Problems with pcolormesh in Cartopy

Question

I'm trying to adapt the Cartopy example plot for circular South Polar Stereographic plots to the North Pole and add data to it. I have a couple questions.

First, in the example code, the land feature is added before the ocean feature. When I did that, I got a map with only ocean. I reversed the order of the call in the code below and get a map with land and ocean. Why did the other order work with the South Polar example?

Second, and more importantly, I can't figure out why my pcolormesh call isn't having any effect.

I'm using Python 2.7.7, matplotlib 1.5.1, and Cartopy 0.15.1.

import matplotlib.path as mpath
import matplotlib.pyplot as plt
import numpy as np

import cartopy.crs as ccrs
import cartopy.feature

lats = np.linspace(60,90,30)
lons = np.linspace(0,360,200)
X,Y = np.meshgrid(lons,lats)
Z = np.random.normal(size = X.shape)

def main():
    fig = plt.figure(figsize=[10, 5])
    ax = plt.subplot(1, 1, 1, projection=ccrs.NorthPolarStereo())
    fig.subplots_adjust(bottom=0.05, top=0.95,
                        left=0.04, right=0.95, wspace=0.02)

    # Limit the map to -60 degrees latitude and below.
    ax.set_extent([-180, 180, 60, 60], ccrs.PlateCarree())

    ax.gridlines()

    ax.add_feature(cartopy.feature.OCEAN)
    ax.add_feature(cartopy.feature.LAND)

    # Compute a circle in axes coordinates, which we can use as a boundary
    # for the map. We can pan/zoom as much as we like - the boundary will be
    # permanently circular.
    theta = np.linspace(0, 2*np.pi, 100)
    center, radius = [0.5, 0.5], 0.5
    verts = np.vstack([np.sin(theta), np.cos(theta)]).T
    circle = mpath.Path(verts * radius + center)

    ax.set_boundary(circle, transform=ax.transAxes)
    ax.pcolormesh(X,Y,Z,transform=ccrs.PlateCarree())


    plt.show()


if __name__ == '__main__':
    main()

Problems with pcolormesh in Cartopy

1 Answers