early-stopping pytorch refs

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https://medium.com/@vrunda.bhattbhatt/a-step-by-step-guide-to-early-stopping-in-tensorflow-and-pytorch-59c1e3d0e376Step-by-Step Guide in PyTorch
1.Import libraries
import torch
import numpy as np
from torch import nn
from torch.nn import Conv2d, MaxPool2d, Upsample, Concatenate
from torch.optim import Adam
import copy
2. Define the U-Net Architecture

class UNet(nn.Module):
    def __init__(self, input_channels, output_channels):
        super(UNet, self).__init__()

        # Contracting path
        self.conv1 = Conv2d(input_channels, 64, 3, padding=1)
        self.conv2 = Conv2d(64, 64, 3, padding=1)
        self.pool = MaxPool2d(2, 2)
        self.conv3 = Conv2d(64, 128, 3, padding=1)
        self.conv4 = Conv2d(128, 128, 3, padding=1)
        self.conv5 = Conv2d(128, 256, 3, padding=1)
        self.conv6 = Conv2d(256, 256, 3, padding=1)

        # Expanding path
        self.up7 = Upsample(scale_factor=2, mode='bilinear', align_corners=True)
        self.conv7 = Conv2d(256, 128, 3, padding=1)
        self.conv8 = Conv2d(128, 128, 3, padding=1)
        self.up8 = Upsample(scale_factor=2, mode='bilinear', align_corners=True)
        self.conv9 = Conv2d(128, 64, 3, padding=1)
        self.conv10 = Conv2d(64, 64, 3, padding=1)

        # Output layer
        self.conv11 = nn.Conv2d(64, output_channels, 1)

    def forward(self, x):
        # Contracting path
        x1 = self.conv1(x)
        x1 = nn.functional.relu(x1)
        x1 = self.conv2(x1)
        x1 = nn.functional.relu(x1)
        x1 = self.pool(x1)
        x2 = self.conv3(x1)
        x2 = nn.functional.relu(x2)
        x2 = self.conv4(x2)
        x2 = nn.functional.relu(x2)
        x2 = self.pool(x2)
        x3 = self.conv5(x2)
        x3 = nn.functional.relu(x3)
        x3 = self.conv6(x3)
        x3 = nn.functional.relu(x3)

        # Expanding path
        x4 = self.up7(x3)
        x4 = torch.cat([x4, x2], dim=1)  # Skip connection
        x4 = self.conv7(x4)
        x4 = nn.functional.relu(x4)
        x4 = self.conv8(x4)
        x4 = nn.functional.relu(x4)
        x5 = self.up8(x4)
        x5 = torch.cat([x5, x1], dim=1)  # Skip connection
        x5 = self.conv9(x5)
        x5 = nn.functional.relu(x5)
        x5 = self.conv10(x5)
        x5 = nn.functional.relu(x5)

        # Output layer
        output = self.conv11(x5)
        return output
3. Load your data

X_train = torch.from_numpy(np.load('your_training_images.npy'))
y_train = torch.from_numpy(np.load('your_training_segmentations.npy'))
X_val = torch.from_numpy(np.load('your_validation_images
4. Define HyperParameters

input_channels = X_train.shape[1]  # Adjust based on your image channels
output_channels = 1  # For binary segmentation
5. Create UNet model

model = UNet(input_channels, output_channels)
6. Initialize Optimizer and Loss Functions

optimizer = Adam(model.parameters())
criterion = nn.BCELoss()
7. Training loop with early stopping

#Initialize Variables for EarlyStopping
best_loss = float('inf')
best_model_weights = None
patience = 10

# Training Loop with Early Stopping:**
for epoch in range(100):
    # Set model to training mode
    model.train()

    # Forward pass and loss calculation
    outputs = model(X_train)
    loss = criterion(outputs, y_train.float())  # Convert y_train to float for BCELoss

    # Backward pass and optimization
    optimizer.zero_grad()
    loss.backward()
    optimizer.step()

    # Validation
    model.eval()  # Set model to evaluation mode
    with torch.no_grad():  # Disable gradient calculation for validation
        val_outputs = model(X_val)
        val_loss = criterion(val_outputs, y_val.float())

    # Early stopping
    if val_loss < best_loss:
        best_loss = val_loss
        best_model_weights = copy.deepcopy(model.state_dict())  # Deep copy here      
        patience = 10  # Reset patience counter
    else:
        patience -= 1
        if patience == 0:
            break

# Load the best model weights
model.load_state_dict(best_model_weights)
8. Inference

# Set model to evaluation mode
model.eval()

# Perform inference on new images
with torch.no_grad():
    new_images = torch.from_numpy(np.load('your_new_images.npy'))
    predictions = model(new_images)

# Process and visualize predictions as needed```