churnlib is a small Python toolkit that helps data scientists run end‑to‑end customer churn analyses with just a few lines of code.

Customer churn is one of the most direct levers for sustainable growth: it impacts revenue predictability, customer lifetime value (CLV), and how efficiently you can spend on acquisition and retention.

A few practical reasons teams invest in churn analysis:

• Retention is usually cheaper than acquisition. HBR summarizes research suggesting acquiring a new customer can be 5–25× more expensive than retaining an existing one. :contentReference[oaicite:1]{index=1}
• Small retention gains can have outsized profit impact. HBR also cites work (Reichheld / Bain) often quoted as: improving retention by 5% can increase profits by 25%–95% (industry-dependent). :contentReference[oaicite:2]{index=2}
• Operational focus: churn analysis helps you identify who is at risk, why, and what intervention is worth it (discount vs. onboarding help vs. product fix).
• Better targeting: instead of blanket outreach, you can prioritize customers where preventing churn produces the highest incremental value (often via lift / gain style views).

Beyond a single churn rate, teams typically want:

• A clear label definition (what counts as churn, and over what horizon?)
• A time-aware split (to avoid leakage when customer behavior changes over time)
• ML metrics and business-facing views (e.g., lift tables / “top decile captures X% of churners”)
• Interpretability (which features drive risk) so the analysis leads to action

churnlib is designed to cover these basics end-to-end: preprocessing, baseline modeling, standard ML metrics, churn-specific business metrics + lift tables, and a lightweight HTML report you can share with stakeholders.

• Simple configuration via ChurnConfig
• Automatic train/test split (time‑based or random)
• Sensible preprocessing for numeric and categorical features
• Baseline model selection (logistic regression & gradient boosting)
• Standard ML metrics (AUC, PR‑AUC, F1, etc.)
• Churn‑specific business metrics and lift table
• Simple HTML report summarising configuration, performance, and top features

From the directory that contains pyproject.toml:

pip install -e .

This will install churnlib in editable mode so changes to the source are picked up immediately.

import pandas as pd
from churnlib import ChurnProject

df = pd.read_csv("your_customer_table.csv")

project = ChurnProject.from_dataframe(
    df,
    id_col="customer_id",
    label_col="churn",
    positive_label=1,   # or "Yes"
    date_col="snapshot_date",        # optional
    prediction_horizon_days=30,      # optional, for documentation
)

# Run the full workflow: split, preprocess, model selection, evaluation
results = project.auto_fit(df)

# Notebook‑friendly summary
print(project.summary())

# Generate a simple HTML report
project.report("churn_report.html")

# Score new customers
scoring_df = df.sample(100).copy()
scores = project.score(scoring_df)
print(scores.head())

Key dependencies (also listed in pyproject.toml):

• pandas
• scikit‑learn
• matplotlib (for optional plotting helpers)

pip install -e ".[dev]"
pytest