traj-dist-rs 1.0.0rc2

High-performance trajectory distance & similarity measures in Rust with Python bindings

traj-dist-rs

High-performance trajectory distance & similarity measures in Rust and Python.

A high-performance Rust implementation of trajectory distance algorithms with Python bindings, offering significant speed improvements over the original traj-dist library.

About

traj-dist-rs is a high-performance trajectory distance calculation library written in Rust, providing both native Rust APIs and Python bindings via PyO3. It is a complete rewrite of the original traj-dist library, focusing on performance optimization and modern language features.

Why traj-dist-rs?

• Performance: ~82x faster than Python implementation and ~3x faster than Cython implementation on average
• Batch Computation: Native pdist and cdist functions with parallel support up to 130x faster than traj-dist
• Zero Dependencies: Only requires numpy >= 1.21 - no heavy dependencies like polars, pyarrow, pandas, or shapely
• Safety: Rust's memory safety guarantees eliminate common runtime errors
• Cross-platform: Supports Linux, macOS, and Windows with native binaries
• Dual API: Use it from Python or Rust with minimal overhead
• Accuracy: All algorithms verified against original implementation with < 1e-8 error margin

Features

Supported Distance Algorithms

Algorithm	Full Name	Best For
SSPD	Symmetric Segment-Path Distance	General similarity, noise tolerance
DTW	Dynamic Time Warping	Similarity with time warping, flexible alignment
Discret Frechet	Discrete Fréchet Distance	Geometric similarity, path-based matching
Hausdorff	Hausdorff Distance	Maximum distance, outlier-sensitive similarity
LCSS	Longest Common Subsequence	Robust similarity with noise tolerance
EDR	Edit Distance on Real sequence	Similarity with noise and outlier tolerance
ERP	Edit distance with Real Penalty	Robust similarity with gap handling

Distance Types

• Euclidean - 2D Euclidean distance
• Spherical - Haversine distance for geographic coordinates

Batch Computation

• pdist - Pairwise distance matrix for trajectory collections (compressed format)
• cdist - Cross-distance matrix between two trajectory collections
• Parallel processing - Automatic parallelization using Rayon for large datasets
• Metric API - Type-safe configuration with factory methods

Additional Features

• Matrix return for DP-based algorithms (DTW, LCSS, EDR, ERP, Discret Frechet)
• Precomputed distance matrix support for efficient batch computations
• Zero-copy NumPy array support for optimal performance
• Pickle serialization for DpResult objects (compatible with joblib)
• Comprehensive error handling for invalid inputs
• Full Python type hints for better IDE support

Keywords / Search Terms

Common search terms related to this library:

• Core concepts: trajectory similarity, trajectory distance, similarity measures, trajectory analysis
• Algorithms: DTW, LCSS, EDR, ERP, Fréchet distance, Hausdorff distance, SSPD
• Applications: trajectory clustering, trajectory similarity search, nearest neighbor retrieval, mobility data analysis, GPS trace analysis
• Domains: time series similarity, spatiotemporal data, movement pattern mining, anomaly detection

Migration from traj-dist

If you used the original traj-dist library for trajectory similarity measurement, this library is compatible and offers significant performance improvements:

• Algorithm compatibility: Core algorithms (SSPD, DTW, Hausdorff, LCSS, EDR, ERP) supported
• Performance: 3-10x faster than Cython implementation

Quick Start

Python

import numpy as np
import traj_dist_rs

# Define trajectories as list of [x, y] coordinates or numpy arrays
traj1 = [[0.0, 0.0], [1.0, 1.0], [2.0, 2.0]]
traj2 = [[0.1, 0.1], [1.1, 1.1], [2.1, 2.1]]

# Calculate SSPD distance
distance = traj_dist_rs.sspd(traj1, traj2, dist_type="euclidean")
print(f"SSPD distance: {distance}")

# Calculate DTW distance (returns DpResult with distance and optional matrix)
result = traj_dist_rs.dtw(traj1, traj2, dist_type="euclidean", use_full_matrix=False)
print(f"DTW distance: {result.distance}")

# Calculate Hausdorff distance
distance = traj_dist_rs.hausdorff(traj1, traj2, dist_type="spherical")
print(f"Hausdorff distance: {distance}")

# Batch computation with pdist (pairwise distances)
trajectories = [np.array([[0.0, 0.0], [1.0, 1.0]]) for _ in range(10)]
metric = traj_dist_rs.Metric.sspd(type_d="euclidean")
distances = traj_dist_rs.pdist(trajectories, metric=metric, parallel=True)
print(f"Computed {len(distances)} pairwise distances")

# Cross-distance computation with cdist
dist_matrix = traj_dist_rs.cdist(trajectories[:5], trajectories[5:], metric=metric)
print(f"Distance matrix shape: {dist_matrix.shape}")

Rust

use traj_dist_rs::distance::sspd::sspd;
use traj_dist_rs::distance::dtw::dtw;
use traj_dist_rs::distance::base::TrajectoryCalculator;
use traj_dist_rs::distance::distance_type::DistanceType;
use traj_dist_rs::distance::batch::{pdist, Metric, DistanceAlgorithm};

fn main() {
    let traj1 = vec![[0.0, 0.0], [1.0, 1.0], [2.0, 2.0]];
    let traj2 = vec![[0.1, 0.1], [1.1, 1.1], [2.1, 2.1]];

