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Rossmann sales forecasting

A LightGBM pipeline for the Rossmann Kaggle competition, with log-transformed targets, Optuna tuning, and shared feature logic across notebooks.

2026PublishedLightGBM / Feature engineering / Kaggle
Measured signal0.1199held-out RMSPE
Measured signal49/56/63day windows
Measured signal3pipeline stages

01 / The problem

Retail sales are shaped by promotions, holidays, store characteristics, and temporal patterns. A notebook can produce a strong score while still making it easy to leak future information or mismatch predictions to rows.

02 / The approach

The project separates feature engineering, modeling, and inference, shares feature logic across stages, uses chronological validation, and keeps identifiers in the pipeline to avoid silent row mismatches.

03 / What shipped

  • Lag and rolling features with calendar, promotion, and competition signals
  • Log-transformed target with Optuna hyperparameter search
  • One shared feature implementation across train, validation, and inference
  • A reproducible notebook handoff through saved artifacts

04 / Outcome

It is a compact example of disciplined tabular ML: not the loudest project, but a useful baseline for showing how reliable experiments are assembled.

A clean experiment is one where the next person can tell exactly what happened.