import hvplot.xarray # noqa import numpy as np import xarray as xr import geoviews as gv import cartopy.crs as ccrs def sample_data(shape=(20, 30)): """ Return ``(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) ds = xr.Dataset({'mag': xr.DataArray(mag, dims=('y', 'x'), coords={'y': ys, 'x': xs}), 'angle': xr.DataArray(angle, dims=('y', 'x'), coords={'y': ys, 'x': xs})}, attrs={'crs': crs}) ds ds.hvplot.vectorfield(x='x', y='y', angle='angle', mag='mag', hover=False).opts(magnitude='mag') ds.hvplot.vectorfield(x='x', y='y', angle='angle', mag='mag', hover=False, geo=True).opts(magnitude='mag') * gv.tile_sources.CartoLight