unitmeasure: Swift units and measurement in Python

unitmeasure is a simple Python library that tries to implement the features of Swift's Units and Measurement framework.

With unitmeasure, you can label numeric quantities with physical dimensions and convert between related units.

Contributing

For anyone looking to contribute, you can look at doing any of the following:

• Submit bugs and feature requests
• Review any documentation and create pull requests for anything from typos to new content.

Installation

unitmeasure can be installed from PyPI:

pip install unitmeasure

Overview

Base available classes

The basic available classes should match the classes found in swift.

• Unit - represents a unit that has a symbol to describe it.
• Dimension - subclass of Unit and has multiple child classes defining different dimensions.
• Measurement - Immutable. wraps a number with a unit. Supports comparison operators, addition and subtraction with another measurement, and multiplication and division with a scalar value.

Supported Units

All supported units can be found in the units sub directory. Any unit class can be imported directly from unitmeasure.

Examples

for more detailed usage see unit tests.

Create a measurement

import unitmeasure

dur = unitmeasure.Measurement(value=2,
                              unit=unitmeasure.UnitDuration.minutes)
print(dur)

Convert a measurement

import unitmeasure

dur = unitmeasure.Measurement(value=2,
                              unit=unitmeasure.UnitDuration.minutes)

dur.convert(unitmeasure.UnitDuration.seconds)
print(dur)

Convert a measurement and return new object

import unitmeasure

minutes = unitmeasure.Measurement(value=2,
                             unit=unitmeasure.UnitDuration.minutes)

seconds = minutes.converted(unitmeasure.UnitDuration.seconds)
print(minutes)
print(seconds)

add measurements

import unitmeasure

minutes = unitmeasure.Measurement(value=2,
                             unit=unitmeasure.UnitDuration.minutes)

seconds = minutes.converted(unitmeasure.UnitDuration.seconds)
# adding measurements will automagically convert the measurement  into its base unit.
print(minutes + seconds)

Create a custom Unit

import unitmeasure

customLengthUnit = unitmeasure.UnitLength(symbol="FLARB", coefficient=2.0)

customLength = Measurement(value=1, unit=customLengthUnit)

meters = customLength.converted(to: unitmeasure.UnitLength.meters)

Converting to and from JSON

NOTE: JSON struct should match swift's so it should be possible to import json data to/from swift.

import unitmeasure

seconds = unitmeasure.Measurement(value=2,
                             unit=unitmeasure.UnitDuration.seconds)

with open("measurement.json", "w") as f:
    f.write(unitmeasure.to_json(seconds))

with open("measurement.json", "r") as f:
    # if a dimension is not specified you will end up with
    # a measurement that has a basic unit (only a symbol)
    loaded_measurement = unitmeasure.from_json(f.read(), dimension=unitmeasure.UnitDuration)