def test_create_deviation(u_image, u_gain, u_readnoise, expect_success):
ccd_data = ccd_data_func(data_size=10, data_mean=100)
ccd_data.unit = u_image
if u_gain is not None:
gain = 2.0 * u_gain
else:
gain = None
readnoise = 5 * u_readnoise
if expect_success:
ccd_var = create_deviation(ccd_data, gain=gain, readnoise=readnoise)
assert ccd_var.uncertainty.array.shape == (10, 10)
assert ccd_var.uncertainty.array.size == 100
assert ccd_var.uncertainty.array.dtype == np.dtype(float)
if gain is not None:
expected_var = np.sqrt(2 * ccd_data.data + 5**2) / 2
else:
expected_var = np.sqrt(ccd_data.data + 5**2)
np.testing.assert_array_equal(ccd_var.uncertainty.array, expected_var)
assert ccd_var.unit == ccd_data.unit
# Uncertainty should *not* have any units -- does it?
with pytest.raises(AttributeError):
ccd_var.uncertainty.array.unit
else:
with pytest.raises(u.UnitsError):
ccd_var = create_deviation(ccd_data,
gain=gain,
readnoise=readnoise)
def test_flat_correct_deviation():
ccd_data = ccd_data_func(data_scale=10, data_mean=300)
size = ccd_data.shape[0]
ccd_data.unit = u.electron
ccd_data = create_deviation(ccd_data, readnoise=5 * u.electron)
# Create the flat
data = 2 * np.ones((size, size))
flat = CCDData(data, meta=fits.header.Header(), unit=ccd_data.unit)
flat = create_deviation(flat, readnoise=0.5 * u.electron)
ccd_data = flat_correct(ccd_data, flat)
def test_create_deviation_does_not_change_input():
ccd_data = ccd_data_func()
original = ccd_data.copy()
ccd = create_deviation(ccd_data,
gain=5 * u.electron / u.adu,
readnoise=10 * u.electron)
np.testing.assert_array_equal(original.data, ccd_data.data)
assert original.unit == ccd_data.unit
def test_create_deviation_from_negative():
ccd_data = ccd_data_func(data_mean=0, data_scale=10)
ccd_data.unit = u.electron
readnoise = 5 * u.electron
ccd_var = create_deviation(ccd_data,
gain=None,
readnoise=readnoise,
disregard_nan=False)
np.testing.assert_array_equal(ccd_data.data < 0,
np.isnan(ccd_var.uncertainty.array))
def test_create_deviation_from_negative():
ccd_data = ccd_data_func(data_mean=0, data_scale=10)
ccd_data.unit = u.electron
readnoise = 5 * u.electron
ccd_var = create_deviation(ccd_data,
gain=None,
readnoise=readnoise,
disregard_nan=True)
mask = (ccd_data.data < 0)
ccd_data.data[mask] = 0
expected_var = np.sqrt(ccd_data.data + readnoise.value**2)
np.testing.assert_array_equal(ccd_var.uncertainty.array, expected_var)
def test_linear_gain_unit_keyword():
ccd_data = ccd_data_func()
# The data values should be positive, so the poisson noise calculation
# works without throwing warnings
ccd_data.data = np.absolute(ccd_data.data)
ccd_data = create_deviation(ccd_data, readnoise=1.0 * u.adu)
orig_data = ccd_data.data
gain = 3.0
gain_unit = u.electron / u.adu
ccd = gain_correct(ccd_data, gain, gain_unit=gain_unit)
np.testing.assert_array_almost_equal_nulp(ccd.data, gain * orig_data)
np.testing.assert_array_almost_equal_nulp(
ccd.uncertainty.array, gain * ccd_data.uncertainty.array)
assert ccd.unit == ccd_data.unit * gain_unit
def test_create_deviation_keywords_must_have_unit():
ccd_data = ccd_data_func()
# Gain must have units if provided
with pytest.raises(TypeError):
create_deviation(ccd_data, gain=3)
# Readnoise must have units
with pytest.raises(TypeError):
create_deviation(ccd_data, readnoise=5)
# Readnoise must be provided
with pytest.raises(ValueError):
create_deviation(ccd_data)
def test_linear_gain_correct(gain):
ccd_data = ccd_data_func()
# The data values should be positive, so the poisson noise calculation
# works without throwing warnings
ccd_data.data = np.absolute(ccd_data.data)
ccd_data = create_deviation(ccd_data, readnoise=1.0 * u.adu)
ccd_data.meta['gainval'] = 3.0
orig_data = ccd_data.data
ccd = gain_correct(ccd_data, gain)
if isinstance(gain, Keyword):
gain = gain.value # convert to Quantity...
try:
gain_value = gain.value
except AttributeError:
gain_value = gain
np.testing.assert_array_almost_equal_nulp(ccd.data, gain_value * orig_data)
np.testing.assert_array_almost_equal_nulp(
ccd.uncertainty.array, gain_value * ccd_data.uncertainty.array)
if isinstance(gain, u.Quantity):
assert ccd.unit == ccd_data.unit * gain.unit
else:
assert ccd.unit == ccd_data.unit