new help_funcs

Co-Authored-By: Ranuga <[email protected]>

Author: Programmer-RD-AI

__pycache__/helper_functions.cpython-38.pyc

@@ -0,0 +1,294 @@
+"""
+A series of helper functions used throughout the course.
+
+If a function gets defined once and could be used over and over, it'll go in here.
+"""
+import torch
+import matplotlib.pyplot as plt
+import numpy as np
+
+from torch import nn
+
+import os
+import zipfile
+
+from pathlib import Path
+
+import requests
+
+# Walk through an image classification directory and find out how many files (images)
+# are in each subdirectory.
+import os
+
+def walk_through_dir(dir_path):
+    """
+    Walks through dir_path returning its contents.
+    Args:
+    dir_path (str): target directory
+
+    Returns:
+    A print out of:
+      number of subdiretories in dir_path
+      number of images (files) in each subdirectory
+      name of each subdirectory
+    """
+    for dirpath, dirnames, filenames in os.walk(dir_path):
+        print(f"There are {len(dirnames)} directories and {len(filenames)} images in '{dirpath}'.")
+
+def plot_decision_boundary(model: torch.nn.Module, X: torch.Tensor, y: torch.Tensor):
+    """Plots decision boundaries of model predicting on X in comparison to y.
+
+    Source - https://madewithml.com/courses/foundations/neural-networks/ (with modifications)
+    """
+    # Put everything to CPU (works better with NumPy + Matplotlib)
+    model.to("cpu")
+    X, y = X.to("cpu"), y.to("cpu")
+
+    # Setup prediction boundaries and grid
+    x_min, x_max = X[:, 0].min() - 0.1, X[:, 0].max() + 0.1
+    y_min, y_max = X[:, 1].min() - 0.1, X[:, 1].max() + 0.1
+    xx, yy = np.meshgrid(np.linspace(x_min, x_max, 101), np.linspace(y_min, y_max, 101))
+
+    # Make features
+    X_to_pred_on = torch.from_numpy(np.column_stack((xx.ravel(), yy.ravel()))).float()
+
+    # Make predictions
+    model.eval()
+    with torch.inference_mode():
+        y_logits = model(X_to_pred_on)
+
+    # Test for multi-class or binary and adjust logits to prediction labels
+    if len(torch.unique(y)) > 2:
+        y_pred = torch.softmax(y_logits, dim=1).argmax(dim=1)  # mutli-class
+    else:
+        y_pred = torch.round(torch.sigmoid(y_logits))  # binary
+
+    # Reshape preds and plot
+    y_pred = y_pred.reshape(xx.shape).detach().numpy()
+    plt.contourf(xx, yy, y_pred, cmap=plt.cm.RdYlBu, alpha=0.7)
+    plt.scatter(X[:, 0], X[:, 1], c=y, s=40, cmap=plt.cm.RdYlBu)
+    plt.xlim(xx.min(), xx.max())
+    plt.ylim(yy.min(), yy.max())
+
+
+# Plot linear data or training and test and predictions (optional)
+def plot_predictions(
+    train_data, train_labels, test_data, test_labels, predictions=None
+):
+    """
+  Plots linear training data and test data and compares predictions.
+  """
+    plt.figure(figsize=(10, 7))
+
+    # Plot training data in blue
+    plt.scatter(train_data, train_labels, c="b", s=4, label="Training data")
+
+    # Plot test data in green
+    plt.scatter(test_data, test_labels, c="g", s=4, label="Testing data")
+
+    if predictions is not None:
+        # Plot the predictions in red (predictions were made on the test data)
+        plt.scatter(test_data, predictions, c="r", s=4, label="Predictions")
+
+    # Show the legend
+    plt.legend(prop={"size": 14})
+
+
+# Calculate accuracy (a classification metric)
+def accuracy_fn(y_true, y_pred):
+    """Calculates accuracy between truth labels and predictions.
+
+    Args:
+        y_true (torch.Tensor): Truth labels for predictions.
+        y_pred (torch.Tensor): Predictions to be compared to predictions.
+
+    Returns:
+        [torch.float]: Accuracy value between y_true and y_pred, e.g. 78.45
+    """
+    correct = torch.eq(y_true, y_pred).sum().item()
+    acc = (correct / len(y_pred)) * 100
+    return acc
+
+
+def print_train_time(start, end, device=None):
+    """Prints difference between start and end time.
+
+    Args:
+        start (float): Start time of computation (preferred in timeit format). 
+        end (float): End time of computation.
+        device ([type], optional): Device that compute is running on. Defaults to None.
+
+    Returns:
+        float: time between start and end in seconds (higher is longer).
+    """
+    total_time = end - start
+    print(f"\nTrain time on {device}: {total_time:.3f} seconds")
+    return total_time
+
+
+# Plot loss curves of a model
+def plot_loss_curves(results):
+    """Plots training curves of a results dictionary.
+
+    Args:
+        results (dict): dictionary containing list of values, e.g.
+            {"train_loss": [...],
+             "train_acc": [...],
+             "test_loss": [...],
+             "test_acc": [...]}
+    """
+    loss = results["train_loss"]
+    test_loss = results["test_loss"]
+
+    accuracy = results["train_acc"]
+    test_accuracy = results["test_acc"]
+
+    epochs = range(len(results["train_loss"]))
+
+    plt.figure(figsize=(15, 7))
+
+    # Plot loss
+    plt.subplot(1, 2, 1)
+    plt.plot(epochs, loss, label="train_loss")
+    plt.plot(epochs, test_loss, label="test_loss")
+    plt.title("Loss")
+    plt.xlabel("Epochs")
+    plt.legend()
+
+    # Plot accuracy
+    plt.subplot(1, 2, 2)
+    plt.plot(epochs, accuracy, label="train_accuracy")
+    plt.plot(epochs, test_accuracy, label="test_accuracy")
