Module firkin :: Class UnitManager

Class UnitManager

object --+
         |
        UnitManager

A UnitManager hold a collection of Family objects and allows to convert between their units.

>>> um=UnitManager()
>>> um.add(SIFamily(base='l', name='liter'))
>>>
>>> f=Family(name='f', base='gallon')
>>> f.add('barrel', 36, 'gallon')
>>> f.add('kilderkin', 0.5, 'barrel')
>>> f.add('firkin', 0.5, 'kilderkin')
>>> um.add(f, other='liter',  factor=4.54609)
>>>
>>> um.add(Family(base='°C'))
>>> um.add(Family(base='°F'), other='°C', offset=(-32/1.8), factor=5.0/9) 
>>> um.convert_to_unit(1e4, 'ml', 'l')
(Decimal("10.0000"), 'l')
>>> um.convert_to_unit(1, 'firkin', 'gallon')
(Decimal("9.00"), 'gallon')
>>> um.convert_to_family(1, 'firkin', 'liter')
(Decimal("40.9148100"), 'l')
>>> um.convert_to_family(1, 'l', 'f')
(Decimal("0.219969248299"), 'gallon')
>>> um.convert_to_family(1, 'barrel', 'f')
(Decimal("1.00"), 'barrel')
>>> um.convert_to_unit(32, '°F', '°C')
(Decimal("-8E-12"), '\xc2\xb0C')
>>> um.convert_to_unit(100, '°C', '°F')
(Decimal("212.0"), '\xc2\xb0F')
>>> um.convert_to_unit(1, '°C', 'ml')
(None, None)

Instance Methods

[hide private]

__init__(self)
Constructor

source code

add(self, family, other=None, factor=1, offset=0, groups=None)
Add another Family object.

source code

shortest_path(self, start, end, path=None)
Finds the shortest conversion path between start and end.

source code

convert_to_family(self, amount, unit, family)
Convert amount of unit to the unit in family that fits best.

source code

convert_to_unit(self, amount, unit, dest)
Convert amount of unit to unit dest.

source code

convert_to_group(self, amount, unit, group)
Convert amount of unit to the unit in group that fits best.

source code

Inherited from object: __delattr__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __str__

Properties

[hide private]

Inherited from object: __class__

Method Details

[hide private]

init(self)
(Constructor)

source code

Constructor

Overrides: object.__init__

add(self, family, other=None, factor=1, offset=0, groups=None)

source code

Add another Family object.

If other is not None a conversion path

family = other * factor + offset

and its reverse path are added.

Raises:

KeyError - if other is a string and there's no known unit with this name
TypeError - if factor or offset has a wrong type
AttributeError - if family has a wrong type

shortest_path(self, start, end, path=None)

source code

Finds the shortest conversion path between start and end.

Parameters:

start (name of a Family that has been added by add) - family to start with
end (name of a Family that has been added by add) - family to end with

Returns: