hook(module, grad_in, grad_out):
self.gradients = grad_out[0]
return None
# 保存激活值的钩子
def forward_hook(module, input, output):
self.activations = output
return None
self.hook_handles.append(
target_layer.register_forward_hook(forward_hook)
)
self.hook_handles.append(
target_layer.register_backward_hook(backward_hook)
)
def __call__(self, x, class_idx=None):
# 前向传播
model_output = self.model(x)
if class_idx is None:
class_idx = torch.argmax(model_output, dim=1)
# 构建one-hot向量
one_hot = torch.zeros_like(model_output)
one_hot[0, class_idx] = 1
# 反向传播
self.model.zero_grad()
model_output.backward(gradient=one_hot, retain_graph=True)
# 计算权重（全局平均池化梯度）
weights = torch.mean(self.gradients, dim=(2, 3), keepdim=True)
# 加权组合激活映射
cam = torch.sum(weights * self.activations, dim=1).squeeze()
# ReLU激活，因为我们只关心对类别有正贡献的区域
cam = F.relu(cam)
# 归一化
if torch.max(cam) > 0:
cam = cam / torch.max(cam)
# 调整大小到输入图像尺寸
cam = F.interpolate(cam.unsqueeze(0).unsqueeze(0),
size=(x.size(2), x.size(3)),
mode='bilinear',
align_corners=False).squeeze()
return cam.detach().cpu().numpy(), class_idx.item()
def remove_hooks(self):
for handle in self.hook_handles:
handle.remove()
# 可视化Grad-CAM结果
def visualize_gradcam(img_path, model, target_layer, classes, device):
# 加载并预处理图像
img = Image.open(img_path).convert('RGB')
img_tensor = test_transform(img).unsqueeze(0).to(device)
# 初始化Grad-CAM
grad_cam = GradCAM(model, target_layer)
# 获取Grad-CAM热力图
cam, pred_class = grad_cam(img_tensor)
# 反归一化图像以便显示
img_np = img_tensor.squeeze().cpu().numpy().transpose((1, 2, 0))
img_np = img_np * np.array([0.229, 0.224, 0.225]) + np.array([0.485, 0.456, 0.406])
img_np = np.clip(img_np, 0, 1)
# 调整热力图大小
heatmap = cv2.resize(cam, (img_np.shape[1], img_np.shape[0]))
# 创建彩色热力图
heatmap = np.uint8(255 * heatmap)
heatmap = cv2.applyColorMap(heatmap, cv2.COLORMAP_JET)
heatmap = cv2.cvtColor(heatmap, cv2.COLOR_BGR2RGB)
heatmap = np.float32(heatmap) / 255
# 叠加原始图像和热力图
superimposed_img = heatmap * 0.4 + img_np
superimposed_img = np.clip(superimposed_img, 0, 1)
# 显示结果
plt.figure(figsize=(15, 5))
plt.subplot(131)
plt.imshow(img_np)
plt.title('原始图像')
plt.axis('off')
plt.subplot(132)
plt.imshow(cam, cmap='jet')
plt.title('Grad-CAM热力图')
plt.axis('off')
plt.subplot(133)
plt.imshow(superimposed_img)
plt.title(f'叠加图像\n预测类别: {classes[pred_class]}')
plt.axis('off')
plt.tight_layout()
plt.show()
# 预测函数
def predict_image(img_path, model, classes, device):
# 加载并预处理图像
img = Image.open(img_path).convert('RGB')
img_tensor = test_transform(img).unsqueeze(0).to(device)
# 预测
model.eval()
with torch.no_grad():
outputs = model(img_tensor)
probs = F.softmax(outputs, dim=1)
top_probs, top_classes = probs.topk(5, dim=1)
# 打印预测结果
print(f"图像: {os.path.basename(img_path)}")
print("预测结果:")
for i in range(top_probs.size(1)):
print(f"{classes[top_classes[0, i]]}: {top_probs[0, i].item() * 100:.2f}%")
return top_classes[0, 0].item()
# 主函数
def main():
# 训练模型
print("开始训练模型...")
trained_model = train_model(model, train_loader, criterion, optimizer, scheduler, device, epochs=5)
# 评估模型
print("\n评估模型...")
evaluate_model(trained_model, test_loader, device)
# 保存模型
model_path = "fruit_classifier.pth"
torch.save(trained_model.state_dict(), model_path)
print(f"\n模型已保存至: {model_path}")
# 可视化Grad-CAM结果
print("\n可视化Grad-CAM结果...")
