Add comments and docstrings to main.py and api.py

src/api.py

@@ -1,15 +1,22 @@
+"""
+This module is used to serve a PyTorch model as a FastAPI service. It includes the necessary steps to load the model, 
+preprocess the input image, and make a prediction.
+"""
+
 from fastapi import FastAPI, UploadFile, File
 from PIL import Image
 import torch
 from torchvision import transforms
 from main import Net  # Importing Net class from main.py
 
 # Load the model
+# The model is loaded from the saved state dictionary and set to evaluation mode.
 model = Net()
 model.load_state_dict(torch.load("mnist_model.pth"))
 model.eval()
 
 # Transform used for preprocessing the image
+# The transform is used to convert the input image to a tensor and normalize it.
 transform = transforms.Compose([
     transforms.ToTensor(),
     transforms.Normalize((0.5,), (0.5,))
@@ -19,10 +26,29 @@
 
 @app.post("/predict/")
 async def predict(file: UploadFile = File(...)):
+    """
+    This function takes an uploaded file as input, preprocesses the image, makes a prediction using the model, 
+    and returns the prediction.
+
+    Parameters:
+    file: The uploaded file containing the image.
+
+    Returns:
+    A dictionary containing the prediction made by the model.
+    """
+    # Open the image file and convert it to grayscale
     image = Image.open(file.file).convert("L")
+
+    # Preprocess the image using the transform
     image = transform(image)
+
+    # Add a batch dimension to the image
     image = image.unsqueeze(0)  # Add batch dimension
+
+    # Make a prediction using the model
     with torch.no_grad():
         output = model(image)
         _, predicted = torch.max(output.data, 1)
+
+    # Return the prediction
     return {"prediction": int(predicted[0])}

src/main.py

@@ -1,48 +1,87 @@
-from PIL import Image
+"""
+This module is used to train a PyTorch model on the MNIST dataset. It includes the necessary steps to preprocess the data,
+define the model, and train the model.
+"""
+
 import torch
 import torch.nn as nn
 import torch.optim as optim
-from torchvision import datasets, transforms
 from torch.utils.data import DataLoader
-import numpy as np
+from torchvision import datasets, transforms
 
 # Step 1: Load MNIST Data and Preprocess
-transform = transforms.Compose([
-    transforms.ToTensor(),
-    transforms.Normalize((0.5,), (0.5,))
-])
+# The transform variable is used to preprocess the MNIST data by converting the images to tensors and normalizing them.
+transform = transforms.Compose(
+    [transforms.ToTensor(), transforms.Normalize((0.5,), (0.5,))]
+)
 
-trainset = datasets.MNIST('.', download=True, train=True, transform=transform)
+trainset = datasets.MNIST(".", download=True, train=True, transform=transform)
 trainloader = DataLoader(trainset, batch_size=64, shuffle=True)
 
+
 # Step 2: Define the PyTorch Model
 class Net(nn.Module):
+    """
+    This class defines a simple feed-forward neural network for the MNIST dataset. It includes three fully connected layers.
+
+    Attributes:
+    fc1: The first fully connected layer.
+    fc2: The second fully connected layer.
+    fc3: The third fully connected layer.
+    """
+
     def __init__(self):
+        """
+        Initializes the Net class by defining the three fully connected layers.
+        """
         super().__init__()
         self.fc1 = nn.Linear(28 * 28, 128)
         self.fc2 = nn.Linear(128, 64)
         self.fc3 = nn.Linear(64, 10)
-    
+
     def forward(self, x):
+        """
+        Defines the forward pass of the network.
+
+        Parameters:
+        x: The input tensor.
+
+        Returns:
+        The output tensor after passing through the network.
+        """
         x = x.view(-1, 28 * 28)
         x = nn.functional.relu(self.fc1(x))
         x = nn.functional.relu(self.fc2(x))
         x = self.fc3(x)
         return nn.functional.log_softmax(x, dim=1)
 
+
 # Step 3: Train the Model
 model = Net()
 optimizer = optim.SGD(model.parameters(), lr=0.01)
 criterion = nn.NLLLoss()
 
 # Training loop
+# Define the number of training epochs
 epochs = 3
-for epoch in range(epochs):
+
+# Start the training loop
+for _ in range(epochs):
+    # For each batch of images and labels in the trainloader
     for images, labels in trainloader:
+        # Zero the gradients
         optimizer.zero_grad()
+
+        # Forward pass: compute the output of the model on the images
         output = model(images)
+
+        # Compute the loss between the output and the labels
         loss = criterion(output, labels)
+
+        # Backward pass: compute the gradients of the loss with respect to the model parameters
         loss.backward()
+
+        # Update the model parameters
         optimizer.step()
 
-torch.save(model.state_dict(), "mnist_model.pth")
+torch.save(model.state_dict(), "mnist_model.pth")