Python astropy.units.kg() Examples

def test_nested():

    with quantity_support():

        with quantity_support():

            fig = plt.figure()
            ax = fig.add_subplot(1, 1, 1)
            ax.scatter(Angle([1, 2, 3], u.deg), [3, 4, 5] * u.kg)

            assert ax.xaxis.get_units() == u.deg
            assert ax.yaxis.get_units() == u.kg

        fig = plt.figure()
        ax = fig.add_subplot(1, 1, 1)
        ax.scatter(Angle([1, 2, 3], u.arcsec), [3, 4, 5] * u.pc)

        assert ax.xaxis.get_units() == u.arcsec
        assert ax.yaxis.get_units() == u.pc 

def test_quantity_subclass():
    """Check that subclasses are recognized.

    This sadly is not done by matplotlib.units itself, though
    there is a PR to change it:
    https://github.com/matplotlib/matplotlib/pull/13536
    """
    plt.figure()

    with quantity_support():
        plt.scatter(Angle([1, 2, 3], u.deg), [3, 4, 5] * u.kg)
        plt.scatter([105, 210, 315] * u.arcsec, [3050, 3025, 3010] * u.g)
        plt.plot(Angle([105, 210, 315], u.arcsec), [3050, 3025, 3010] * u.g)

        assert plt.gca().xaxis.get_units() == u.deg
        assert plt.gca().yaxis.get_units() == u.kg 

def test_compose_fractional_powers():
    # Warning: with a complicated unit, this test becomes very slow;
    # e.g., x = (u.kg / u.s ** 3 * u.au ** 2.5 / u.yr ** 0.5 / u.sr ** 2)
    # takes 3 s
    x = u.m ** 0.5 / u.yr ** 1.5

    factored = x.compose()

    for unit in factored:
        assert x.decompose() == unit.decompose()

    factored = x.compose(units=u.cgs)

    for unit in factored:
        assert x.decompose() == unit.decompose()

    factored = x.compose(units=u.si)

    for unit in factored:
        assert x.decompose() == unit.decompose() 

def calc_radius_from_mass(self, Mp):
        """Helper function for calculating radius given the mass.
        
        Prototype provides only a dummy function that assumes a density of water.
        
        Args:
            Mp (astropy Quantity array):
                Planet mass in units of Earth mass
        
        Returns:
            Rp (astropy Quantity array):
                Planet radius in units of Earth radius
        
        """
        
        rho = 1000*u.kg/u.m**3.
        Rp = ((3.*Mp/rho/np.pi/4.)**(1./3.)).to('earthRad')
        
        return Rp 

def test_units():
    plt.figure()

    with quantity_support():
        buff = io.BytesIO()

        plt.plot([1, 2, 3] * u.m, [3, 4, 5] * u.kg, label='label')
        plt.plot([105, 210, 315] * u.cm, [3050, 3025, 3010] * u.g)
        plt.legend()
        # Also test fill_between, which requires actual conversion to ndarray
        # with numpy >=1.10 (#4654).
        plt.fill_between([1, 3] * u.m, [3, 5] * u.kg, [3050, 3010] * u.g)
        plt.savefig(buff, format='svg')

        assert plt.gca().xaxis.get_units() == u.m
        assert plt.gca().yaxis.get_units() == u.kg 

def test_is_equivalent():
    assert u.m.is_equivalent(u.pc)
    assert u.cycle.is_equivalent(u.mas)
    assert not u.cycle.is_equivalent(u.dimensionless_unscaled)
    assert u.cycle.is_equivalent(u.dimensionless_unscaled,
                                 u.dimensionless_angles())
    assert not (u.Hz.is_equivalent(u.J))
    assert u.Hz.is_equivalent(u.J, u.spectral())
    assert u.J.is_equivalent(u.Hz, u.spectral())
    assert u.pc.is_equivalent(u.arcsecond, u.parallax())
    assert u.arcminute.is_equivalent(u.au, u.parallax())

    # Pass a tuple for multiple possibilities
    assert u.cm.is_equivalent((u.m, u.s, u.kg))
    assert u.ms.is_equivalent((u.m, u.s, u.kg))
    assert u.g.is_equivalent((u.m, u.s, u.kg))
    assert not u.L.is_equivalent((u.m, u.s, u.kg))
    assert not (u.km / u.s).is_equivalent((u.m, u.s, u.kg)) 

def test_gen_mass(self):
        r"""Test gen_mass method.

