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Principal component analysis

As explained in Graph Neural Networks in Action

Principal component analysis is a statistical dimensionality-reduction technique that transforms correlated variables into a smaller set of ordered orthogonal components.

Principal component analysis (PCA) reduces high-dimensional numerical descriptions into a smaller, fixed-length feature representation. In graph-learning workflows, it turns product text features into compact node inputs while preserving a practical representation for downstream models. section 3.5

A typical feature-construction pipeline is:

  • Convert product-description strings into numerical values with the bag-of-words algorithm. section 3.5
  • Apply PCA to convert the resulting representation into a vector of length 100. section 5.2.1 section 3.5
  • Use the reduced vectors as node features alongside product categories and co-purchase edges. section 3.5

Amazon Products

The Amazon Products dataset applies PCA after bag-of-words processing, giving every product 100 features. These features support graph tasks such as product categorization and link prediction, where nodes represent products and edges represent co-purchases. section 5.2.1 section 3.5

How Graph Neural Networks in Action covers it

How deep it goes
Explains PCA through its placement after bag-of-words and stops short of deriving the transformation mathematically.
Examples
Uses Amazon product descriptions, co-purchasing graphs, 100-feature vectors, product categorization, and link prediction.
What it assumes
Assumes numerical features can be created from text and teaches PCA as the next dimensionality-reduction step.
What you can do after
Apply it via a preprocessing pipeline that converts bag-of-words product descriptions into 100-feature node representations.
How it connects
Connects PCA to dimensionality reduction, bag-of-words, natural language processing, node features, and graph learning.

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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.