firkin

Firkin, a Python module designed to convert between different measurement units, is a handy tool for anyone who deals with unit conversions on a regular basis.

To start using Firkin, you'll first need to create an instance of UnitManager using the following command:

>>> um=UnitManager()

Next, you can create two families of units. The first is liter, which uses SIFamily to automatically create units with the SI prefixes. Here's a list of the prefixes and their meanings:

prefix meaning value
f femto 10-15
p pico 10-12
n nano 10-9
µ micro 10-6
m milli 10-3
k kilo 103
M mega 106
G giga 109
T tera 1012

To add the liter family to your UnitManager instance, use the following command:

>>> um.add(SIFamily(base='l', name='liter'))

Now you have a UnitManager instance that knows about fl, pl, nl, ..., Ml, Gl, and Tl. To convert 10000 ml to liters, simply use the convert_to_unit method:

>>> um.convert_to_unit(1e4, 'ml', 'l')
(Decimal("10.0000"), 'l')

Next, you can create a family by hand using the Family class. Here's an example:

>>> f=Family(name='f', base='gallon')
>>> f.add('barrel', 36, 'gallon')
>>> f.add('kilderkin', 0.5, 'barrel')
>>> f.add('firkin', 0.5, 'kilderkin')

Now you have a family called f that uses gallon as its base and knows about barrel, kilderkin, and firkin. To convert one firkin to gallons, use the following command:

>>> f.convert(1, 'firkin', 'gallon')
(Decimal("9.00"), 'gallon')

And to find the best way to express 3 kilderkin, use the autoconvert method:

>>> f.autoconvert(3, 'kilderkin')
(Decimal("1.50"), 'barrel')

To convert between family f and family liter, you'll need to add f to your UnitManager instance and tell Firkin how much liters (the base unit of family liter) a gallon (the base unit of family f) is. Here's an example:

>>> um.add(f, other='liter', factor=4.54609)

Now you can convert between firkin and gallon:

>>> um.convert_to_unit(1, 'firkin', 'gallon')
(Decimal("9.00"), 'gallon')

Or between firkin and liters:

>>> um.convert_to_unit(1, 'firkin', 'l')
(Decimal("40.9148100"), 'l')

You can even find the best way to express one liter in one of the units from family f:

>>> um.convert_to_family(1, 'l', 'f')
(Decimal("0.219969248299"), 'gallon')

This works with barrels