Source code for Meteorographica.wind.plot

# (C) British Crown Copyright 2017, Met Office
# This code is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This code is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU Lesser General Public License for more details.

import iris
import matplotlib
import numpy

import Meteorographica.utils as utils
from .wind_vectors import *

[docs]def plot_quiver(ax,ue,ve,**kwargs): """Plots a pair of variables as a 2d field of arrows. This is the same as :meth:`matplotlib.axes.Axes.quiver`, except that it takes :class:`iris.cube.Cube` as arguments instead of a set of vectors, and its defaults are chosen for plots of 10m wind. *WARNING* This function is under development - in particular the argument names are badly chosen and will need to be changed. Args: ax (:obj:`cartopy.mpl.geoaxes.GeoAxes`): Axes on which to draw. ue (:obj:`iris.cube.Cube`): meridional value of variable to plot. ve (:obj:`iris.cube.Cube`): zonal value of variable to plot. Keyword Args: resolution (:obj:`float`): What lat:lon resolution (in degrees) to interpolate [uv] to before plotting. Defaults to 1 degree. colors (see :mod:`matplotlib.colors`) vector colour. Defaults to (0,0,0,0.25). headwidth (:obj:`float`): Controls arrow shape. Defaults to 1. random_state (None|:obj:`int`|:obj:`numpy.random.RandomState`): Random number generation seed, see :func:`sklearn.utils.check_random_state`. max_points (:obj:`int`): Maximum number of vectors to allocate, defaults to 100,000. zorder (:obj:`float`): Standard matplotlib parameter determining which things are plotted on top (high zorder), and which underneath (low zorder), Defaults to 50. Returns: See :meth:`matplotlib.axes.Axes.quiver` - also adds the vectors to the plot. | """ kwargs.setdefault('points' ,None) kwargs.setdefault('scale' ,None) kwargs.setdefault('resolution' ,1) kwargs.setdefault('color' ,(0,0,0,0.25)) kwargs.setdefault('headwidth' ,1) kwargs.setdefault('random_state',None) kwargs.setdefault('max_points' ,100000) kwargs.setdefault('zorder' ,50) pole_latitude=ax.projection.proj4_params['o_lat_p'] pole_longitude=ax.projection.proj4_params['lon_0']-180 projection_iris=iris.coord_systems.RotatedGeogCS(pole_latitude, pole_longitude) rw=iris.analysis.cartography.rotate_winds(ue,ve,projection_iris) plot_cube=utils.dummy_cube(ax,kwargs.get('resolution')) u_p = rw[0].regrid(plot_cube,iris.analysis.Linear()) v_p = rw[1].regrid(plot_cube,iris.analysis.Linear()) if kwargs.get('points') is None: if kwargs.get('scale') is None: kwargs['scale']=kwargs.get('resolution') points=allocate_vector_points(initial_points=None, lat_range=(min(u_p.coord('latitude').points), max(u_p.coord('latitude').points)), lon_range=(min(u_p.coord('longitude').points), max(u_p.coord('longitude').points)), scale=kwargs.get('scale'), random_state=kwargs.get('random_state'), max_points=kwargs.get('max_points')) lats = points['Latitude'] lons = points['Longitude'] u_interpolator = iris.analysis.Linear().interpolator(u_p, ['latitude', 'longitude']) v_interpolator = iris.analysis.Linear().interpolator(v_p, ['latitude', 'longitude']) u_i=numpy.zeros(lons.size) v_i=numpy.zeros(lons.size) for i in range(lons.size): u_i[i]=u_interpolator([lats[i],lons[i]]).data*-1 v_i[i]=v_interpolator([lats[i],lons[i]]).data*-1 qv=ax.quiver(lons,lats,u_i,v_i, headwidth=kwargs.get('headwidth'), color=kwargs.get('color'), scale=2000, zorder=kwargs.get('zorder')) return qv
# Plot wind
[docs]def plot(ax,ue,ve,**kwargs): """Plot precipitation. Generic function for plotting wind. Use the 'type' argument to choose the plot style. Args: ax (:obj:`cartopy.mpl.geoaxes.GeoAxes`): Axes on which to draw. ue (:obj:`iris.cube.Cube`): Zonal wind to plot - must be 2d, with dimensions latitude and longitude. ve (:obj:`iris.cube.Cube`): Meridional wind to plot - must be 2d, with dimensions latitude and longitude. Kwargs: type (:obj:`str`, optional): Style to plot. Default is 'quiver', which delegates plotting to :meth:`plot_quiver` and at the moment this is the only choice. Other keyword arguments are passed to the style-specific plotting function. | """ kwargs.setdefault('type','quiver') if kwargs.get('type')=='quiver': return plot_quiver(ax,ue,ve,**kwargs) raise Exception('Unsupported wind plot type %s' % kwargs.get('type'))