def test_first_derivative_2d(deriv_2d_data):
"""Test first_derivative with a full 2D array."""
df_dx = first_derivative(deriv_2d_data.f, x=deriv_2d_data.x, axis=1)
df_dx_analytic = np.tile(2 * deriv_2d_data.a * (deriv_2d_data.x - deriv_2d_data.x0),
(deriv_2d_data.f.shape[0], 1))
assert_array_almost_equal(df_dx, df_dx_analytic, 5)
df_dy = first_derivative(deriv_2d_data.f, x=deriv_2d_data.y, axis=0)
# Repeat each row, then flip to get variation along rows
df_dy_analytic = np.tile(2 * deriv_2d_data.b * (deriv_2d_data.y - deriv_2d_data.y0),
(deriv_2d_data.f.shape[1], 1)).T
assert_array_almost_equal(df_dy, df_dy_analytic, 5)
def test_first_derivative_2d(deriv_2d_data):
"""Test first_derivative with a full 2D array."""
df_dx = first_derivative(deriv_2d_data.f, x=deriv_2d_data.x, axis=1)
df_dx_analytic = np.tile(2 * deriv_2d_data.a * (deriv_2d_data.x - deriv_2d_data.x0),
(deriv_2d_data.f.shape[0], 1))
assert_array_almost_equal(df_dx, df_dx_analytic, 5)
df_dy = first_derivative(deriv_2d_data.f, x=deriv_2d_data.y, axis=0)
# Repeat each row, then flip to get variation along rows
df_dy_analytic = np.tile(2 * deriv_2d_data.b * (deriv_2d_data.y - deriv_2d_data.y0),
(deriv_2d_data.f.shape[1], 1)).T
assert_array_almost_equal(df_dy, df_dy_analytic, 5)
def test_first_derivative(deriv_1d_data):
"""Test first_derivative with a simple 1D array."""
dv_dx = first_derivative(deriv_1d_data.values, x=deriv_1d_data.x)
# Worked by hand and taken from Chapra and Canale 23.2
truth = np.array([-1.333333, -1.06666667, -0.5333333]) * units('delta_degC / cm')
assert_array_almost_equal(dv_dx, truth, 5)
def test_first_derivative(deriv_1d_data):
"""Test first_derivative with a simple 1D array."""
dv_dx = first_derivative(deriv_1d_data.values, x=deriv_1d_data.x)
# Worked by hand and taken from Chapra and Canale 23.2
truth = np.array([-1.333333, -1.06666667, -0.5333333]) * units('delta_degC / cm')
assert_array_almost_equal(dv_dx, truth, 5)
def test_first_derivative_xarray_pint_conversion(test_da_lonlat):
"""Test first derivative with implicit xarray to pint quantity conversion."""
dx, _ = grid_deltas_from_dataarray(test_da_lonlat)
deriv = first_derivative(test_da_lonlat, delta=dx, axis=-1)
truth = np.array([[[-3.30782978e-06] * 4, [-3.42816074e-06] * 4, [-3.57012948e-06] * 4,
[-3.73759364e-06] * 4]] * 3) * units('kelvin / meter')
assert_array_almost_equal(deriv, truth, 12)
def test_first_derivative_xarray_pint_conversion(test_da_lonlat):
"""Test first derivative with implicit xarray to pint quantity conversion."""
dx, _ = grid_deltas_from_dataarray(test_da_lonlat)
deriv = first_derivative(test_da_lonlat, delta=dx, axis=-1)
truth = np.array([[[-3.30782978e-06] * 4, [-3.42816074e-06] * 4, [-3.57012948e-06] * 4,
[-3.73759364e-06] * 4]] * 3) * units('kelvin / meter')
assert_array_almost_equal(deriv, truth, 12)
def test_first_derivative_xarray_time_and_default_axis(test_da_xy):
"""Test first derivative with an xarray.DataArray over time as default first dimension."""
deriv = first_derivative(test_da_xy)
truth = xr.full_like(test_da_xy, -0.000777000777)
truth.attrs['units'] = 'kelvin / second'
xr.testing.assert_allclose(deriv, truth)
assert deriv.metpy.units == truth.metpy.units
def test_first_derivative_xarray_time_and_default_axis(test_da_xy):
"""Test first derivative with an xarray.DataArray over time as default first dimension."""
deriv = first_derivative(test_da_xy)
truth = xr.full_like(test_da_xy, -0.000777000777)
truth.attrs['units'] = 'kelvin / second'
xr.testing.assert_allclose(deriv, truth)
assert deriv.metpy.units == truth.metpy.units
def kinematics(u, v, thetae, dx, dy, lats, smooth=False, sigma=1):
'''
Use metpy functions to calculate various kinematics, given 2d numpy arrays as inputs. X and y grid spacing, as well as a 2d array of latitudes is also required.
