eulumdat-analysis 1.1.0

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
• resample — resample a Ldt to a coarser angular resolution (linear interpolation, ISO 17025 traceable)
• 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, resample

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

# Half-angle at half maximum per C-plane
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}

# Resample a raw 2.5°×1° measurement to standard 15°×5°
ldt_raw = LdtReader.read("luminaire_raw.ldt")   # 144 C-planes × 181 γ-angles
ldt_15x5 = resample(ldt_raw)                    # → 24 C-planes × 37 γ-angles

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Examples

File	Description
examples/01_basic_usage.md	half_angle — basic usage, return values, FWHM
examples/02_resample.md	resample — resolution resampling, guards, preserved fields

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Project structure

eulumdat-analysis/
├── src/
│   └── ldt_analysis/
│       ├── __init__.py
│       ├── half_angle.py
│       └── resample.py
├── examples/
│   ├── 01_basic_usage.md
│   └── 02_resample.md
├── tests/
│   ├── test_half_angle.py
│   └── test_resample.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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resample — return values

Case	Return value
Success	Ldt — new object at target resolution
c_step <= 0 or g_step <= 0	None
Source has fewer than 2 C-planes or γ-angles	None
Target finer than source	None

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eulumdat-* ecosystem

New to the ecosystem? eulumdat-quickstart — a step-by-step guide covering all 8 packages with working examples.

Package	Description
eulumdat-py	Read / write EULUMDAT files
eulumdat-symmetry	Symmetrise and detect ISYM
eulumdat-plot	Polar intensity diagram (SVG/PNG)
eulumdat-luminance	Luminance table and polar diagram
eulumdat-ugr	UGR catalogue (CIE 117/190)
eulumdat-analysis	Beam half-angle, FWHM — this package
eulumdat-report	Full photometric datasheet (HTML/PDF)
eulumdat-ies	LDT ↔ IES LM-63-2002 conversion

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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.