larzunits

Unit conversion with dimensional checking. Pure Python, zero dependencies.

Convert between units and refuse nonsense: metres to feet is fine, metres to kilograms raises. Handles the affine temperature scales (C/F/K) correctly, and a Quantity type carries a value-with-unit so you can add and compare safely.

from larzunits import convert, Quantity

convert(5, "km", "mi")                 # 3.106...
convert(100, "C", "F")                 # 212.0
convert(1, "KiB", "byte")              # 1024.0

Quantity(5, "m") + Quantity(30, "cm")  # 5.3 m
Quantity(1, "km") > Quantity(500, "m") # True
Quantity(60, "mi") + Quantity(1, "kg") # raises IncompatibleUnits

Why

• Catches mistakes. Converting or adding across dimensions raises IncompatibleUnits instead of silently returning garbage.
• Temperature done right. C/F/K are affine (offsets, not just factors) — 0 °C = 32 °F = 273.15 K — and larzunits handles that, where a naive factor table gets it wrong.
• Batteries of units. Length, mass, time, temperature, data (decimal kb and binary KiB), and volume — imperial and metric.
• A real Quantity type. to(), +/- (dimension-checked), scalar *//, quantity/quantity ratio, equality and ordering by underlying value.
• Zero dependencies. No pint, no quantities.

Install

pip install larzunits

Usage

from larzunits import convert, Quantity, compatible, dimension

convert(12, "in", "ft")           # 1.0
compatible("m", "ft")             # True
dimension("mph") if False else dimension("m")   # 'length'

q = Quantity(90, "min")
q.to("h").value                   # 1.5
(Quantity(1, "km") / Quantity(250, "m"))   # 4.0  (dimensionless)

Units: length (m km cm mm um nm mi yd ft in nmi), mass (kg g mg t lb oz st), time (s ms min h day week), temperature (K C F), data (bit byte kb mb gb tb KiB MiB GiB TiB), volume (l ml cl gal pt cup).

Tests

python -m unittest discover -s tests -v   # 21 tests incl. temperature + errors

The Larz stack

One of 30+ pure-Python, zero-dependency libraries at github.com/larz-scripter.

License

MIT © larz-scripter