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from sympy.physics.units import DimensionSystem, joule, second, ampere
from sympy.core.numbers import Rational
from sympy.core.singleton import S
from sympy.physics.units.definitions import c, kg, m, s
from sympy.physics.units.definitions.dimension_definitions import length, time
from sympy.physics.units.quantities import Quantity
from sympy.physics.units.unitsystem import UnitSystem
from sympy.physics.units.util import convert_to
def test_definition():
# want to test if the system can have several units of the same dimension
dm = Quantity("dm")
base = (m, s)
# base_dim = (m.dimension, s.dimension)
ms = UnitSystem(base, (c, dm), "MS", "MS system")
ms.set_quantity_dimension(dm, length)
ms.set_quantity_scale_factor(dm, Rational(1, 10))
assert set(ms._base_units) == set(base)
assert set(ms._units) == {m, s, c, dm}
# assert ms._units == DimensionSystem._sort_dims(base + (velocity,))
assert ms.name == "MS"
assert ms.descr == "MS system"
def test_str_repr():
assert str(UnitSystem((m, s), name="MS")) == "MS"
assert str(UnitSystem((m, s))) == "UnitSystem((meter, second))"
assert repr(UnitSystem((m, s))) == "<UnitSystem: (%s, %s)>" % (m, s)
def test_convert_to():
A = Quantity("A")
A.set_global_relative_scale_factor(S.One, ampere)
Js = Quantity("Js")
Js.set_global_relative_scale_factor(S.One, joule*second)
mksa = UnitSystem((m, kg, s, A), (Js,))
assert convert_to(Js, mksa._base_units) == m**2*kg*s**-1/1000
def test_extend():
ms = UnitSystem((m, s), (c,))
Js = Quantity("Js")
Js.set_global_relative_scale_factor(1, joule*second)
mks = ms.extend((kg,), (Js,))
res = UnitSystem((m, s, kg), (c, Js))
assert set(mks._base_units) == set(res._base_units)
assert set(mks._units) == set(res._units)
def test_dim():
dimsys = UnitSystem((m, kg, s), (c,))
assert dimsys.dim == 3
def test_is_consistent():
dimension_system = DimensionSystem([length, time])
us = UnitSystem([m, s], dimension_system=dimension_system)
assert us.is_consistent == True
def test_get_units_non_prefixed():
from sympy.physics.units import volt, ohm
unit_system = UnitSystem.get_unit_system("SI")
units = unit_system.get_units_non_prefixed()
for prefix in ["giga", "tera", "peta", "exa", "zetta", "yotta", "kilo", "hecto", "deca", "deci", "centi", "milli", "micro", "nano", "pico", "femto", "atto", "zepto", "yocto"]:
for unit in units:
assert isinstance(unit, Quantity), f"{unit} must be a Quantity, not {type(unit)}"
assert not unit.is_prefixed, f"{unit} is marked as prefixed"
assert not unit.is_physical_constant, f"{unit} is marked as physics constant"
assert not unit.name.name.startswith(prefix), f"Unit {unit.name} has prefix {prefix}"
assert volt in units
assert ohm in units
def test_derived_units_must_exist_in_unit_system():
for unit_system in UnitSystem._unit_systems.values():
for preferred_unit in unit_system.derived_units.values():
units = preferred_unit.atoms(Quantity)
for unit in units:
assert unit in unit_system._units, f"Unit {unit} is not in unit system {unit_system}"
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