def test_cgs_equivalent():
"""
Get cgs equivalent to some unit.
"""
from dimensionful.dimensions import mass_density
from dimensionful.units import get_conversion_factor
Msun_cgs = 1.98892e33
Mpc_cgs = 3.08568e24
u1 = Unit("Msun * Mpc**-3")
u2 = Unit("g * cm**-3")
u3 = u1.get_cgs_equivalent()
assert u2.expr == u3.expr
assert u2 == u3
assert equal_sigfigs(u1.cgs_value, Msun_cgs / Mpc_cgs ** 3, 8)
assert u2.cgs_value == 1
assert u3.cgs_value == 1
assert u1.dimensions == mass_density
assert u2.dimensions == mass_density
assert u3.dimensions == mass_density
assert equal_sigfigs(get_conversion_factor(u1, u3), Msun_cgs / Mpc_cgs ** 3, 8)
def convert_to(self, units):
"""
Convert the data and units to given unit. This overwrites the ``data``
and ``units`` attributes, making no copies, and returns None.
Parameters
----------
units : Unit object or string
The units you want the data in.
"""
new_units = self._unit_repr_check_same(units)
conversion_factor = get_conversion_factor(self.units, new_units)
self.data *= conversion_factor
self.units = new_units
return self
def get_in(self, units):
"""
Creates a new Quantity with the data in the supplied units, and returns
it. Does not modify this object.
Parameters
----------
units : Unit object or string
The units you want to get a new quantity in.
Returns
-------
Quantity object with converted data and supplied units.
"""
new_units = self._unit_repr_check_same(units)
conversion_factor = get_conversion_factor(self.units, new_units)
return Quantity(self.data * conversion_factor, new_units)
def get_data_in(self, units):
"""
Returns the data, converted to the supplied units.
Parameters
----------
units : Unit object or string
The units you want the data in.
Returns
-------
``data`` attribute, multiplied by the conversion factor to the supplied
units.
"""
new_units = self._unit_repr_check_same(units)
# don't operate on data if given the same units
if self.units == new_units:
return self.data
conversion_factor = get_conversion_factor(self.units, new_units)
return self.data * conversion_factor
