pupyC3D 0.1.3

Pure Python C3D reader and writer for biomechanics and motion capture data

pupyC3D

A pure Python library for reading and writing C3D files, commonly used in biomechanics and motion capture applications.

Features

• Pure Python: No external dependencies except NumPy
• Cross-platform: Works on Windows, macOS, and Linux
• Full C3D support: Read and write C3D files with complete parameter and data access
• Multiple processor formats: Supports Intel, DEC, and MIPS processor formats
• Easy to use: Simple API for accessing 3D coordinates, parameters, and metadata

Installation

From PyPI (recommended)

pip install pupyC3D

From source

# Clone the repository
git clone https://github.com/Norton-breman/pupyC3D.git
cd pupyC3D

# Install in development mode
pip install -e .

Quick Start

Reading a C3D file

from pupyC3D import C3DFile

# Load a C3D file
c3d = C3DFile('example.c3d')

# Access header information
print(f"Number of 3D points: {c3d.point_count}")
print(f"Number of frames: {c3d.frame_count}")

# Access parameter groups
point_group = c3d.get_parameter_group('POINT')
if point_group:
    labels_param = point_group.get_parameter('LABELS')
    if labels_param:
        print(f"Point labels: {labels_param.value}")

# Access points data
points_list = c3d.get_point_names()
point_data = c3d.get_point_data(points_list[0])
# getting multiple points data
points_data = c3d.get_points_data(points_list)
# Access analog data
if c3d.analog_count > 0:
    analog_list = c3d.get_analog_names()
    analog_data = c3d.get_analog_data(analog_list[0])

Writing a C3D file

from pupyC3D import C3DFile
import numpy as np

# Create a new C3D file
c3d = C3DFile()

# Add parameter groups and parameters
point_group = c3d.add_parameter_group('POINT')
if point_group:
    labels_param = point_group.add_parameter('LABELS')
    labels_param.value = np.array(['MARKER1', 'MARKER2', 'MARKER3'])
    labels_param.data_type = -1  # String type

# Save the file
c3d.write('output.c3d', overwrite=True)

C3D File Format

C3D files contain:

• Header: Basic file information (number of points, frames, etc.)
• Parameters: Organized in groups (POINT, ANALOG, TRIAL, etc.)
• Data: 3D coordinates and analog data

API Reference

Main Classes

• C3DFile: Main class for reading/writing C3D files
• ParameterGroup: Container for related parameters
• Parameter: Individual parameter with typed data
• ProcStream: Low-level binary data processor

Key Methods

• C3DFile.read_file(): Load C3D file from disk
• C3DFile.write(): Save C3D file to disk
• C3DFile.get_parameter_group(): Access parameter groups by name or ID
• C3DFile.add_parameter_group(): Create new parameter groups

Requirements

• Python 3.6+
• NumPy

License

This project is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License. See the LICENSE for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Author

Antoine MARIN ([e-mail])

Changelog

v0.1.0

• Initial release
• Basic C3D reading and writing functionality
• Support for Intel, DEC, and MIPS processor formats
• Complete parameter and data access