cats&dogs dataset Resnet50練習 by pytorch Part 2.

2022 iThome 鐵人賽

DAY 1

自我挑戰組

resnet, resnext練習系列第 2 篇

14th鐵人賽

Bruce27

2022-09-08 21:58:51

1745 瀏覽

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承接上次的code

Part 9.選擇處理器

### GPU
# device = torch.device('cuda') if torch.cuda.is_available() else torch.device('cpu')
device = torch.device('cpu')
print(device)

我自己的電腦GPU的記憶體不是很足夠，所以我是用自己的CPU跑的(跑了兩天左右)

Part 10.設定計算準確率的Function

### Function to calculate accuracy
def accuracy(preds, trues):
    
    ### Converting preds to 0 or 1
    preds = [1 if preds[i] >= 0.5 else 0 for i in range(len(preds))]
    
    ### Calculating accuracy by comparing predictions with true labels
    acc = [1 if preds[i] == trues[i] else 0 for i in range(len(preds))]
    
    ### Summing over all correct predictions
    acc = np.sum(acc) / len(preds)
    
    return (acc * 100)

這個 Function會給預測函數設定一個閥值(0.5)將其作2元分類，然後再將其與測試組做對比算出 accurancy

Part 11.設定每個 Epoch的 gradient update(PyTorch)

1.Reseting Gradients,當GPU不夠大時呼叫'optimizer.zero_grad()'#reset防止每一次迭代後，累加gradient狀態一直處於GPU中未被釋放。
2.Forward,'preds = model(images)'是將data傳入model進行forward propagation
3.Calculating Loss,'_loss = criterion(preds, labels)',計算loss
4.Backward,'_loss.backward()'根據loss進行back propagation，計算gradient
5.Update,'optimizer.step()' 更新gradient descent
source: https://meetonfriday.com/posts/18392404/
每訓練一回所做的事:

### Function - One Epoch Train
def train_one_epoch(train_data_loader):
    
    ### Local Parameters
    epoch_loss = []
    epoch_acc = []
    start_time = time.time()
    
    ###Iterating over data loader
    for images, labels in train_data_loader:
        
        #Loading images and labels to device
        images = images.to(device)
        labels = labels.to(device)
        labels = labels.reshape((labels.shape[0], 1)) # [N, 1] - to match with preds shape
        
        #Reseting Gradients (reset)
        optimizer.zero_grad()
        
        #Forward
        preds = model(images)
        
        #Calculating Loss
        _loss = criterion(preds, labels)
        loss = _loss.item()
        epoch_loss.append(loss)
        
        #Calculating Accuracy
        acc = accuracy(preds, labels)
        epoch_acc.append(acc)
        
        #Backward (update)
        _loss.backward()
        optimizer.step()
    
    ###Overall Epoch Results
    end_time = time.time()
    total_time = end_time - start_time
    
    ###Acc and Loss
    epoch_loss = np.mean(epoch_loss)
    epoch_acc = np.mean(epoch_acc)
    
    ###Storing results to logs
    train_logs["loss"].append(epoch_loss)
    train_logs["accuracy"].append(epoch_acc)
    train_logs["time"].append(total_time)
        
    return epoch_loss, epoch_acc, total_time

每一回驗證:儲存模型為'resnet50_best.pth'

### Function - One Epoch Valid
def val_one_epoch(val_data_loader, best_val_acc):
    
    ### Local Parameters
    epoch_loss = []
    epoch_acc = []
    start_time = time.time()
    
    ###Iterating over data loader
    for images, labels in val_data_loader:
        
        #Loading images and labels to device
        images = images.to(device)
        labels = labels.to(device)
        labels = labels.reshape((labels.shape[0], 1)) # [N, 1] - to match with preds shape
        
        #Forward
        preds = model(images)
        
        #Calculating Loss
        _loss = criterion(preds, labels)
        loss = _loss.item()
        epoch_loss.append(loss)
        
        #Calculating Accuracy
        acc = accuracy(preds, labels)
        epoch_acc.append(acc)
    
    ###Overall Epoch Results
    end_time = time.time()
    total_time = end_time - start_time
    
    ###Acc and Loss
    epoch_loss = np.mean(epoch_loss)
    epoch_acc = np.mean(epoch_acc)
    
    ###Storing results to logs
    val_logs["loss"].append(epoch_loss)
    val_logs["accuracy"].append(epoch_acc)
    val_logs["time"].append(total_time)
    
    ###Saving best model
    if epoch_acc > best_val_acc:
        best_val_acc = epoch_acc
        torch.save(model.state_dict(),"resnet50_best.pth")
        
    return epoch_loss, epoch_acc, total_time, best_val_acc

Part 12.ResNet50 Pretrained Model

在kaggle,適用python 3.7。

model = resnet50(pretrained = True)

在本地端我是用python3.9.7。

from torchvision.models import ResNet50_Weights
model = resnet50(weights=ResNet50_Weights.DEFAULT)

設定訓練的Sequential model:

# Modifying Head - classifier

model.fc = nn.Sequential(
    nn.Linear(2048, 1, bias = True),
    nn.Sigmoid()
)

Part 13.設定模型參數

# Optimizer
optimizer = torch.optim.Adam(model.parameters(), lr = 0.0001)

# Learning Rate Scheduler
# 每次 step_size epochs 衰減每個參數組的學習率。
lr_scheduler = torch.optim.lr_scheduler.StepLR(optimizer, step_size = 5, gamma = 0.5)

#Loss Function
criterion = nn.BCELoss() #二元交叉熵損失函數

# Logs - Helpful for plotting after training finishes
train_logs = {"loss" : [], "accuracy" : [], "time" : []}
val_logs = {"loss" : [], "accuracy" : [], "time" : []}

