设置边界后如何添加刻度标签？

Question

我尝试使用.set_boundary（）之后添加刻度标签，但失败了。如何实现？

ax1.set_extent([-180, 180, -90, -60], ccrs.PlateCarree())
ax1.add_feature(cfeature.LAND)
ax1.add_feature(cfeature.OCEAN)
ax1.gridlines()

ax2.gridlines()
ax2.add_feature(cfeature.LAND)
ax2.add_feature(cfeature.OCEAN)
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)
ax2.set_boundary(circle, transform=ax2.transAxes)

ax1.gridlines(draw_labels=True)
ax2.gridlines(draw_labels=True)

enter image description here

Answer 1

您的示例中缺少代码，因此我不确定它是否可以解决您的问题，但是Cartopy允许对仅以0.18版（whats new和PR开始的所有投影进行经度和纬度标签）。在此之前，仅允许使用PlateCarree和Mercator，其他任何投影都将因错误而失败：

TypeError: Cannot label gridlines on a SouthPolarStereo plot. Only PlateCarree and Mercator plots are currently supported.

使用v0.18的代码（我从上面链接的PR中获得）使lonlat标签变得很好：

import numpy as np
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature

projection = ccrs.SouthPolarStereo()
extent = [-180, 180, -90, -60]

fig = plt.figure(figsize=(6, 6))
ax = fig.add_subplot(1, 1, 1, projection=projection)
ax.set_extent(extent, crs=ccrs.PlateCarree())
ax.coastlines(resolution='50m', color='k')
ax.gridlines(color='lightgrey', linestyle='-', draw_labels=True)