        Approach: Ensures the output is set, of the correct type, length, and units.
        Check the range of the returned values.  Check that, for this power law, there
        are more small than large masses (for n large).
        """

        plan_pop = self.fixture
        n = 10000
        # call the routine
        masses = plan_pop.gen_mass(n)
        # check the type
        self.assertEqual(type(masses), type(1.0 * u.kg))
        # crude check on the shape (more small than large for this power law)
        midpoint = np.mean(plan_pop.Mprange)
        self.assertGreater(np.count_nonzero(masses < midpoint),
                           np.count_nonzero(masses > midpoint))
        # test some illegal "n" values
        n_list_bad = [-1, '100', 22.5]
        for n in n_list_bad:
            with self.assertRaises(AssertionError):
                masses = plan_pop.gen_mass(n) 

def test_radian(self, function):
            q1 = function(180. * u.degree, 0. * u.arcmin, 0. * u.arcsec)
            assert_allclose(q1.value, np.pi)
            assert q1.unit == u.radian

            q2 = function(0. * u.degree, 30. * u.arcmin, 0. * u.arcsec)
            assert_allclose(q2.value, (30. * u.arcmin).to(u.radian).value)
            assert q2.unit == u.radian

            q3 = function(0. * u.degree, 0. * u.arcmin, 30. * u.arcsec)
            assert_allclose(q3.value, (30. * u.arcsec).to(u.radian).value)

            # the following doesn't make much sense in terms of the name of the
            # routine, but we check it gives the correct result.
            q4 = function(3. * u.radian, 0. * u.arcmin, 0. * u.arcsec)
            assert_allclose(q4.value, 3.)
            assert q4.unit == u.radian

            with pytest.raises(TypeError):
                function(3. * u.m, 2. * u.s, 1. * u.kg) 

def test_comparison_valid_units(self, ufunc):
        q_i1 = np.array([-3.3, 2.1, 10.2]) * u.kg / u.s
        q_i2 = np.array([10., -5., 1.e6]) * u.g / u.Ms
        q_o = ufunc(q_i1, q_i2)
        assert not isinstance(q_o, u.Quantity)
        assert q_o.dtype == bool
        assert np.all(q_o == ufunc(q_i1.value, q_i2.to_value(q_i1.unit)))
        q_o2 = ufunc(q_i1 / q_i2, 2.)
        assert not isinstance(q_o2, u.Quantity)
        assert q_o2.dtype == bool
        assert np.all(q_o2 == ufunc((q_i1 / q_i2)
                                    .to_value(u.dimensionless_unscaled), 2.))
        # comparison with 0., inf, nan is OK even for dimensional quantities
        # (though ignore numpy runtime warnings for comparisons with nan).
        with catch_warnings(RuntimeWarning):
            for arbitrary_unit_value in (0., np.inf, np.nan):
                ufunc(q_i1, arbitrary_unit_value)
                ufunc(q_i1, arbitrary_unit_value*np.ones(len(q_i1)))
            # and just for completeness
            ufunc(q_i1, np.array([0., np.inf, np.nan])) 

def test_unit_mismatch(self):

        q_len = u.Quantity([1], u.km)
        q_nonlen = u.Quantity([1], u.kg)

        with pytest.raises(u.UnitsError) as exc:
            s1 = CartesianRepresentation(x=q_nonlen, y=q_len, z=q_len)
        assert exc.value.args[0] == "x, y, and z should have matching physical types"

        with pytest.raises(u.UnitsError) as exc:
            s1 = CartesianRepresentation(x=q_len, y=q_nonlen, z=q_len)
        assert exc.value.args[0] == "x, y, and z should have matching physical types"

        with pytest.raises(u.UnitsError) as exc:
            s1 = CartesianRepresentation(x=q_len, y=q_len, z=q_nonlen)
        assert exc.value.args[0] == "x, y, and z should have matching physical types" 

def test_complicated_operation(self):
        """ Perform a more complicated test """
        from astropy.units import imperial

        # Multiple units
        distance = u.Quantity(15., u.meter)
        time = u.Quantity(11., u.second)

        velocity = (distance / time).to(imperial.mile / u.hour)
        assert_array_almost_equal(
            velocity.value, 3.05037, decimal=5)

        G = u.Quantity(6.673E-11, u.m ** 3 / u.kg / u.s ** 2)
        new_q = ((1. / (4. * np.pi * G)).to(u.pc ** -3 / u.s ** -2 * u.kg))

