Quick Start with PyTorch: Tensor Dimension Transformation and Common Operations
This article introduces the core knowledge of PyTorch tensors, including basics, dimension transformations, common operations, and exercise suggestions. Tensors are the basic structure for storing data in PyTorch, similar to NumPy arrays, and support GPU acceleration and automatic differentiation. They can be created using `torch.tensor()` from lists/numbers, `torch.from_numpy()` from NumPy arrays, or built-in functions to generate tensors of all zeros, ones, or random values. Dimension transformation is a key operation: `reshape()` flexibly adjusts the shape (keeping the total number of elements unchanged), `squeeze()` removes singleton dimensions, `unsqueeze()` adds singleton dimensions, and `transpose()`/`permute()` swap dimensions. Common operations include basic arithmetic operations, matrix multiplication with `matmul()`, broadcasting (automatic dimension expansion for operations), and aggregation operations such as `sum()`, `mean()`, and `max()`. The article suggests consolidating tensor operations through exercises, such as dimension adjustment, broadcasting mechanisms, and dimension swapping, to master the "shape language" and lay a foundation for subsequent model construction.
Read MorePyTorch Beginner's Guide: Understanding Model Construction with Simple Examples
This PyTorch beginner's tutorial covers core knowledge points: PyTorch is Python-based with obvious advantages in dynamic computation graphs and simple installation (`pip install torch`). The core data structure is the Tensor, which supports GPU acceleration, and can be created, manipulated (addition, subtraction, multiplication, division, matrix multiplication), and converted to/from NumPy. Automatic differentiation (autograd) is implemented via `requires_grad=True` for gradient calculation, e.g., the derivative of \( y = x^2 + 3x \) at \( x = 2 \) is 7. A linear regression model inherits `nn.Module` for definition, with forward propagation implementing \( y = wx + b \). For data preparation, simulated data (\( y = 2x + 3 + \text{noise} \)) is generated, and batched loaded using `TensorDataset` and `DataLoader`. Training uses MSE loss and SGD optimizer, with gradient zeroing, backpropagation, and parameter updates in the loop. After 1000 epochs, results are validated and visualized, with learned parameters close to the true values. The core process covers tensor operations, automatic differentiation, model construction, data loading, and training optimization, enabling scalability to complex models.
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