Orthographic vectorfield

In [1]:
import numpy as np
import geoviews as gv
import geoviews.feature as gf
import cartopy.crs as ccrs

gv.extension('matplotlib')
%output fig='svg' size=200

Define data

In [2]:
def sample_data(shape=(20, 30)):
    """
    Returns ``(x, y, u, v, crs)`` of some vector data
    computed mathematically. The returned crs will be a rotated
    pole CRS, meaning that the vectors will be unevenly spaced in
    regular PlateCarree space.

    """
    crs = ccrs.RotatedPole(pole_longitude=177.5, pole_latitude=37.5)

    x = np.linspace(311.9, 391.1, shape[1])
    y = np.linspace(-23.6, 24.8, shape[0])

    x2d, y2d = np.meshgrid(x, y)
    u = 10 * (2 * np.cos(2 * np.deg2rad(x2d) + 3 * np.deg2rad(y2d + 30)) ** 2)
    v = 20 * np.cos(6 * np.deg2rad(x2d))

    return x, y, u, v, crs

xs, ys, U, V, crs = sample_data()
mag = np.sqrt(U**2 + V**2)
angle = (np.pi/2.) - np.arctan2(U/mag, V/mag)
vectorfield = gv.VectorField((xs, ys, angle, mag), crs=crs)

Plot

In [3]:
opts = dict(size_index='Magnitude', show_grid=True, projection=ccrs.Orthographic(-10, 45))
(gf.ocean * gf.coastline * gf.land * vectorfield.options(**opts)).redim.range(Longitude=(-180, 180), Latitude=(-90, 90))
Out[3]:

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