        # Area
        side1 = u.Quantity(11., u.centimeter)
        side2 = u.Quantity(7., u.centimeter)
        area = side1 * side2
        assert_array_almost_equal(area.value, 77., decimal=15)
        assert area.unit == u.cm * u.cm 

def test_invariant_twoarg_array(self, ufunc):

        q_i1 = np.array([-3.3, 2.1, 10.2]) * u.kg / u.s
        q_i2 = np.array([10., -5., 1.e6]) * u.g / u.us
        q_o = ufunc(q_i1, q_i2)
        assert isinstance(q_o, u.Quantity)
        assert q_o.unit == q_i1.unit
        assert_allclose(q_o.value, ufunc(q_i1.value, q_i2.to_value(q_i1.unit))) 

def test_comparison_ufuncs_inplace(self, ufunc):
        q_i1 = np.array([-3.3, 2.1, 10.2]) * u.kg / u.s
        q_i2 = np.array([10., -5., 1.e6]) * u.g / u.Ms
        check = np.empty(q_i1.shape, bool)
        ufunc(q_i1.value, q_i2.to_value(q_i1.unit), out=check)

        result = np.empty(q_i1.shape, bool)
        q_o = ufunc(q_i1, q_i2, out=result)
        assert q_o is result
        assert type(q_o) is np.ndarray
        assert q_o.dtype == bool
        assert np.all(q_o == check) 

def test_unit_division_by_string():
    """Check that multiplication with strings produces the correct unit."""
    u1 = u.cm
    us = 'kg'
    assert us / u1 == u.Unit(us) / u1
    assert u1 / us == u1 / u.Unit(us) 

def test_invariant_array(self, ufunc):

        q_i = np.array([-3.3, 2.1, 10.2]) * u.kg / u.s
        q_o = ufunc(q_i)
        assert isinstance(q_o, u.Quantity)
        assert q_o.unit == q_i.unit
        assert np.all(q_o.value == ufunc(q_i.value)) 

def test_enable_unit_groupings():
    from astropy.units import cds

    with cds.enable():
        assert cds.geoMass in u.kg.find_equivalent_units()

    from astropy.units import imperial
    with imperial.enable():
        assert imperial.inch in u.m.find_equivalent_units() 

def test_self_compose():
    unit = u.kg * u.s

    assert len(unit.compose(units=[u.g, u.s])) == 1 

def test_jv_invalid_units(self, function):
            # Can't use jv() with non-dimensionless quantities
            with pytest.raises(TypeError) as exc:
                function(1. * u.kg, 3. * u.m / u.s)
            assert exc.value.args[0] == ("Can only apply '{}' function to "
                                         "dimensionless quantities"
                                         .format(function.__name__)) 

def test_unit_decomposition(self):
        lu = u.mag(u.Jy)
        assert lu.decompose() == u.mag(u.Jy.decompose())
        assert lu.decompose().physical_unit.bases == [u.kg, u.s]
        assert lu.si == u.mag(u.Jy.si)
        assert lu.si.physical_unit.bases == [u.kg, u.s]
        assert lu.cgs == u.mag(u.Jy.cgs)
        assert lu.cgs.physical_unit.bases == [u.g, u.s] 

def test_str_unit_typo():
    @u.quantity_input
    def myfunc_args(x: "kilograam"):
        return x

    with pytest.raises(ValueError):
        result = myfunc_args(u.kg) 

def test_round(self):
        q1 = np.array([1.253, 2.253, 3.253]) * u.kg
        assert np.all(np.round(q1) == np.array([1, 2, 3]) * u.kg)
        assert np.all(np.round(q1, decimals=2) ==
                      np.round(q1.value, decimals=2) * u.kg)
        assert np.all(q1.round(decimals=2) ==
                      q1.value.round(decimals=2) * u.kg) 

def test_round_inplace(self):
        q1 = np.array([1.253, 2.253, 3.253]) * u.kg
        qi = np.zeros(3) * u.s
        a = q1.round(decimals=2, out=qi)
        assert a is qi
        assert np.all(q1.round(decimals=2) == qi) 

def test_equivalent_units():
    from astropy.units import imperial
    with u.add_enabled_units(imperial):
        units = u.g.find_equivalent_units()
        units_set = set(units)
        match = set(
            [u.M_e, u.M_p, u.g, u.kg, u.solMass, u.t, u.u, u.M_earth,
             u.M_jup, imperial.oz, imperial.lb, imperial.st, imperial.ton,
             imperial.slug])
        assert units_set == match

    r = repr(units)
    assert r.count('\n') == len(units) + 2 

def test_invalid_equivalency():
    with pytest.raises(ValueError):
        u.m.to(u.kg, equivalencies=[(u.m,)])

