Shapefile gives warning with GSHHS feature #1659
Description
Hi,
shapefile gives me a warning when I save a figure which has GSHHS features in it. Thought I'd ask it here:
MWE:
import matplotlib.pyplot as plt;
import cartopy.crs as ccrs;
import cartopy;
fig = plt.figure();
proj = ccrs.Mercator(central_longitude = 0);
ax = plt.axes(projection = proj);
ax.add_feature(cartopy.feature.GSHHSFeature(levels = (1, 2), linewidth = 2.0));
print("before");
fig.savefig("test.png");
print("after");output:
before
/home/max/.local/lib/python3.8/site-packages/shapefile.py:385: UserWarning: Shapefile shape has invalid polygon: no exterior rings found (must have clockwise orientation); interpreting holes as exteriors.
warnings.warn('Shapefile shape has invalid polygon: no exterior rings found (must have clockwise orientation); interpreting holes as exteriors.')
after
What is the cause of this and how can it be resolved?
OS: Ubuntu 20.04
Cartopy: 0.18.0
pyshp: 2.1.2
Thanks in advance.