eulumdat-analysis 1.0.0

Practical photometric calculations on EULUMDAT data

eulumdat-analysis

Practical photometric calculations on EULUMDAT data.

Part of the eulumdat-* Python ecosystem built on eulumdat-py.
Developed in an ISO 17025 accredited photometry laboratory.

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Features

• half_angle — half-angle at half maximum (HAHM) per C-plane, with CubicSpline interpolation
• Handles all ISYM symmetry types including full rotational symmetry (ISYM=1)
• Automatically rejects multi-peak distributions (secondary peak prominence > 5 % of I_max)
• Returns None for undefined cases — never raises unhandled exceptions

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Installation

pip install eulumdat-analysis

For development:

git clone https://github.com/123VincentB/eulumdat-analysis.git
cd eulumdat-analysis
pip install -e ".[dev]"

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Quick start

from pyldt import LdtReader
from ldt_analysis import half_angle

ldt = LdtReader.read("luminaire.ldt")

result = half_angle(ldt, [0.0, 90.0, 180.0, 270.0])
print(result)
# {0.0: 35.4, 90.0: 36.1, 180.0: 35.8, 270.0: 36.0}

The function returns the absolute gamma angle (degrees from nadir) where intensity drops to 50 % of the C-plane maximum, searching from γ_max toward 90°.

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Examples

File	Description
examples/01_basic_usage.md	Basic usage, return values, FWHM

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Project structure

eulumdat-analysis/
├── src/
│   └── ldt_analysis/
│       ├── __init__.py
│       └── half_angle.py
├── examples/
│   └── 01_basic_usage.md
├── tests/
│   └── test_half_angle.py
├── CHANGELOG.md
├── LICENSE
└── README.md

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Dependencies

• eulumdat-py ≥ 1.0.0 — EULUMDAT parser
• scipy ≥ 1.7 — CubicSpline interpolation and Brent root-finding

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half_angle — return values

Case	Return value
Normal beam	float — crossing angle in degrees
C-plane not found in file (±0.01°)	None
I_max = 0 (dark or inactive plane)	None
Intensity never drops to half-max within [γ_max, 90°]	None
Multi-peak distribution	None

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License

MIT — see LICENSE.

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Context

This package was developed as a practical tool in the context of ISO 17025 accredited photometric testing. It is shared as open-source in the hope that it will be useful to others working with EULUMDAT files in Python.