Cartopy set_extent()错误

Question

我试图绘制地图上某一区域的等高线图，我可以毫无问题地在地图上创建等高线，但是当我将范围设置为下面的范围时，不管有没有等高线图，我都会得到下面的错误(Cartopy版本0.20.3)：

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


p = ccrs.Mercator()
ax = plt.axes(projection=p)
ax.set_extent([-140, -60, 20, 70], crs=ccrs.Mercator())
ax.coastlines()
ax.gridlines()
plt.show()

TypeError                                 Traceback (most recent call last) Input In [5], in <cell line: 7>()
      5 p = ccrs.Mercator()
      6 ax = plt.axes(projection=p)
----> 7 ax.set_extent([-140, -60, 20, 70], crs=ccrs.Mercator())
      8 ax.coastlines()
      9 ax.gridlines()
File ~\Anaconda3\envs\geospatial\lib\site-packages\cartopy\mpl\geoaxes.py:904,
in GeoAxes.set_extent(self, extents, crs)
    901         projected = boundary

    903 if projected is None:
--> 904     projected = self.projection.project_geometry(domain_in_crs, crs)
    905 try:
    906     # This might fail with an unhelpful error message ('need more
    907     # than 0 values to unpack') if the specified extents fall outside
    908     # the projection extents, so try and give a better error message.
    909     x1, y1, x2, y2 = projected.bounds

File ~\Anaconda3\envs\geospatial\lib\site-packages\cartopy\crs.py:805, in Projection.project_geometry(self, geometry, src_crs)
    803 if not method_name:
    804     raise ValueError(f'Unsupported geometry type {geom_type!r}')
--> 805 return getattr(self, method_name)(geometry, src_crs)

File ~\Anaconda3\envs\geospatial\lib\site-packages\cartopy\crs.py:811, in Projection._project_line_string(self, geometry, src_crs)
    810 def _project_line_string(self, geometry, src_crs):
--> 811     return cartopy.trace.project_linear(geometry, src_crs, self)

File lib/cartopy/trace.pyx:628, in cartopy.trace.project_linear()

File lib/cartopy/trace.pyx:100, in cartopy.trace.geos_from_shapely()

TypeError: an integer is required

Answer 1

变化

ax.set_extent([-140, -60, 20, 70], crs=ccrs.Mercator()) 

(因为值和crs不匹配)

至

ax.set_extent([-140, -60, 20, 70], crs=ccrs.PlateCarree())