def reduce_unit(self, guide_unit=None):
"""
Combine similar component units and scale, to form an
equal Quantity in simpler units.
Returns underlying value type if unit is dimensionless.
"""
key = (self.unit, guide_unit)
if key in Quantity._reduce_cache:
(unit, value_factor) = Quantity._reduce_cache[key]
else:
value_factor = 1.0
canonical_units = {
} # dict of dimensionTuple: (Base/ScaledUnit, exponent)
# Bias result toward guide units
if guide_unit is not None:
for u, exponent in guide_unit.iter_base_or_scaled_units():
d = u.get_dimension_tuple()
if d not in canonical_units:
canonical_units[d] = [u, 0]
for u, exponent in self.unit.iter_base_or_scaled_units():
d = u.get_dimension_tuple()
# Take first unit found in a dimension as canonical
if d not in canonical_units:
canonical_units[d] = [u, exponent]
else:
value_factor *= (u.conversion_factor_to(
canonical_units[d][0])**exponent)
canonical_units[d][1] += exponent
new_base_units = {}
for d in canonical_units:
u, exponent = canonical_units[d]
if exponent != 0:
assert u not in new_base_units
new_base_units[u] = exponent
# Create new unit
if len(new_base_units) == 0:
unit = dimensionless
else:
unit = Unit(new_base_units)
# There might be a factor due to unit conversion, even though unit is dimensionless
# e.g. suppose unit is meter/centimeter
if unit.is_dimensionless():
unit_factor = unit.conversion_factor_to(dimensionless)
if unit_factor != 1.0:
value_factor *= unit_factor
# print "value_factor = %s" % value_factor
unit = dimensionless
Quantity._reduce_cache[key] = (unit, value_factor)
# Create Quantity, then scale (in case value is a container)
# That's why we don't just scale the value.
result = Quantity(self._value, unit)
if value_factor != 1.0:
# __mul__ strips off dimensionless, if appropriate
result = result * value_factor
if unit.is_dimensionless():
assert unit is dimensionless # should have been set earlier in this method
if is_quantity(result):
result = result._value
return result
def reduce_unit(self, guide_unit=None):
"""
Combine similar component units and scale, to form an
equal Quantity in simpler units.
Returns underlying value type if unit is dimensionless.
"""
key = (self.unit, guide_unit)
if key in Quantity._reduce_cache:
(unit, value_factor) = Quantity._reduce_cache[key]
else:
value_factor = 1.0
canonical_units = {} # dict of dimensionTuple: (Base/ScaledUnit, exponent)
# Bias result toward guide units
if guide_unit is not None:
for u, exponent in guide_unit.iter_base_or_scaled_units():
d = u.get_dimension_tuple()
if d not in canonical_units:
canonical_units[d] = [u, 0]
for u, exponent in self.unit.iter_base_or_scaled_units():
d = u.get_dimension_tuple()
# Take first unit found in a dimension as canonical
if d not in canonical_units:
canonical_units[d] = [u, exponent]
else:
value_factor *= (u.conversion_factor_to(canonical_units[d][0])**exponent)
canonical_units[d][1] += exponent
new_base_units = {}
for d in canonical_units:
u, exponent = canonical_units[d]
if exponent != 0:
assert u not in new_base_units
new_base_units[u] = exponent
# Create new unit
if len(new_base_units) == 0:
unit = dimensionless
else:
unit = Unit(new_base_units)
# There might be a factor due to unit conversion, even though unit is dimensionless
# e.g. suppose unit is meter/centimeter
if unit.is_dimensionless():
unit_factor = unit.conversion_factor_to(dimensionless)
if unit_factor != 1.0:
value_factor *= unit_factor
# print "value_factor = %s" % value_factor
unit = dimensionless
Quantity._reduce_cache[key] = (unit, value_factor)
# Create Quantity, then scale (in case value is a container)
# That's why we don't just scale the value.
result = Quantity(self._value, unit)
if value_factor != 1.0:
# __mul__ strips off dimensionless, if appropriate
result = result * value_factor
if unit.is_dimensionless():
assert unit is dimensionless # should have been set earlier in this method
if is_quantity(result):
result = result._value
return result