Option to smooth the thetae field before calculating front diagnostics (recommended), with addition "sigma" parameter controlling the smoothness (see scipy docs)
'''
if smooth:
thetae = gaussian_filter(thetae, sigma)
#Kinematics
ddy_thetae = mpcalc.first_derivative(thetae, delta=dy, axis=0)
ddx_thetae = mpcalc.first_derivative(thetae, delta=dx, axis=1)
mag_thetae = np.sqrt(ddx_thetae**2 + ddy_thetae**2)
div = mpcalc.divergence(u, v, dx, dy)
strch_def = mpcalc.stretching_deformation(u, v, dx, dy)
shear_def = mpcalc.shearing_deformation(u, v, dx, dy)
tot_def = mpcalc.total_deformation(u, v, dx, dy)
psi = 0.5 * np.arctan2(shear_def, strch_def)
beta = np.arcsin(
(-ddx_thetae * np.cos(psi) - ddy_thetae * np.sin(psi)) / mag_thetae)
vo = mpcalc.vorticity(u, v, dx, dy)
conv = -div * 1e5
F = np.array(0.5 * mag_thetae * (tot_def * np.cos(2 * beta) - div) *
1.08e4 * 1e5)
Fn = np.array(0.5 * mag_thetae * (div - tot_def * np.cos(2 * beta)) *
1.08e4 * 1e5)
Fs = np.array(0.5 * mag_thetae * (vo + tot_def * np.sin(2 * beta)) *
1.08e4 * 1e5)
icon = np.array(0.5 * (tot_def - div) * 1e5)
vgt = np.array(np.sqrt(div**2 + vo**2 + tot_def**2) * 1e5)
#TFP
ddx_thetae_scaled = ddx_thetae / mag_thetae
ddy_thetae_scaled = ddy_thetae / mag_thetae
ddy_mag_thetae = -1 * mpcalc.first_derivative(mag_thetae, delta=dy, axis=0)
ddx_mag_thetae = -1 * mpcalc.first_derivative(mag_thetae, delta=dx, axis=1)
tfp = ddx_mag_thetae * ddx_thetae_scaled + ddy_mag_thetae * ddy_thetae_scaled
ddy_tfp = mpcalc.first_derivative(tfp, delta=dy, axis=0)
ddx_tfp = mpcalc.first_derivative(tfp, delta=dx, axis=1)
mag_tfp = np.sqrt(ddx_tfp**2 + ddy_tfp**2)
v_f = (u * units.units("m/s")) * (ddx_tfp / mag_tfp) + (
v * units.units("m/s")) * (ddy_tfp / mag_tfp)
#Extra condition
ddy_ddy_mag_te = mpcalc.first_derivative(-1 * ddy_mag_thetae,
delta=dy,
axis=0)
ddx_ddx_mag_te = mpcalc.first_derivative(-1 * ddx_mag_thetae,
delta=dx,
axis=1)
cond = ddy_ddy_mag_te + ddx_ddx_mag_te
return [F, Fn, Fs, icon, vgt, conv, vo*1e5, \
np.array(tfp.to("km^-2")*(100*100)), np.array(mag_thetae.to("km^-1"))*100, np.array(v_f), thetae, cond]
def test_first_derivative_masked():
"""Test that first_derivative properly propagates masks."""
data = np.ma.arange(7)
data[3] = np.ma.masked
df_dx = first_derivative(data, delta=1)
truth = np.ma.array([1., 1., 1., 1., 1., 1., 1.],
mask=[False, False, True, True, True, False, False])
assert_array_almost_equal(df_dx, truth)
assert_array_equal(df_dx.mask, truth.mask)
def test_first_derivative_masked():
"""Test that first_derivative properly propagates masks."""
data = np.ma.arange(7)
data[3] = np.ma.masked
df_dx = first_derivative(data, delta=1)
truth = np.ma.array([1., 1., 1., 1., 1., 1., 1.],
mask=[False, False, True, True, True, False, False])
assert_array_almost_equal(df_dx, truth)
assert_array_equal(df_dx.mask, truth.mask)
def test_first_derivative_xarray_lonlat(test_da_lonlat):
"""Test first derivative with an xarray.DataArray on a lonlat grid in each axis usage."""