    // Calculate SSPD distance
    let dist = sspd(&traj1, &traj2, DistanceType::Euclidean);
    println!("SSPD distance: {}", dist);

    // Calculate DTW distance
    let calculator = TrajectoryCalculator::new(&traj1, &traj2, DistanceType::Euclidean);
    let result = dtw(&calculator, false);
    println!("DTW distance: {}", result.distance);

    // Batch computation with pdist
    let trajectories = vec![
        vec![[0.0, 0.0], [1.0, 1.0]],
        vec![[0.0, 1.0], [1.0, 0.0]],
        vec![[0.5, 0.5], [1.5, 1.5]],
    ];
    let metric = Metric::new(DistanceAlgorithm::SSPD, DistanceType::Euclidean);
    let distances = pdist(&trajectories, &metric, true).unwrap();
    println!("Computed {} pairwise distances", distances.len());
}

Installation

From PyPI (Python)

pip install traj-dist-rs

Minimal Dependencies: traj-dist-rs only requires numpy >= 1.21 to function. This makes it extremely lightweight and easy to install compared to alternatives that depend on pandas, shapely, or other heavy libraries.

Requirements

• Python: 3.10, 3.11, 3.12, or 3.13
• NumPy: >= 1.21 (the only runtime dependency)
• Platform: Linux, macOS, or Windows

From crates.io (Python)

cargo add traj-dist-rs --features parallel

Installation Options

Basic Installation (minimal dependencies):

pip install traj-dist-rs

Installation with Test Dependencies (for development):

pip install traj-dist-rs[test]

From Source (requires Rust toolchain):

Prerequisites:

• Rust 1.85 or later
• uv

Build and install:

# Clone the repository
git clone https://github.com/Davidham3/traj-dist-rs.git
cd traj-dist-rs

# Compile and install via uv
uv pip install .

Rust-only build:

cargo build --release --features parallel

Performance

Compared to the original traj-dist implementation (based on median values from K=1000 trajectory pairs):

Overall Performance

Implementation	Average Speedup
Rust vs Python	~82x faster
Rust vs Cython	~3x faster

By Distance Type

Euclidean Distance:

• Rust vs Python: ~388x faster (range: 169x - 612x)
• Rust vs Cython: ~9.7x faster (range: 6.2x - 13.7x)

Spherical Distance:

• Rust vs Python: ~87x faster (range: 47x - 194x)
• Rust vs Cython: ~3.5x faster (range: 1.8x - 8.6x)

Batch Computation Performance

pdist (DTW, 5 trajectories, varying lengths):

Trajectory Length	Rust Seq vs traj-dist	Rust Par vs traj-dist
10 points	8.02x	0.14x (parallel overhead)
100 points	15.55x	10.52x
1000 points	15.76x	83.41x

cdist (DTW, 5×5, varying lengths):

Trajectory Length	Rust Seq vs traj-dist	Rust Par vs traj-dist
10 points	15.85x	1.00x (parallel overhead)
100 points	15.21x	15.15x
1000 points	15.20x	60.97x

Real-world Example: TrajCL Data Preprocessing

• Dataset: 7,000 trajectories (Porto dataset)
• Task: DTW distance matrix computation
• Performance: 31.8x faster than traj-dist baseline (2933s → 92s)

For detailed performance analysis with statistics, see performance.md.

Documentation

• Installation Guide: installation.md
• Python User Guide: usage_for_python.ipynb
• Rust User Guide: usage_for_rust.ipynb
• Performance Report: performance.md
• Examples: examples/ - Python and Rust example code

Testing

Run comprehensive integration tests:

bash scripts/pre_build.sh

Contributing

We welcome contributions! Please see our contributing guidelines:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes
4. Run tests and ensure they pass via bash scripts/pre_build.sh
5. Commit your changes (git commit -m 'Add amazing feature')
6. Push to the branch (git push origin feature/amazing-feature)
7. Open a Pull Request

Development Workflow

For daily development, use the pre-build script:

bash scripts/pre_build.sh

This script will:

• Format Rust and Python code
• Run linting (clippy, ruff)
• Run all tests (Rust + Python)
• Generate Python stub files
• Build Python bindings

Project Structure

traj-dist-rs/
├── src/
│   ├── distance/       # Distance algorithm implementations
│   ├── binding/        # Python bindings (PyO3)
│   └── lib.rs          # Library entry point
├── tests/              # Rust integration tests
├── py_tests/           # Python integration tests
├── python/             # Python package source
├── docs/               # Documentation
└── scripts/            # Build and utility scripts

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Original traj-dist library for algorithm reference
• PyO3 for Python bindings
• The Rust community for excellent tooling and libraries

Support

• Issues: Report bugs and request features via GitHub Issues
• Discussions: Join discussions about usage and development
• Documentation: Check the docs directory for detailed guides