# Loading model to device
model.to(device)

# No of epochs 
epochs = 20

Part 14. Train and Valid Model

### Training and Validation xD
best_val_acc = 0
for epoch in range(epochs):
    
    ###Training
    loss, acc, _time = train_one_epoch(train_data_loader)
    
    #Print Epoch Details
    print("\nTraining")
    print("Epoch {}".format(epoch+1))
    print("Loss : {}".format(round(loss, 4)))
    print("Acc : {}".format(round(acc, 4)))
    print("Time : {}".format(round(_time, 4)))
    
    ###Validation
    loss, acc, _time, best_val_acc = val_one_epoch(val_data_loader, best_val_acc)
    
    #Print Epoch Details
    print("\nValidating")
    print("Epoch {}".format(epoch+1))
    print("Loss : {}".format(round(loss, 4)))
    print("Acc : {}".format(round(acc, 4)))
    print("Time : {}".format(round(_time, 4)))

"
Training
Epoch 1
Loss : 0.0662
Acc : 97.8296
Time : 5253.6753

Validating
Epoch 1
Loss : 0.0464
Acc : 98.3216
Time : 736.903

Training
Epoch 2
Loss : 0.0358
Acc : 98.7948
Time : 4882.465

Validating
Epoch 2
Loss : 0.0312
Acc : 98.7852
Time : 638.738

Training
Epoch 3
Loss : 0.0278
Acc : 98.9814
Time : 4885.1015

Validating
Epoch 3
Loss : 0.0273
Acc : 98.913
Time : 629.354

Training
Epoch 4
Loss : 0.0218
Acc : 99.2854
Time : 4925.169

Validating
Epoch 4
Loss : 0.0348
Acc : 98.6733
Time : 632.915

Training
Epoch 5
Loss : 0.0229
Acc : 99.1841
Time : 5086.6376

Validating
Epoch 5
Loss : 0.0267
Acc : 98.8811
Time : 591.848

Training
Epoch 6
Loss : 0.0183
Acc : 99.3494
Time : 4841.4826

Validating
Epoch 6
Loss : 0.0324
Acc : 98.8811
Time : 628.952

Training
Epoch 7
Loss : 0.0155
Acc : 99.4294
Time : 4824.0096

Validating
Epoch 7
Loss : 0.0315
Acc : 98.7532
Time : 615.423

Training
Epoch 8
Loss : 0.0202
Acc : 99.3113
Time : 4763.0

Validating
Epoch 8
Loss : 0.0273
Acc : 98.8811
Time : 613.794

Training
Epoch 9
Loss : 0.0159
Acc : 99.4294
Time : 4748.983

Validating
Epoch 9
Loss : 0.0323
Acc : 98.913
Time : 615.81

Training
Epoch 10
Loss : 0.0117
Acc : 99.6054
Time : 4762.96

Validating
Epoch 10
Loss : 0.039
Acc : 98.4974
Time : 615.812

Training
Epoch 11
Loss : 0.0137
Acc : 99.5787
Time : 4756.948

Validating
Epoch 11
Loss : 0.0305
Acc : 99.0249
Time : 613.552

Training
Epoch 12
Loss : 0.0129
Acc : 99.5627
Time : 4765.72

Validating
Epoch 12
Loss : 0.0401
Acc : 98.5934
Time : 615.958

Training
Epoch 13
Loss : 0.0119
Acc : 99.6054
Time : 4779.163

Validating
Epoch 13
Loss : 0.0311
Acc : 98.913
Time : 613.923

Training
Epoch 14
Loss : 0.0124
Acc : 99.5627
Time : 6105.9822

Validating
Epoch 14
Loss : 0.0354
Acc : 98.8331
Time : 912.4271

Training
Epoch 15
Loss : 0.0116
Acc : 99.6054
Time : 6537.8869

Validating
Epoch 15
Loss : 0.0249
Acc : 99.009
Time : 918.9861

Training
Epoch 16
Loss : 0.01
Acc : 99.728
Time : 6638.2821

Validating
Epoch 16
Loss : 0.0395
Acc : 98.5934
Time : 824.718

Training
Epoch 17
Loss : 0.0107
Acc : 99.632
Time : 6624.546

Validating
Epoch 17
Loss : 0.04
Acc : 98.6893
Time : 934.2406

Training
Epoch 18
Loss : 0.018
Acc : 99.5094
Time : 5312.4133

Validating
Epoch 18
Loss : 0.0342
Acc : 98.7276
Time : 621.479

Training
Epoch 19
Loss : 0.0085
Acc : 99.7014
Time : 5512.1889

Validating
Epoch 19
Loss : 0.0356
Acc : 98.7852
Time : 647.4116

Training
Epoch 20
Loss : 0.0095
Acc : 99.6907
Time : 6281.2117

Validating
Epoch 20
Loss : 0.0563
Acc : 98.7372
Time : 790.0679
"

Part 15.Plot Results

### Plotting Results

#Loss
plt.title("Loss")
plt.plot(np.arange(1, 21, 1), train_logs["loss"], color = 'blue')
plt.plot(np.arange(1, 21, 1), val_logs["loss"], color = 'yellow')
plt.xlabel("Epochs")
plt.ylabel("Loss")
plt.show()

#Accuracy
plt.title("Accuracy")
plt.plot(np.arange(1, 21, 1), train_logs["accuracy"], color = 'blue')
plt.plot(np.arange(1, 21, 1), val_logs["accuracy"], color = 'yellow')
plt.xlabel("Epochs")
plt.ylabel("Accuracy")
plt.show()