polars-tsfresh 0.1.1

Fast implementation of tsfresh time series feature extraction using Polars

polars-tsfresh

A high-performance Polars-based reimplementation of tsfresh for time series feature extraction.

polars-tsfresh extracts statistical features from time series data stored in Polars DataFrames. It's designed as a faster, more type-safe alternative to tsfresh, leveraging Polars' efficient columnar operations for better performance on grouped time series data.

Installation

With uv (Recommended)

uv add polars-tsfresh

With pip

pip install polars-tsfresh

Requirements

• Python 3.12+
• Polars >= 1.36.1

Quick Start

import polars as pl
from polars_tsfresh import extract_features

# Load your time series data
df = pl.read_csv("data.csv")
print(df.head())
# shape: (5, 5)
# ┌────────────┬─────────┬─────────┬─────────┬─────────┐
# │ date       ┆ open    ┆ high    ┆ low     ┆ close   │
# │ ---        ┆ ---     ┆ ---     ┆ ---     ┆ ---     │
# │ str        ┆ f64     ┆ f64     ┆ f64     ┆ f64     │
# ╞════════════╪═════════╪═════════╪═════════╪═════════╡
# │ 2025/12/03 ┆ 6815.29 ┆ 6862.42 ┆ 6810.43 ┆ 6849.72 │
# │ 2025/12/04 ┆ 6866.47 ┆ 6866.47 ┆ 6827.12 ┆ 6857.12 │
# │ 2025/12/05 ┆ 6866.32 ┆ 6895.78 ┆ 6858.29 ┆ 6870.40 │
# │ ...        ┆ ...     ┆ ...     ┆ ...     ┆ ...     │
# └────────────┴─────────┴─────────┴─────────┴─────────┘

Add an ID column to group by (here we're treating all data as one time series):

df = df.with_columns(pl.lit("sp500").alias("kind"))

Extract features:

features = extract_features(df, column_id="kind", column_sort="date")
print(features)
# shape: (1, 11)
# ┌────────────┬────────────┬────────────┬────────────┬────────────┬────────────┬────────────┬────────────┬────────────┬────────────┬────────────┐
# │ kind       ┆ close__sum ┆ close__med ┆ close__mea ┆ close__len ┆ close__std ┆ close__var ┆ close__rms ┆ close__max ┆ close__abs ┆ close__min │
# │ ---        ┆ _values    ┆ ian        ┆ n          ┆ gth        ┆            ┆            ┆            ┆            ┆ _maximum   ┆            │
# │ str        ┆ ---        ┆ ---        ┆ ---        ┆ ---        ┆ ---        ┆ ---        ┆ ---        ┆ ---        ┆ ---        ┆ ---        │
# │ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        ┆ f64        │
# ╞════════════╪════════════╪════════════╪════════════╪════════════╪════════════╪════════════╪════════════╪════════════╪════════════╪════════════╡
# │ sp500      ┆ 137124.56  ┆ 6853.42    ┆ 6856.228   ┆ 20.0       ┆ 51.503     ┆ 2652.59    ┆ 6856.421   ┆ 6932.05    ┆ 6932.05    ┆ 6721.43    │
# └────────────┴────────────┴────────────┴────────────┴────────────┴────────────┴────────────┴────────────┴────────────┴────────────┴────────────┘

The output shows features extracted for each group (in this case, one group "sp500") with features named using the column__feature convention from tsfresh.

Features

Current Minimal Feature Set

polars-tsfresh currently implements the "minimal" feature set from tsfresh, providing essential statistical measures:

Feature	Description	tsfresh Equivalent
mean	Arithmetic mean of values	tsfresh.feature_extraction.mean
median	Median value	tsfresh.feature_extraction.median
variance	Variance (ddof=0)	tsfresh.feature_extraction.variance
standard_deviation	Standard deviation (ddof=0)	tsfresh.feature_extraction.standard_deviation
length	Number of data points	tsfresh.feature_extraction.length
maximum	Maximum value	tsfresh.feature_extraction.maximum
minimum	Minimum value	tsfresh.feature_extraction.minimum
absolute_maximum	Maximum absolute value	tsfresh.feature_extraction.absolute_maximum
root_mean_square	Root mean square (RMS)	tsfresh.feature_extraction.root_mean_square
sum_values	Sum of all values	tsfresh.feature_extraction.sum_values

Performance Benefits

• Polars Expressions: Uses Polars' vectorized operations for optimal performance
• Grouped Operations: Efficiently handles multiple time series in a single DataFrame
• Type Safety: Full type hints and static analysis support
• Memory Efficient: Columnar operations reduce memory overhead

Roadmap

The project plans to implement comprehensive feature sets including:

• Distribution Features: skewness, kurtosis, quantiles, entropy
• Change & Rate Features: derivatives, trend analysis
• Position & Extrema Features: peak detection, location analysis
• Frequency Features: FFT coefficients, spectral analysis
• Autocorrelation Features: time series modeling
• Complexity Features: entropy measures, complexity estimates

See plan/tsfresh.yaml for the complete feature roadmap.

API Reference

extract_features(df, column_id, column_sort)

Extract features from a time series DataFrame.

Parameters:

• df (pl.DataFrame): Input DataFrame containing time series data
• column_id (str): Name of the column containing group IDs
• column_sort (str): Name of the column to sort by (typically time/date)

Returns:

• pl.DataFrame: DataFrame with extracted features, one row per group

Example:

features = extract_features(
    df=my_dataframe,
    column_id="stock_symbol",
    column_sort="timestamp"
)

Development

Setup

# Clone the repository
git clone https://github.com/lucidfrontier45/polars-tsfresh.git
cd polars-tsfresh

# Install with uv (includes dev dependencies)
uv sync

Testing

# Run all tests
uv run poe test

# Run specific test
uv run pytest tests/data/test_minimal.py::test_minimal

# Run with coverage
uv run pytest tests/ --cov=polars_tsfresh --cov-report=html

Code Quality

# Full quality check (linting + type checking)
uv run poe check

# Format code
uv run poe format

# Individual checks
uv run poe ruff_check    # Linting
uv run poe pyrefly_check # Type checking

Project Structure

polars-tsfresh/
├── src/polars_tsfresh/
│   ├── __init__.py      # Main API
│   └── features.py      # Feature implementations
├── tests/
│   └── data/
│       ├── test_minimal.py    # Test suite
│       ├── sp500_raw.csv      # Test data
│       └── sp500_tsfresh_features.csv  # Expected results
├── plan/
│   ├── tsfresh.yaml     # Feature definitions
│   └── dev_plan.md      # Development roadmap
└── pyproject.toml       # Project configuration

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Add tests for new functionality
4. Ensure all checks pass: uv run poe check && uv run poe test
5. Submit a pull request

See AGENTS.md for detailed development guidelines and coding standards.

Related Projects

• tsfresh: The original Python package for time series feature extraction
• Polars: Fast DataFrame library powering this implementation

License

Licensed under the Apache License 2.0. See LICENSE for details.

Authors

• 杜世橋 Du Shiqiao - Initial work - [e-mail]