Feature hashing

Sat, 18 Jul 2026 09:58:07 +0000

Definition

Feature hashing, also known as the hashing trick, allows machine learning models to handle large, sparse feature spaces without maintaining an explicit mapping between features and indices. By applying a hash function to each feature, it deterministically assigns them to a fixed number of buckets. This reduces memory usage and eliminates the need for preprocessing steps like vocabulary building, making it highly efficient for text classification and recommendation systems with massive input dimensions.

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Feature hashing

Definition