def test_speed():
# run speed in xroms
xvar = xroms.speed(ds.u, ds.v, grid)
# calculate own version of speed
var = np.sqrt(u ** 2 + v ** 2)
# these aren't identical because of grid shifting
assert np.allclose(xvar.mean(), var.mean(), rtol=1e-2)
def test_speed():
acc = ds.xroms.speed
assert np.allclose(acc, xroms.speed(ds.u, ds.v, grid))
# also check attributes
acc.name == acc.attrs["name"]
acc.attrs["grid"] == ds.xroms.grid
# cf-xarray: make sure all Axes and Coordinates available in output
items = ["T", "X", "Y", "Z", "longitude", "latitude", "vertical", "time"]
assert set(items).issubset(acc.cf.get_valid_keys())
def test_KE():
rho = xroms.density(temp, salt, z_rho)[:, np.newaxis, np.newaxis]
s2 = (u ** 2 + v ** 2)[np.newaxis, :, :]
KE = 0.5 * rho * s2
# xroms
s = xroms.speed(ds.u, ds.v, grid)
assert np.allclose(
xroms.to_grid(xroms.KE(ds.rho0, s), grid, hcoord="psi").mean(),
KE.mean(),
rtol=1e-2,
)
def speed(self):
"""Calculate horizontal speed [m/s] from u and v components, on rho/rho grids.
Notes
-----
speed = np.sqrt(u^2 + v^2)
Uses 'extend' for horizontal boundary.
See `xroms.speed` for full docstring.
Example usage
-------------
>>> ds.xroms.speed
"""
if "speed" not in self.ds:
var = xroms.speed(self.ds.u,
self.ds.v,
self.grid,
hboundary="extend")
self.ds["speed"] = var
return self.ds.speed