Python Data Analysis Toolkit

A production-ready Python library for data cleaning, anomaly detection, report generation, and SQL query analysis. Built on pandas and numpy, it provides typed, well-documented APIs suitable for pipelines, notebooks, and automated reporting workflows.

⚠️ Limitation: QueryOptimizer performs static heuristic analysis using regex patterns. It does not parse SQL with a full AST engine. Complex queries (nested CTEs, window functions, or dialect-specific syntax) may produce incomplete results. For production-grade SQL parsing, consider sqlglot.

Features

Module	Class	Purpose
data_cleaner	DataCleaner	Missing-value imputation, duplicate removal, type conversion, Excel export
anomaly_detector	AnomalyDetector	Outlier detection via IQR and Z-score
report_generator	ReportGenerator	Plain-text and Markdown data summaries
query_optimizer	QueryOptimizer	Static SQL analysis and optimization hints

Requirements

• Python 3.10+
• pandas >= 2.0
• numpy >= 1.24
• openpyxl >= 3.1 (Excel I/O support)
• pytest >= 7.4 (testing)
• tabulate >= 0.9.0 (Markdown reports)

Installation

git clone https://github.com/JCbral04/python-data-toolkit
cd python-data-toolkit
pip install -r requirements.txt

Or install in editable mode:

pip install -e .

Quick Start

import pandas as pd
from pdt import DataCleaner, AnomalyDetector, ReportGenerator, QueryOptimizer

# Load data
df = pd.read_csv("data.csv")

# Clean step by step
cleaner = DataCleaner(df)
cleaner.handle_missing_values(strategy="median")
cleaner.remove_duplicates(keep="first")
cleaner.convert_types({"date": "datetime64[ns]", "amount": "float64"})
cleaner.to_excel("output/cleaned_data.xlsx")
cleaned_df = cleaner.data

# Detect anomalies
detector = AnomalyDetector(cleaned_df)
flags = detector.detect(method="both")
anomalies = detector.get_anomaly_rows()

# Generate report
report = ReportGenerator(cleaned_df)
text_report = report.generate(format="text")
report.save("reports/q1_summary.md", format="markdown")

# Analyze SQL
optimizer = QueryOptimizer()
analysis = optimizer.analyze("SELECT * FROM users WHERE age > 18")
report = optimizer.generate_report(analysis, format="text")
print(report)

# Compare two queries
comparison = optimizer.compare_queries(
    "SELECT * FROM orders",
    "SELECT id FROM orders WHERE status = 'completed'"
)

API Reference

DataCleaner

Handles tabular data preparation.

cleaner = DataCleaner(df)

# Missing values: mean | median | mode | zero | drop
cleaner.handle_missing_values(strategy="median", columns=["revenue"])

# Duplicates: keep first | last | none
cleaner.remove_duplicates(subset=["email"], keep="first")

# Type conversion
cleaner.convert_types({"price": "float64", "created_at": "datetime64[ns]"})

# Export to Excel
cleaner.to_excel("output/data.xlsx", sheet_name="Cleaned")

# Diagnostics
summary = cleaner.get_missing_summary()

Raises: DataCleanerError on invalid input, empty DataFrames, or incompatible strategies.

AnomalyDetector

Flags outliers using statistical fences.

detector = AnomalyDetector(df)

# method: iqr | zscore | both
flags = detector.detect(columns=["amount"], method="both")
rows = detector.get_anomaly_rows()
summary = detector.get_summary()

Raises: AnomalyDetectorError when no numeric columns exist or parameters are invalid.

ReportGenerator

Produces structured summaries for stakeholders and logs.

generator = ReportGenerator(df)

text_report = generator.generate(format="text")
md_report = generator.generate(
    format="markdown",
    include_stats=True,
    include_missing=True,
    sample_rows=10,
)
generator.save("output/report.md", format="markdown")

Raises: ReportGeneratorError on empty data or I/O failures.

