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ToSparseTensor

As explained in Graph Neural Networks in Action

ToSparseTensor is a PyTorch Geometric transformation that converts graph adjacency data into a sparse tensor representation.

ToSparseTensor converts a dense adjacency matrix or edge index into a sparse tensor in PyTorch Geometric. It is useful when large graphs contain many absent edges, because sparse storage can reduce memory use. section 7.5

Use the transformation as a short data-processing pipeline:

  • Create or load a graph dataset containing dense adjacency data or an edge index. section 7.5
  • Attach ToSparseTensor() as the dataset transform to construct a COO-format sparse adjacency matrix. section 7.5
  • Prefer dense storage when few adjacency entries are zero or sparse indexing overhead outweighs memory savings. section 7.5

Campus social network

Represent students as nodes and associations as edges in a multi-campus social graph, then convert its adjacency data to a sparse tensor when most possible associations are absent. section 7.5

torch_geometric.transforms import ToSparseTensor

dataset = YourDataset(transform=ToSparseTensor())

View the minimal PyG dataset configuration that applies ToSparseTensor during loading. section 7.5

How Graph Neural Networks in Action covers it

How deep it goes
Explains dense-to-sparse conversion and COO construction, while deferring detailed sparse-format mechanics to another reference.
Examples
Uses a student social network spanning multiple campuses to motivate sparse adjacency storage.
What it assumes
Assumes basic graph adjacency data and distinguishes sparse graphs from dense tensor representations.
What you can do after
Apply it via PyTorch Geometric to convert graph adjacency data into COO sparse tensors.
How it connects
Connects adjacency matrices, edge indices, COO format, sparse tensors, dense representation, PyTorch, and SciPy.

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Graph Neural Networks in Action. The section links point to the parts of the book it draws on.