    with pytest.raises(ValueError):
        u.m.to(u.kg, equivalencies=[(u.m, 5.0)]) 

def test_irrelevant_equivalency():
    with pytest.raises(u.UnitsError):
        u.m.to(u.kg, equivalencies=[(u.m, u.l)]) 

def test_value_array(tmpdir):
    testval = [3.14159]
    testunit = units.kg
    yaml = """
quantity: !unit/quantity-1.1.0
    value: !core/ndarray-1.0.0 {}
    unit: {}
""".format(testval, testunit)

    quantity = units.Quantity(testval, unit=testunit)
    roundtrip_quantity(yaml, quantity) 

def test_unit_non_length(self):

        s1 = CartesianRepresentation(x=1 * u.kg, y=2 * u.kg, z=3 * u.kg)

        s2 = CartesianRepresentation(x=1 * u.km / u.s, y=2 * u.km / u.s, z=3 * u.km / u.s)

        banana = u.def_unit('banana')
        s3 = CartesianRepresentation(x=1 * banana, y=2 * banana, z=3 * banana) 

def mass_dec(self, dF_lateral, t_int):
        """Returns mass_used and deltaV 
        
        The values returned by this method are used to decrement spacecraft 
        mass for station-keeping.
        
        Args:
            dF_lateral (astropy Quantity):
                Lateral disturbance force in units of N
            t_int (astropy Quantity):
                Integration time in units of day
                
        Returns:
            tuple:
            intMdot (astropy Quantity):
                Mass flow rate in units of kg/s
            mass_used (astropy Quantity):
                Mass used in station-keeping units of kg
            deltaV (astropy Quantity):
                Change in velocity required for station-keeping in units of km/s
        
        """
        
        intMdot = (1./np.cos(np.radians(45))*np.cos(np.radians(5))*
                dF_lateral/const.g0/self.skIsp).to('kg/s')
        mass_used = (intMdot*t_int).to('kg')
        deltaV = (dF_lateral/self.scMass*t_int).to('km/s')
        
        return intMdot, mass_used, deltaV 

def mass_dec_sk(self, TL, sInd, currentTime, t_int):
        """Returns mass_used, deltaV and disturbance forces
        
        This method calculates all values needed to decrement spacecraft mass
        for station-keeping.
        
        Args:
            TL (TargetList module):
                TargetList class object
            sInd (integer):
                Integer index of the star of interest
            currentTime (astropy Time):
                Current absolute mission time in MJD
            t_int (astropy Quantity):
                Integration time in units of day
                
        Returns:
            tuple:
            dF_lateral (astropy Quantity):
                Lateral disturbance force in units of N
            dF_axial (astropy Quantity):
                Axial disturbance force in units of N
            intMdot (astropy Quantity):
                Mass flow rate in units of kg/s
            mass_used (astropy Quantity):
                Mass used in station-keeping units of kg
            deltaV (astropy Quantity):
                Change in velocity required for station-keeping in units of km/s
        
        """
        
        dF_lateral, dF_axial = self.distForces(TL, sInd, currentTime)
        intMdot, mass_used, deltaV = self.mass_dec(dF_lateral, t_int)
        
        return dF_lateral, dF_axial, intMdot, mass_used, deltaV 

def log_occulterResults(self,DRM,slewTimes,sInd,sd,dV):
        """Updates the given DRM to include occulter values and results
        
        Args:
            DRM (dict):
                Design Reference Mission, contains the results of one complete
                observation (detection and characterization)
            slewTimes (astropy Quantity):
                Time to transfer to new star line of sight in units of days
            sInd (integer):
                Integer index of the star of interest
            sd (astropy Quantity):
                Angular separation between stars in rad
            dV (astropy Quantity):
                Delta-V used to transfer to new star line of sight in units of m/s
                
        Returns:
            dict:
                Design Reference Mission dictionary, contains the results of one complete
                observation (detection and characterization)
        
        """
        
        DRM['slew_time'] = slewTimes.to('day')
        DRM['slew_angle'] = sd.to('deg')
        
        slew_mass_used = slewTimes*self.defburnPortion*self.flowRate
        DRM['slew_dV'] = (slewTimes*self.ao*self.defburnPortion).to('m/s')
        DRM['slew_mass_used'] = slew_mass_used.to('kg')
        self.scMass = self.scMass - slew_mass_used
        DRM['scMass'] = self.scMass.to('kg')
        
        return DRM