def shading(self, varname, ax=None, t=None, thkth=None,
azimuth=315, altitude=0, **kwargs):
# extract data
x, y, z = self._extract_xyz(varname, t, thkth=thkth)
w = (3*x[0]-x[1])/2
e = (3*x[-1]-x[-2])/2
n = (3*y[0]-y[1])/2
s = (3*y[-1]-y[-2])/2
# convert to rad from the x-axis
azimuth = (90-azimuth)*np.pi / 180.
altitude = altitude*np.pi / 180.
# compute cartesian coords of the illumination direction
x0 = np.cos(azimuth) * np.cos(altitude)
y0 = np.sin(azimuth) * np.cos(altitude)
z0 = np.sin(altitude)
z0 = 0.0 # remove shades from horizontal surfaces
# compute hillshade (dot product of normal and light direction vectors)
dx = x[1] - x[0]
dy = y[1] - y[0]
u, v = np.gradient(z, dx, dy)
shade = (z0 - u*x0 - v*y0) / (1 + u**2 + v**2)**(0.5)
# plot shadows only (white transparency is not possible)
ax = _get_map_axes(ax)
return ax.imshow((shade > 0)*shade,
cmap=kwargs.pop('cmap', default_cmaps.get('shading')),
norm=kwargs.pop('norm', default_norms.get('shading')),
extent=kwargs.pop('extent', (w, e, n, s)),
**kwargs)
def contourf(self, varname, ax=None, t=None, thkth=None, **kwargs):
ax = _get_map_axes(ax)
x, y, z = self._extract_xyz(varname, t, thkth=thkth)
cs = ax.contourf(x[:], y[:], z,
cmap=kwargs.pop('cmap', default_cmaps.get(varname)),
norm=kwargs.pop('norm', default_norms.get(varname)),
**kwargs)
return cs
def quiver(self, varname, ax=None, t=None, thkth=None, **kwargs):
ax = _get_map_axes(ax)
x, y, u, v, c = self._extract_xyuvc(varname, t, thkth=thkth)
scale = kwargs.pop('scale', 100)
u = np.sign(u)*np.log(1+np.abs(u)/scale)
v = np.sign(v)*np.log(1+np.abs(v)/scale)
return ax.quiver(x, y, u, v, c, scale=scale,
cmap=kwargs.pop('cmap', default_cmaps.get(
'c'+varname.lstrip('vel'))),
norm=kwargs.pop('norm', default_norms.get(
'c'+varname.lstrip('vel'))),
**kwargs)
def streamplot(self, varname, ax=None, t=None, thkth=None, **kwargs):
ax = _get_map_axes(ax)
x, y, u, v, c = self._extract_xyuvc(varname, t, thkth=thkth)
return ax.streamplot(x, y, u, v,
density=kwargs.pop('density',
(1.0, 1.0*len(y)/len(x))),
color=kwargs.pop('color', c),
cmap=kwargs.pop('cmap', default_cmaps.get(
'c'+varname.lstrip('vel'))),
norm=kwargs.pop('norm', default_norms.get(
'c'+varname.lstrip('vel'))),
**kwargs)
def imshow(self, varname, ax=None, t=None, thkth=None, **kwargs):
ax = _get_map_axes(ax)
x, y, z = self._extract_xyz(varname, t, thkth=thkth)
w = (3*x[0]-x[1])/2
e = (3*x[-1]-x[-2])/2
n = (3*y[0]-y[1])/2
s = (3*y[-1]-y[-2])/2
im = ax.imshow(z,
cmap=kwargs.pop('cmap', default_cmaps.get(varname)),
norm=kwargs.pop('norm', default_norms.get(varname)),
interpolation=kwargs.pop('interpolation', 'nearest'),
origin=kwargs.pop('origin', 'lower'),
extent=kwargs.pop('extent', (w, e, n, s)),
**kwargs)
return im
def streamplot(self, varname, ax=None, t=None, thkth=None, velth=None,
**kwargs):
ax = _get_map_axes(ax)
x, y, u, v, c = self._extract_xyuvc(varname, t, thkth=thkth)
if velth is not None:
slow = c < velth
u = np.ma.masked_where(slow, u)
v = np.ma.masked_where(slow, v)
u[u.mask] = np.nan # bug in cartopy streamplot?
v[v.mask] = np.nan # bug in cartopy streamplot?
return ax.streamplot(x, y, u, v,
density=kwargs.pop('density',
(1.0, 1.0*len(y)/len(x))),
color=kwargs.pop('color', c),
cmap=kwargs.pop('cmap', default_cmaps.get(
'c'+varname.lstrip('vel'))),
norm=kwargs.pop('norm', default_norms.get(
'c'+varname.lstrip('vel'))),
**kwargs)
