astropyunits

Astropy units, provided by the astropy.units module, offer a robust framework for handling physical quantities with units in Python. The system centers on Unit objects that represent physical units and Quantity objects that couple a numerical value to a unit. A UnitRegistry manages units and conversions, with a large collection of predefined units from the SI system, astronomical units, and many common non-SI units.

Users can create units such as u.m, u.km, or Unit('m'). Quantities like 3.0 * u.km represent a value with a unit; arithmetic on quantities automatically converts to compatible units and enforces dimensional consistency.

Conversions are performed with the to method (for example, 1.0 * u.km).to(u.m) to yield 1000.0, and the system supports equivalencies for contexts such as temperature scales, spectral wavelength and frequency relationships, and other physics-related conversions.

Parsing and formatting features include converting strings like '10 m' into quantities and producing readable string representations for display. The module integrates with NumPy, so operations on array quantities broadcast and operate over underlying arrays efficiently, enabling vectorized calculations.

Astropy units are widely used in astronomical data analysis and physical modeling, and they interface with other subpackages such as constants, coordinates, and models to provide consistent and interoperable unit handling across the project.