RECO ENGINE
Collaborative filtering and matrix factorization that rank listings by user behavior — converting what users do into ranking logic they can act on.
ORGANIZATION
INDEPENDENT BUILD
PERIOD
2024 — 2025
ROLE
MODELING & RANKING LOGIC — SOLO
STACK
SCIKIT-LEARN · PANDAS
01 — THE BRIEF
Users tell you what they want through behavior long before they'd articulate it in a search filter. The problem is turning scattered interactions into an ordering that's actually useful.
The Reco Engine does that with proven recommendation math: collaborative filtering and matrix factorization over user-behavior data, producing ranked listings instead of an unordered pile.
02 — OPERATING CONSTRAINTS
- Behavior data is sparse — most users touch few listings, so the model must generalize from little signal.
- The output had to be ranking logic a product can act on, not a research notebook.
- Interpretable, tunable methods over black-box novelty.
03 — SYSTEM STRUCTURE
BEHAVIOR DATA PREP
Pandas — user-listing interactions structured into matrices the models can learn from.
COLLABORATIVE FILTERING
Users who behave alike predict each other's interests.
MATRIX FACTORIZATION
Scikit-learn — latent factors filling the gaps sparse behavior leaves behind.
RANKED OUTPUT
An ordered listing feed — ranking logic, ready for a product surface.
04 — KEY DECISIONS
DECISION 01
Proven math over fashionable models
Collaborative filtering and matrix factorization are the recommendation industry's load-bearing walls — understood, tunable, and defensible in review.
DECISION 02
Behavior over declared preference
What users click outranks what they say — the engine learns from actions.
DECISION 03
Ship ranking logic, not a paper
The deliverable is an ordering a product can use — decision output, same as every build in this file.
05 — OUTCOME
Behavior data became ranking logic users can act on.
- · Pairs with Exhibit E — clean listings in, personalized ordering out.
CROSS-EXAMINATION
The full walkthrough — code, schema, trade-offs — happens live. Fifteen minutes, no slides.
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