[{"_1":2,"_3":-5,"_4":-5},"loaderData",{"_5":6,"_7":8},"actionData","errors","root",{"_28":-5,"_38":-5,"_39":40,"_41":42,"_43":44,"_45":46,"_47":48,"_49":50,"_51":52,"_53":54,"_55":56,"_57":58},"routes/_store+/_readers+/email_author.$slug/route",{"_9":10,"_11":-5},"book",{"_12":13,"_14":15,"_16":17,"_18":19,"_20":21,"_22":23},"currentUser","id","Z2lkOi8vbGVhbnB1Yi9TdG9yZTo6Qm9va1Byb2R1Y3QvODMxNzU","title","Semantic Search from Scratch","state","published","contactAuthorMethod","email","aboutText","

Modern AI systems retrieve information by meaning rather than exact keyword matches. Under the hood, this capability relies on a surprisingly simple foundation: representing text as vectors, measuring similarity, and ranking results.

In Semantic Search from Scratch, you will build this core mechanism yourself from first principles using only Python and NumPy.

We deliberately avoid third-party vector databases, machine-learning frameworks, and high-level retrieval libraries. The goal isn't to build a production platform, but to demystify the mathematical mechanics behind semantic retrieval, vector spaces, and Retrieval-Augmented Generation (RAG).

What You Will Learn & Build:

Vectors as Representations: Understand how natural language transforms into dense numerical representations.
Mathematical Similarity: Implement Cosine Similarity from scratch using raw matrix operations.
Document Indexing: Construct a complete educational vector index to store and query text representations.
Top-K Retrieval & Ranking: Build a scoring loop that ranks contextually relevant documents for downstream AI prompts.
RAG Foundations: Connect the dots between vector similarity and modern AI retrieval pipelines.

Who Is This Capsule For?

This guide is designed for intermediate Python developers, AI engineers, and curiosity-driven builders who want to peel back the layers of high-level AI libraries and truly understand how semantic search works under the hood.

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Kick off your book project, get started with GhostAI, get better at marketing, or spend the day doing all three! Free live workshops on Zoom. Saturday, June 27, 2026.

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