# 从测试集中随机选择几张图像进行可视化
predict_dir = os.path.join(data_dir, 'predict')
if os.path.exists(predict_dir):
# 使用predict目录中的图像
image_files = [os.path.join(predict_dir, f) for f in os.listdir(predict_dir)
if f.lower().endswith(('.png', '.jpg', '.jpeg'))]
if len(image_files) > 0:
# 随机选择2张图像
sample_images = random.sample(image_files, min(2, len(image_files)))
for img_path in sample_images:
print(f"\n处理图像: {img_path}")
# 预测图像类别
pred_class = predict_image(img_path, trained_model, classes, device)
# 可视化Grad-CAM
if hasattr(trained_model, 'model') and hasattr(trained_model.model, 'layer4'):
# 对于ResNet系列模型
visualize_gradcam(img_path, trained_model, trained_model.model.layer4[-1].conv2, classes, device)
else:
# 对于其他模型，使用最后一个特征层
visualize_gradcam(img_path, trained_model, list(trained_model.features.children())[-1], classes, device)
else:
print(f"predict目录为空，无法进行可视化")
else:
print(f"predict目录不存在，无法进行可视化")
if __name__ == "__main__":
main()
python
类别: ['Apple', 'Banana', 'avocado', 'cherry', 'kiwi', 'mango', 'orange', 'pinenapple', 'strawberries', 'watermelon']
开始训练模型...
Epoch 1/5, Loss: 0.8748, Acc: 74.23%: 100%|██████████| 72/72 [00:08<00:00, 8.66it/s]
Epoch 1/5, Train Loss: 0.8748, Train Acc: 74.23%
Epoch 2/5, Loss: 0.4802, Acc: 83.83%: 100%|██████████| 72/72 [00:07<00:00, 10.02it/s]
Epoch 2/5, Train Loss: 0.4802, Train Acc: 83.83%
Epoch 3/5, Loss: 0.4239, Acc: 86.35%: 100%|██████████| 72/72 [00:07<00:00, 9.69it/s]
Epoch 3/5, Train Loss: 0.4239, Train Acc: 86.35%
Epoch 4/5, Loss: 0.4179, Acc: 85.96%: 100%|██████████| 72/72 [00:07<00:00, 9.64it/s]
Epoch 4/5, Train Loss: 0.4179, Train Acc: 85.96%
Epoch 5/5, Loss: 0.3747, Acc: 87.44%: 100%|██████████| 72/72 [00:07<00:00, 9.68it/s]
Epoch 5/5, Train Loss: 0.3747, Train Acc: 87.44%
评估模型...
测试集整体准确率: 66.83%
Apple 类别的准确率: 80.90%
Banana 类别的准确率: 0.00%
avocado 类别的准确率: 1.89%
cherry 类别的准确率: 93.33%
kiwi 类别的准确率: 93.33%
mango 类别的准确率: 48.57%
orange 类别的准确率: 97.94%
pinenapple 类别的准确率: 96.19%
strawberries 类别的准确率: 90.29%
watermelon 类别的准确率: 71.43%
模型已保存至: fruit_classifier.pth
可视化Grad-CAM结果...
处理图像: D:\archive (1)\MY_data\predict\img_341.jpeg
图像: img_341.jpeg
预测结果:
mango: 90.52%
orange: 3.99%
kiwi: 2.45%
avocado: 1.86%
Apple: 0.98%
python
处理图像: D:\archive (1)\MY_data\predict\1.jpeg
图像: 1.jpeg
预测结果:
Apple: 95.86%
cherry: 2.94%
Banana: 0.71%
avocado: 0.24%
strawberries: 0.19%