def test_power_to_dimensionless_quantities(self):
"""I can raise quantities to dimensionless quantities."""
L1 = Distance("3m")
L2 = Distance("6m")
A = L1*L2
L3 = A**(L1/L2)
self.assertEqual(L3['m'], (3*6)**(1/2))
def test_distance_subtracting(self):
"""Test subtracting distances."""
d1 = Distance("10 m")
d2 = Distance("3 km")
d3 = d2 - d1
self.assertEqual(d1.dimension, d3.dimension) # type is the same
self.assertEqual(d3['m'], 2990)
def test_distance_adding(self):
"""Test adding distances."""
d1 = Distance("10 m")
d2 = Distance("3 km")
d3 = d1 + d2
self.assertEqual(d1.dimension, d3.dimension) # type is the same
self.assertEqual(d3['m'], 3010)
def test_creating_from_other_distance(self):
"""I can create a distance from another."""
d1 = Distance("10 m")
d2 = Distance(d1)
self.assertEqual(d1, d2)
d2['m'] = 2
self.assertEqual(d2['m'], 2)
self.assertEqual(d1['m'], 10)
def test_simple_speeds(self):
"""Create a few speeds and check the value."""
s = Speed('1 mi/hr')
self.assertEqual(s['mi/hr'], 1)
s['miles/hr'] = 2.5
self.assertEqual(s['mi/hr'], 2.5)
self.assertEqual(s['m/s'], 2.5*Distance('1mi')['m']/Time('1hr')['s'])
def test_comparison_of_combined_units(self):
d = Distance("10m")
t = Time("5s")
self.assertFalse(d.dimension == t.dimension)
self.assertRaises(IncompatibleUnitsError, d.__lt__, t)
self.assertRaises(IncompatibleUnitsError, d.__gt__, t)
self.assertRaises(IncompatibleUnitsError, d.__le__, t)
self.assertRaises(IncompatibleUnitsError, d.__ge__, t)
def test_create_simple_distances(self):
"""Simple distances."""
# Check consistency
for unit,meters in self.meters_in.iteritems():
d = Distance('1' + unit) # create "1x" where x is the unit
self.assertEqual(d['m'], meters) # the meters should be correct
# Check creating from other distances
d1 = Distance("1 m")
d2 = Distance(d1)
self.assertEqual(d1['m'], d2['m'])
# Check creating from another quantity with same dimensions
d1 = PhysicalQuantity(Dimension(L = 1), "1 m")
d2 = Distance(d1)
self.assertEqual(d1['m'], d2['m'])
# Check creating from another quantity with different dimensions
d1 = PhysicalQuantity(Dimension(T = 1), "1 s")
self.assertRaises(IncompatibleUnitsError, Distance, d1)
def test_multiplication_and_division_of_combined_units(self):
d = Distance("10m")
t = Time("5s")
s1 = d/t # division
s2 = Speed("2m/s")
self.assertEqual(s1.dimension, s2.dimension)
self.assertEqual(s1, s2)
d2 = s2*t # multiplication
self.assertEqual(d2, d)
def test_check_known_pace(self):
"""Check pace for some speeds."""
# speed, distance for pace, pace
known_values = [
['1 m/s', '1 km', '1000s'],
['1 meters/s', '1 km', '1000s'],
['1 mi/hr', '1 mi', '1 hr']
]
for speed, distance, pace in known_values:
s, d, t = Speed(speed), Distance(distance), Time(pace)
self.assertEqual(s.pace(d)['s'], t['s']) # the seconds should be correct
def test_power(self):
"""I can raise quantities to integer or fractional powers."""
