def __test_bulk_cross_elasticity(original_quantity, new_quantity,
original_price, new_price, expected_ced,
repetition_count):
original_quantity = np.repeat(original_quantity, repetition_count)
new_quantity = np.repeat(new_quantity, repetition_count)
original_price = np.repeat(original_price, repetition_count)
new_price = np.repeat(new_price, repetition_count)
expected_ced = np.repeat(expected_ced, repetition_count)
ced = calculate_cross_elasticity(original_quantity, new_quantity,
original_price, new_price)
assert expected_ced == approx(ced)
def test_unrelated_cross_elasticity():
original_quantity = new_quantity = 1000
original_price = 20
new_price = 30
expected_ced = 0
ced = calculate_cross_elasticity(original_quantity, new_quantity,
original_price, new_price)
assert expected_ced == approx(ced)
__test_bulk_cross_elasticity(original_quantity, new_quantity,
original_price, new_price, expected_ced, 100)
def test_complimentary_cross_elasticity():
original_quantity = 1000
new_quantity = 1100
original_price = 100
new_price = 80
expected_ced = -0.4285714286
ced = calculate_cross_elasticity(original_quantity, new_quantity,
original_price, new_price)
assert expected_ced == approx(ced)
__test_bulk_cross_elasticity(original_quantity, new_quantity,
original_price, new_price, expected_ced, 100)
def test_substitute_cross_elasticity():
original_quantity = 200
new_quantity = 400
original_price = 1000
new_price = 1050
# (200 / 300) / (50 / 1025)
expected_ced = 13.66666666666666
ced = calculate_cross_elasticity(original_quantity, new_quantity,
original_price, new_price)
assert expected_ced == approx(ced)
__test_bulk_cross_elasticity(original_quantity, new_quantity,
original_price, new_price, expected_ced, 100)
def test_mismatched_arrays():
with raises(ValueError):
calculate_cross_elasticity(np.random.random(100), np.random.random(10),
np.random.random(100),
np.random.random(100))
with raises(ValueError):
calculate_cross_elasticity(np.random.random(100),
np.random.random(100), np.random.random(10),
np.random.random(100))
with raises(ValueError):
calculate_cross_elasticity(np.random.random(100),
np.random.random(100),
np.random.random(100), np.random.random(10))
with raises(ValueError):
calculate_cross_elasticity(np.random.random(10),
np.random.random(1001),
np.random.random(103), np.random.random(9))