+    plt.title("Accuracy")
+    plt.xlabel("Epochs")
+    plt.legend()
+
+
+# Pred and plot image function from notebook 04
+# See creation: https://www.learnpytorch.io/04_pytorch_custom_datasets/#113-putting-custom-image-prediction-together-building-a-function
+from typing import List
+import torchvision
+
+
+def pred_and_plot_image(
+    model: torch.nn.Module,
+    image_path: str,
+    class_names: List[str] = None,
+    transform=None,
+    device: torch.device = "cuda" if torch.cuda.is_available() else "cpu",
+):
+    """Makes a prediction on a target image with a trained model and plots the image.
+
+    Args:
+        model (torch.nn.Module): trained PyTorch image classification model.
+        image_path (str): filepath to target image.
+        class_names (List[str], optional): different class names for target image. Defaults to None.
+        transform (_type_, optional): transform of target image. Defaults to None.
+        device (torch.device, optional): target device to compute on. Defaults to "cuda" if torch.cuda.is_available() else "cpu".
+    
+    Returns:
+        Matplotlib plot of target image and model prediction as title.
+
+    Example usage:
+        pred_and_plot_image(model=model,
+                            image="some_image.jpeg",
+                            class_names=["class_1", "class_2", "class_3"],
+                            transform=torchvision.transforms.ToTensor(),
+                            device=device)
+    """
+
+    # 1. Load in image and convert the tensor values to float32
+    target_image = torchvision.io.read_image(str(image_path)).type(torch.float32)
+
+    # 2. Divide the image pixel values by 255 to get them between [0, 1]
+    target_image = target_image / 255.0
+
+    # 3. Transform if necessary
+    if transform:
+        target_image = transform(target_image)
+
+    # 4. Make sure the model is on the target device
+    model.to(device)
+
+    # 5. Turn on model evaluation mode and inference mode
+    model.eval()
+    with torch.inference_mode():
+        # Add an extra dimension to the image
+        target_image = target_image.unsqueeze(dim=0)
+
+        # Make a prediction on image with an extra dimension and send it to the target device
+        target_image_pred = model(target_image.to(device))
+
+    # 6. Convert logits -> prediction probabilities (using torch.softmax() for multi-class classification)
+    target_image_pred_probs = torch.softmax(target_image_pred, dim=1)
+
+    # 7. Convert prediction probabilities -> prediction labels
+    target_image_pred_label = torch.argmax(target_image_pred_probs, dim=1)
+
+    # 8. Plot the image alongside the prediction and prediction probability
+    plt.imshow(
+        target_image.squeeze().permute(1, 2, 0)
+    )  # make sure it's the right size for matplotlib
+    if class_names:
+        title = f"Pred: {class_names[target_image_pred_label.cpu()]} | Prob: {target_image_pred_probs.max().cpu():.3f}"
+    else:
+        title = f"Pred: {target_image_pred_label} | Prob: {target_image_pred_probs.max().cpu():.3f}"
+    plt.title(title)
+    plt.axis(False)
+
+def set_seeds(seed: int=42):
+    """Sets random sets for torch operations.
+
+    Args:
+        seed (int, optional): Random seed to set. Defaults to 42.
+    """
+    # Set the seed for general torch operations
+    torch.manual_seed(seed)
+    # Set the seed for CUDA torch operations (ones that happen on the GPU)
+    torch.cuda.manual_seed(seed)
+
+def download_data(source: str, 
+                  destination: str,
+                  remove_source: bool = True) -> Path:
+    """Downloads a zipped dataset from source and unzips to destination.
+
+    Args:
+        source (str): A link to a zipped file containing data.
+        destination (str): A target directory to unzip data to.
+        remove_source (bool): Whether to remove the source after downloading and extracting.
+    
+    Returns:
+        pathlib.Path to downloaded data.
+    
+    Example usage:
+        download_data(source="https://github.com/mrdbourke/pytorch-deep-learning/raw/main/data/pizza_steak_sushi.zip",
+                      destination="pizza_steak_sushi")
+    """
+    # Setup path to data folder
+    data_path = Path("data/")
+    image_path = data_path / destination
+
+    # If the image folder doesn't exist, download it and prepare it... 
+    if image_path.is_dir():
+        print(f"[INFO] {image_path} directory exists, skipping download.")
+    else:
+        print(f"[INFO] Did not find {image_path} directory, creating one...")
+        image_path.mkdir(parents=True, exist_ok=True)
+        
+        # Download pizza, steak, sushi data
+        target_file = Path(source).name
+        with open(data_path / target_file, "wb") as f:
+            request = requests.get(source)
+            print(f"[INFO] Downloading {target_file} from {source}...")
+            f.write(request.content)
+
+        # Unzip pizza, steak, sushi data
+        with zipfile.ZipFile(data_path / target_file, "r") as zip_ref:
+            print(f"[INFO] Unzipping {target_file} data...") 
+            zip_ref.extractall(image_path)
+
+        # Remove .zip file
+        if remove_source:
+            os.remove(data_path / target_file)
+    
+    return image_path