MLOps Prototyping

Goal

To create standardized, reproducible, and production-ready prototypes in Jupyter notebooks. This skill enforces a structured layout (Imports -> Configs -> Load -> EDA -> Modeling -> Eval) and robust engineering practices (Pipelines, Split-Verification) to prevent technical debt and data leakage.

Prerequisites

• Language: Python
• Environment: uv managed project (.venv)
• Context: Executed within a .ipynb file or converting to one.

Instructions

1. Notebook Structure

Enforce the following linear sections in every notebook to ensure readability and maintainability.

1. Title & Purpose: H1 Title and a brief description of the experiment goals.
2. Imports: Group standard libraries, third-party, and usage-specific imports.
3. Configs: Define Global Constants (paths, random seeds, hyperparameters) here. No magic numbers deeper in the code.
4. Datasets: Load, validate, and split data.
5. Analysis (EDA): Inspect target distributions and correlations.
6. Modeling: Define and train sklearn.pipeline.Pipeline objects.
7. Evaluations: Compute metrics and visualize performance on held-out data.

2. Configuration Standards

Expose all "knobs" at the top of the notebook for easy experimentation.

• Randomness: Define RANDOM_STATE = 42 and use it in splits and model initialization.

• Paths: Use pathlib for robust path handling.

  from pathlib import Path
  ROOT = Path("..")
  DATA_PATH = ROOT / "data" / "input.parquet"
  

• Hyperparameters: Group model params (e.g., N_ESTIMATORS, MAX_DEPTH).

• Toggles: Use booleans for expensive operations (e.g., USE_GPU = True, RUN_GRID_SEARCH = False).

3. Data Management

Ensure data integrity and prevent leakage.

• Loading: Prefer pd.read_parquet for speed/types, or pd.read_csv.
• Splitting:
  • Always split into X_train, X_test, y_train, y_test before any data-dependent transformations (imputation, scaling).
  • Random Split: Use sklearn.model_selection.train_test_split with stratify for balanced classification.
  • Time Series: Use sklearn.model_selection.TimeSeriesSplit if data has a temporal dimension (do NOT shuffle).
  • Use random_state=RANDOM_STATE.

4. Pipeline Construction

Prohibit raw data transformations on the full dataset.

• Mandate: Use sklearn.pipeline.Pipeline or ColumnTransformer.

• Why: Automation of fit on train and transform on test prevents data leakage.

• Example:

  from sklearn.pipeline import Pipeline
  from sklearn.preprocessing import StandardScaler, OneHotEncoder
  from sklearn.impute import SimpleImputer
  from sklearn.compose import ColumnTransformer
  
  CACHE = "./.cache" # Define a cache directory
  
  numeric_transformer = Pipeline(steps=[
      ('imputer', SimpleImputer(strategy='median')),
      ('scaler', StandardScaler())
  ])
  
  preprocessor = ColumnTransformer(transformers=[
      ('num', numeric_transformer, numeric_features)
  ])
  
  # Use 'memory' to cache transformer outputs, speeding up GridSearch
  model = Pipeline(steps=[
      ('preprocessor', preprocessor),
      ('classifier', RandomForestClassifier())
  ], memory=CACHE)
  

5. Evaluation & Visualization

Go beyond accuracy/MSE.

• Metrics: Use sklearn.metrics appropriate for the task (F1, ROC-AUC, RMSE, MAE).
• Baselines: Compare against a "Dummy" model (mean/mode) to verify learning.
• Visualization:
  • Regression: Residual plots, Actual vs Predicted.
  • Classification: Confusion Matrix, ROC Curve, Precision-Recall.
  • Feature Importance: Visualize feature_importances_ or SHAP values.

6. Transition to Production

Facilitate the move from notebook to python package (src/).

• Function Refactoring: Once a block of code is stable (e.g., a complex data cleaning step), refactor it into a function within the notebook. This makes moving it to a .py file trivial later.
• Cell Tagging: Use tags like parameters (for Papermill) or export to mark cells that should be part of the final documentation or automated pipeline.
• Clean State: Ensure the notebook runs top-to-bottom (Restart Kernel and Run All) without errors before committing.

Self-Correction Checklist

• No Magic Numbers: Are all parameters in the Configs section?
• No Data Leakage: Is fit called ONLY on X_train?
• Reproducibility: Is random_state set for all stochastic operations?
• Resilience: are paths defined relative to the project root?
• Clarity: Does the notebook read like a report (Markdown cells explaining the Why)?