Rotated pole mapping

This example uses several visualisation methods to achieve an array of differing images, including:

• Visualisation of point based data
• Contouring of point based data
• Block plot of contiguous bounded data
• Non native projection and a Natural Earth shaded relief image underlay

"""
Rotated pole mapping
=====================

This example uses several visualisation methods to achieve an array of
differing images, including:

 * Visualisation of point based data
 * Contouring of point based data
 * Block plot of contiguous bounded data
 * Non native projection and a Natural Earth shaded relief image underlay

"""
import cartopy.crs as ccrs
import matplotlib.pyplot as plt

import iris
import iris.plot as iplt
import iris.quickplot as qplt
import iris.analysis.cartography


def main():
    # Enable a future option, to ensure that the netcdf load works the same way
    # as in future Iris versions.
    iris.FUTURE.netcdf_promote = True

    # Load some test data.
    fname = iris.sample_data_path('rotated_pole.nc')
    air_pressure = iris.load_cube(fname)

    # Plot #1: Point plot showing data values & a colorbar
    plt.figure()
    points = qplt.points(air_pressure, c=air_pressure.data)
    cb = plt.colorbar(points, orientation='horizontal')
    cb.set_label(air_pressure.units)
    plt.gca().coastlines()
    iplt.show()

    # Plot #2: Contourf of the point based data
    plt.figure()
    qplt.contourf(air_pressure, 15)
    plt.gca().coastlines()
    iplt.show()

    # Plot #3: Contourf overlayed by coloured point data
    plt.figure()
    qplt.contourf(air_pressure)
    iplt.points(air_pressure, c=air_pressure.data)
    plt.gca().coastlines()
    iplt.show()

    # For the purposes of this example, add some bounds to the latitude
    # and longitude
    air_pressure.coord('grid_latitude').guess_bounds()
    air_pressure.coord('grid_longitude').guess_bounds()

    # Plot #4: Block plot
    plt.figure()
    plt.axes(projection=ccrs.PlateCarree())
    iplt.pcolormesh(air_pressure)
    plt.gca().stock_img()
    plt.gca().coastlines()
    iplt.show()


if __name__ == '__main__':
    main()

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