L = Distance("3m")
A = L**2
self.assertEqual(A, L*L)
V = L**3
self.assertEqual(V, L*L*L)
L2 = A**0.5
self.assertEqual(L2, L)
# type guessing works
m = Mass("7 kg")
v = Speed("11 m/s")
E = 1/2*m*v**2
self.assertEqual(E['J'], 1/2*7*11*11)
def test_type_coercion_on_addition_and_subtraction(self):
"""A PhysicalQuantity, when added/subtracted to/from a Time becomes a Time."""
t1 = Time("5s")
t2 = PhysicalQuantity(Dimension(T = 1), "1 min")
self.assertTrue(type(t1) != type(t2)) # sanity check before the real check
# coercion on the left & right
self.assertEqual(type(t1 + t2), type(t1))
self.assertEqual(type(t2 + t1), type(t1))
self.assertEqual(type(t1 - t2), type(t1))
self.assertEqual(type(t2 - t1), type(t1))
# A more complex example
s = Speed("3 m/s")
d = Distance("4 m")
t = Time("4 s")
self.assertEqual(type(s + d/t), Speed)
self.assertEqual(type(d/t + s), Speed)
def test_multiplication_and_division_involving_scalars(self):
d1 = Distance("10m")
d2 = d1/2
self.assertEqual(type(d2), Distance)
self.assertEqual(d2['m'], 5)
d3 = d1*2 # multiply on the right
self.assertEqual(type(d3), Distance)
self.assertEqual(d3['m'], 20)
d4 = 2*d1 # multiply on the left
self.assertEqual(type(d4), Distance)
self.assertEqual(d4['m'], 20)
t1 = Time("4hr")
rate = 8/t1
self.assertEqual(rate["1/hr"], 2)
t2 = 8/rate
self.assertEqual(type(t2), Time)
self.assertEqual(t2, t1)
def test_addition_and_subtraction_involving_scalars(self):
v1 = Dimensionless("1")
v2 = v1 + 2
self.assertEqual(type(v2), type(v1))
self.assertEqual(v2['1'], 3)
v3 = 2 + v1
self.assertEqual(type(v3), type(v1))
self.assertEqual(v3['1'], 3)
v4 = v1 - 3
self.assertEqual(type(v4), type(v1))
self.assertEqual(v4['1'], -2)
v5 = 3 - v1
self.assertEqual(type(v5), type(v1))
self.assertEqual(v5['1'], 2)
# this won't work with other dimensions
d = Distance("3m")
self.assertRaises(IncompatibleUnitsError, d.__add__, 4)
self.assertRaises(IncompatibleUnitsError, d.__radd__, 4)
self.assertRaises(IncompatibleUnitsError, d.__sub__, 4)
self.assertRaises(IncompatibleUnitsError, d.__rsub__, 4)
def test_type_guessing_in_general(self):
"""The library should find the proper type depending on dimensions."""
d = Distance("10m")
t = Time("5s")
self.assertEqual(type(d/t), Speed)
v = Speed("10mi/hr")
self.assertEqual(type(v*t), Distance)
# charge density
rho = PhysicalQuantity(Dimension(L = -3, Q = 1), "4C/m^3")
q = rho*d*d*d
self.assertEqual(type(q), Charge)
self.assertEqual(q['C'], 4000)
# Note: this doesn't work for a quantity explicitly defined as a PhysicalQuantity
T1 = Temperature("3 K")
T2 = PhysicalQuantity(Dimension(Theta = 1), "3 K")
self.assertEqual(T1, T2)
self.assertEqual(type(T1), Temperature)
self.assertEqual(type(T2), PhysicalQuantity)
# But a multiplication or division by a dimensionless quantity should fix that
T3 = T2/PhysicalQuantity(Dimension(), "1")
self.assertEqual(type(T3), Temperature)
def test_for_distance_equality(self):
"""Test that distances are only compared by length."""
d1 = Distance("1m")
d2 = Distance("0.001km")
self.assertEqual(d1['m'], d2['m']) # sanity check before the real test
self.assertEqual(d1, d2)
def test_addition_and_subtraction_of_combined_units(self):
d = Distance("10m")
t = Time("5s")
self.assertRaises(IncompatibleUnitsError, d.__add__, t)
self.assertRaises(IncompatibleUnitsError, d.__sub__, t)
def test_consistency(self):
"""In its own units, the value should be 1."""
for unit in self.meters_in.keys():
d = Distance('1' + unit) # create "1x" where x is the unit
self.assertEqual(d[unit], 1)
