train_nin.py

#imports

import os
import csv
import torch
from torch import nn 
from torch.utils.data import DataLoader 
from torchvision import datasets 
from torchvision.transforms import ToTensor, Normalize, RandomCrop, RandomHorizontalFlip, Compose 
from contextualizer_nin import ContextualizerNiN

# data transforms

transform = Compose([
RandomCrop(32, padding=4),
RandomHorizontalFlip(), 
ToTensor(),
Normalize((0.5, 0.5,0.5),(0.5, 0.5,0.5))

])

training_data = datasets.CIFAR10(
                                       root='data',
                                       train=True,
                                       download=True,
                                       transform=transform 
                                       )

test_data = datasets.CIFAR10(
                                       root='data',
                                       train=False,
                                       download=True,
                                       transform=transform 
                                       )                                       
# create dataloaders  
                                     
batch_size = 128

train_dataloader = DataLoader(training_data, batch_size=batch_size,shuffle=True)
test_dataloader = DataLoader(test_data, batch_size=batch_size)


for X, y in test_dataloader:
    print(f"Shape of X [N,C,H,W]:{X.shape}")
    print(f"Shape of y:{y.shape}{y.dtype}")
    break

# size checking for loading images
def check_sizes(image_size, patch_size):
    sqrt_num_patches, remainder = divmod(image_size, patch_size)
    assert remainder == 0, "`image_size` must be divisibe by `patch_size`"
    num_patches = sqrt_num_patches ** 2
    return num_patches



# create model
# Get cpu or gpu device for training.
device = "cuda" if torch.cuda.is_available() else "cpu"

print(f"using {device} device") 

# model definition

class ContextualizerNiNImageClassification(ContextualizerNiN):
    def __init__(
        self,
        image_size=32,
        patch_size=4,
        in_channels=3,
        num_classes=10,
        d_ffn=512,
        d_model = 256,
        num_tokens = 64,
        num_layers=4,
        dropout=0.5
    ):
        num_patches = check_sizes(image_size, patch_size)
        super().__init__(d_model,d_ffn,num_layers,dropout, num_tokens)
        self.patcher = nn.Conv2d(
            in_channels, d_model, kernel_size=patch_size, stride=patch_size
        )
        self.classifier = nn.Linear(d_model, num_classes)

    def forward(self, x):
        
        patches = self.patcher(x)
        batch_size, num_channels, _, _ = patches.shape
        patches = patches.permute(0, 2, 3, 1)
        patches = patches.view(batch_size, -1, num_channels)
        embedding = self.model(patches)
        embedding = embedding.mean(dim=1) # global average pooling
        out = self.classifier(embedding)
        return out

model = ContextualizerNiNImageClassification().to(device)
print(model)

# Optimizer

loss_fn = nn.CrossEntropyLoss()
optimizer = torch.optim.Adam(model.parameters(),lr=1e-3)


# Training Loop

def train(dataloader, model, loss_fn, optimizer):
    size = len(dataloader.dataset)
    num_batches = len(dataloader)
    model.train()
    train_loss = 0
    correct = 0
    for batch, (X,y) in enumerate(dataloader):
        X, y = X.to(device), y.to(device)
       
        #compute prediction error
        pred = model(X)
        loss = loss_fn(pred,y)
        
        # backpropagation
        optimizer.zero_grad()
        loss.backward()
        optimizer.step()
        train_loss += loss.item()
        _, labels = torch.max(pred.data, 1)
        correct += labels.eq(y.data).type(torch.float).sum()

        


        if batch % 100 == 0:
            loss, current = loss.item(), batch * len(X)
            print(f"loss: {loss:>7f}   [{current:>5d}/{size:>5d}]")

    train_loss /= num_batches
    train_accuracy = 100. * correct.item() / size
    print(train_accuracy)
    return train_loss,train_accuracy 



# Test loop

def test(dataloader, model, loss_fn):
    size = len(dataloader.dataset)            
    num_batches = len(dataloader)
    model.eval()
    test_loss = 0
    correct = 0
    with torch.no_grad():
        for X,y in dataloader:
            X,y = X.to(device), y.to(device)
            pred = model(X)
            test_loss += loss_fn(pred, y).item()
            correct += (pred.argmax(1) == y).type(torch.float).sum().item()
    test_loss /= num_batches
    correct /= size
    print(f"Test Error: \n Accuracy: {(100*correct):>0.1f}%, Avg loss: {test_loss:>8f} \n")  
    test_accuracy = 100*correct      
    return test_loss, test_accuracy



# apply train and test

logname = "/PATH/Contextualizer_NiN/Experiments_cifar10/logs_contextualizer/logs_cifar10.csv"
if not os.path.exists(logname):
  with open(logname, 'w') as logfile:
    logwriter = csv.writer(logfile, delimiter=',')
    logwriter.writerow(['epoch', 'train loss', 'train acc',
                        'test loss', 'test acc'])


epochs = 100
for epoch in range(epochs):
    print(f"Epoch {epoch+1}\n-----------------------------------")
    train_loss, train_acc = train(train_dataloader, model, loss_fn, optimizer)
    # learning rate scheduler
    #if scheduler is not None:
    #    scheduler.step()
    test_loss, test_acc = test(test_dataloader, model, loss_fn)
    with open(logname, 'a') as logfile:
        logwriter = csv.writer(logfile, delimiter=',')
        logwriter.writerow([epoch+1, train_loss, train_acc,
                            test_loss, test_acc])
print("Done!")

# saving trained model

path = "/PATH/Contextualizer_NiN/Experiments_cifar10/weights_contextualizer"
model_name = "ContextualizerNiNImageClassification_cifar10"
torch.save(model.state_dict(), f"{path}/{model_name}.pth")
print(f"Saved Model State to {path}/{model_name}.pth ")