# Make an EllipseCollection.
ellipses = EllipseCollection(widths, heights, rotations,
offsets=xy,
units='xy',
transOffset=ax.transData)
ellipses.set_array(np.asarray(sema))
# Add coastlines
m.drawmapboundary(zorder=0)
m.drawcoastlines(zorder=1)
m.fillcontinents(zorder=0, color='0.6')
m.drawparallels(parallels, labels=[1, 0, 0, 0], linewidth=0)
m.drawmeridians(meridians, labels=[0, 0, 0, 1], linewidth=0)
# Add ellipses coloured by the semi-major axis magnitude.
ax.add_collection(ellipses)
ellipses.set_linewidth(0)
ellipses.set_cmap(cm.viridis)
ellipses.set_zorder=200
# Add a nice colour bar.
div = make_axes_locatable(ax)
cax = div.append_axes("right", size="5%", pad=0.2)
cb = fig.colorbar(ellipses, cax=cax)
cb.set_label("Semi-major axis ($ms^{-1}$)")
ax.set_title('$M_2$ tidal ellipses')
