def _reduceSelf(self):
"""
Parse our unit and reduce ourselves to the smallest representation
"""
if isinstance(self.unit, basestring):
self.unit = self.__findUnit()
a = self.amount * self.prefix
self.amount, self.prefix = Prefix.closestPrefix(a)
def __findUnit(self):
"""
Take a string like kV and work out prefix and units, obviously
there is scope for collision between units and prefixes...
:return: :mod:`Unit` object
"""
if not self.unit:
return NO_UNIT
if isinstance(self.unit, Unit.Unit):
return self.unit
u = self.unit
if Unit.hasUnit(u):
return Unit.getUnit(u)
# Work backwards through the list trying to find a unit that matches
unit = self.unit = None
ul = list(u)
u = ""
while ul:
u = (ul.pop() + u)
if Unit.hasUnit(u):
unit = Unit.getUnit(u)
break
# Nothing left to look at
if not ul:
if not unit:
# Make a temporary unit, since we don't know what this is
unit = Unit.Unit(u, u, True)
return unit
# We have left overs... this should be a prefix...
ul = ''.join(ul)
if Prefix.hasPrefix(ul):
self.amount *= Prefix.getPrefix(ul)
return unit
def to(self, prefix):
u"""
Convert to different prefix (i.e. seconds to ms) with no units e.g.
>>> q = Quantity(1, 'km')
>>> q
1.0 km
>>> q.to('m')
1000.0
>>> q.to('mm')
1000000.0
>>> q.to('Mm')
0.001
:param prefix: A prefix / unit to convert to
:return: A floating point scalar or None for invalid prefix
"""
if prefix.endswith(self.unit.unit):
prefix = prefix[:-len(self.unit.unit)]
if Prefix.hasPrefix(prefix):
return int(self) / Prefix.getPrefix(prefix)
return None
def testSimplePrefix(self):
r = Prefix.closestPrefix(1000)
assert r == (1.0, Prefix.Prefixes.kilo)
def testSmallPrefix(self):
r = Prefix.closestPrefix(0.05)
assert r == (50, Prefix.Prefixes.milli)
def testNegativePrefix(self):
r = Prefix.closestPrefix(-1000)
assert r == (-1.0, Prefix.Prefixes.kilo), r
def testComplexPrefix(self):
r = Prefix.closestPrefix(1024)
assert r == (1.024, Prefix.Prefixes.kilo)