deriv = first_derivative(test_da_lonlat,
axis='lon') # dimension coordinate name
deriv_alt1 = first_derivative(test_da_lonlat, axis='x') # axis type
deriv_alt2 = first_derivative(test_da_lonlat, axis=-1) # axis number
# Build the xarray of the desired values
partial = xr.DataArray(np.array(
[-3.30782978e-06, -3.42816074e-06, -3.57012948e-06, -3.73759364e-06]),
coords=(('lat', test_da_lonlat['lat']), ))
_, truth = xr.broadcast(test_da_lonlat, partial)
truth.coords['crs'] = test_da_lonlat['crs']
truth.attrs['units'] = 'kelvin / meter'
# Assert result matches expectation
xr.testing.assert_allclose(deriv, truth)
assert deriv.metpy.units == truth.metpy.units
# Assert alternative specifications give same result
xr.testing.assert_identical(deriv_alt1, deriv)
xr.testing.assert_identical(deriv_alt2, deriv)
def test_first_derivative_xarray_lonlat(test_da_lonlat):
"""Test first derivative with an xarray.DataArray on a lonlat grid in each axis usage."""
deriv = first_derivative(test_da_lonlat, axis='lon') # dimension coordinate name
deriv_alt1 = first_derivative(test_da_lonlat, axis='x') # axis type
deriv_alt2 = first_derivative(test_da_lonlat, axis=-1) # axis number
# Build the xarray of the desired values
partial = xr.DataArray(
np.array([-3.30782978e-06, -3.42816074e-06, -3.57012948e-06, -3.73759364e-06]),
coords=(('lat', test_da_lonlat['lat']),)
)
_, truth = xr.broadcast(test_da_lonlat, partial)
truth.coords['crs'] = test_da_lonlat['crs']
truth.attrs['units'] = 'kelvin / meter'
# Assert result matches expectation
xr.testing.assert_allclose(deriv, truth)
assert deriv.metpy.units == truth.metpy.units
# Assert alternative specifications give same result
xr.testing.assert_identical(deriv_alt1, deriv)
xr.testing.assert_identical(deriv_alt2, deriv)
def test_first_derivative_xarray_time_subsecond_precision():
"""Test time derivative with an xarray.DataArray where subsecond precision is needed."""
test_da = xr.DataArray([299.5, 300, 300.5],
dims='time',
coords={'time': np.array(['2019-01-01T00:00:00.0',
'2019-01-01T00:00:00.1',
'2019-01-01T00:00:00.2'],
dtype='datetime64[ms]')},
attrs={'units': 'kelvin'})
deriv = first_derivative(test_da)
truth = xr.full_like(test_da, 5.)
truth.attrs['units'] = 'kelvin / second'
xr.testing.assert_allclose(deriv, truth)
assert deriv.metpy.units == truth.metpy.units
lon, lat = np.meshgrid(lons, lats)
# Calculate Geostrophic Wind from Analytic Heights
f = mpcalc.coriolis_parameter(lat * units('degrees'))
dx, dy = mpcalc.lat_lon_grid_deltas(lons, lats)
ugeo, vgeo = mpcalc.geostrophic_wind(Z * units.meter,
f,
dx,
dy,
dim_order='yx')
# Get the wind direction for each point
wdir = mpcalc.wind_direction(ugeo, vgeo)
# Compute the Gradient Wind via an approximation
dydx = mpcalc.first_derivative(Z, delta=dx, axis=1)
d2ydx2 = mpcalc.first_derivative(dydx, delta=dx, axis=1)
R = ((1 + dydx.m**2)**(3. / 2.)) / d2ydx2.m
geo_mag = mpcalc.wind_speed(ugeo, vgeo)
grad_mag = geo_mag.m - (geo_mag.m**2) / (f.magnitude * R)
ugrad, vgrad = mpcalc.wind_components(grad_mag * units('m/s'), wdir)
# Calculate Ageostrophic wind
uageo = ugrad - ugeo
vageo = vgrad - vgeo
# Compute QVectors
uqvect, vqvect = mpcalc.q_vector(ugeo, vgeo, T * units.degC, 500 * units.hPa,
dx, dy)
def test_first_derivative_scalar_delta():
"""Test first_derivative with a scalar passed for a delta."""
df_dx = first_derivative(np.arange(3), delta=1)
assert_array_almost_equal(df_dx, np.array([1., 1., 1.]), 6)
def test_first_derivative_too_small(deriv_1d_data):
"""Test first_derivative with too small an array."""
with pytest.raises(ValueError):
first_derivative(deriv_1d_data.values[None, :].T, x=deriv_1d_data.x, axis=1)
def test_first_derivative_too_small(deriv_1d_data):
"""Test first_derivative with too small an array."""
with pytest.raises(ValueError):
first_derivative(deriv_1d_data.values[None, :].T, x=deriv_1d_data.x, axis=1)
def test_first_derivative_scalar_delta():
"""Test first_derivative with a scalar passed for a delta."""
df_dx = first_derivative(np.arange(3), delta=1)
assert_array_almost_equal(df_dx, np.array([1., 1., 1.]), 6)