QueryOptimizer

Static SQL linting without a database connection.

optimizer = QueryOptimizer()

analysis = optimizer.analyze("SELECT * FROM users")
report = optimizer.generate_report(analysis, format="text")

comparison = optimizer.compare_queries(query_a, query_b)

Returns a QueryAnalysis dataclass with tables, columns, feature flags, warnings, suggestions, and an estimated complexity rating.

Raises: QueryOptimizerError on empty or invalid query strings.

Project Structure

python-data-toolkit/
├── README.md
├── LICENSE
├── pyproject.toml
├── requirements.txt
├── .gitignore
├── src/
│   └── pdt/
│       ├── __init__.py
│       ├── _logging.py
│       ├── cli.py
│       ├── data_cleaner.py
│       ├── anomaly_detector.py
│       ├── report_generator.py
│       └── query_optimizer.py
├── examples/
│   ├── tutorial.ipynb
│   ├── 01_data_cleaning.py
│   ├── 02_anomaly_detection.py
│   ├── 03_report_generation.py
│   └── 04_sql_analysis.py
└── tests/
    ├── conftest.py
    ├── test_data_cleaner.py
    ├── test_anomaly_detector.py
    ├── test_report_generator.py
    └── test_query_optimizer.py

Error Handling

All modules define domain-specific exceptions:

• DataCleanerError
• AnomalyDetectorError
• ReportGeneratorError
• QueryOptimizerError

Input validation runs at construction time and before each operation. Methods return copies of internal state via .data properties to prevent unintended mutation.

Testing

pytest tests/ -v

Current Coverage

Module	Tests	Status
DataCleaner	19	✓ Complete
AnomalyDetector	7	✓ Complete
ReportGenerator	5	✓ Complete
QueryOptimizer	6	✓ Complete
Total	37	✓ All passing

Code coverage: 68% (measured by Codecov)

Tested Scenarios

DataCleaner:

• handle_missing_values: mean, median, mode, zero, drop strategies
• Error handling: invalid strategy, non-numeric mean/median
• remove_duplicates: first, last, none
• convert_types: int64, datetime64
• get_missing_summary: with and without missing values
• to_excel: Excel export with valid file output

AnomalyDetector:

• detect: IQR, Z-score, both (combined)
• get_anomaly_rows: filtering anomalous rows
• get_summary: statistical summary
• Error handling: invalid method, no numeric columns

ReportGenerator:

• generate: text and markdown formats
• save: file persistence
• generate: custom extra sections
• Error handling: invalid format

QueryOptimizer:

• analyze: basic SELECT, SELECT * detection, empty query
• generate_report: text format
• Error handling: empty query, non-string input, invalid format

Examples

Runnable scripts demonstrating each module of the toolkit.

Quick Start

# All examples assume you're in the project root
cd python-data-toolkit

# 1. Data cleaning
python examples/01_data_cleaning.py

# 2. Anomaly detection
python examples/02_anomaly_detection.py

# 3. Report generation
python examples/03_report_generation.py

# 4. SQL analysis
python examples/04_sql_analysis.py

CLI

Use the toolkit directly from your terminal after installation:

pip install -e .

# Clean a dataset
pdt clean data.csv --strategy median --output cleaned.csv

# Detect anomalies
pdt detect data.csv --method both --output anomalies.csv

# Generate a report
pdt report data.csv --format markdown --output report.md

# Analyze a SQL query
pdt analyze "SELECT * FROM users WHERE age > 18"

Design Principles

• Immutable outputs: Public methods return copies; internal state is updated only through explicit method calls.
• Type hints: Full annotations for IDE support and static analysis.
• Docstrings: NumPy-style documentation on all public classes and methods.
• Fail fast: Clear error messages with actionable context.
• Test-driven: 37 unit tests covering all modules and edge cases.
• CI/CD: GitHub Actions runs the full test suite on every push.

Author

Juan Esteban Cabral Bautista
Python Data Toolkit Team

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Version: 1.0.0
License: MIT