在 cartopy 地图上绘制 shapefile 城市边界

Question

我正在尝试使用获得的 shapefile here and following this example 在 cartopy 地形图的顶部绘制湾区 city/town 边界的轮廓。出于某种原因，即使我通过 zorder 指定边框位于顶部，边框也不会显示。我错过了什么吗？

# import functions
import matplotlib.pyplot as plt
import cartopy.io.img_tiles as cimgt
import cartopy.crs as ccrs
from cartopy.io.shapereader import Reader
from cartopy.feature import ShapelyFeature

# Create a Stamen terrain background instance
stamen_terrain = cimgt.Stamen('terrain-background')
fig = plt.figure(figsize = (10, 10))
ax = fig.add_subplot(1, 1, 1, projection=stamen_terrain.crs)

# Set range of map, stipulate zoom level
ax.set_extent([-122.7, -121.5, 37.15, 38.15], crs=ccrs.Geodetic())
ax.add_image(stamen_terrain, 12, zorder = 0)

# Add city borders - not working
filename = r'./shapefile/ba_cities.shp' # from https://earthworks.stanford.edu/catalog/stanford-vj593xs7263
shape_feature = ShapelyFeature(Reader(filename).geometries(), ccrs.PlateCarree(), edgecolor='black')
ax.add_feature(shape_feature, zorder = 1)
plt.show()

Answer 1

正如@ImportanceOfBeingErnest 和@swatchai 建议的那样，ShapelyFeature cartopy.feature.ShapelyFeature() 中的 CRS（坐标参考系统）参数不正确。

可以在 shapefile 附带的 .xml 文件之一中找到正确的 EPSG（欧洲石油调查组？）代码：

   <gco:CharacterString>26910</gco:CharacterString>
</code>
<codeSpace>
   <gco:CharacterString>EPSG</gco:CharacterString>

并将其作为第二个参数传递到 ShapelyFeature() 中就可以让 shapefile 正确绘制城市边界：

# Add city borders
filename = r'./shapefile/ba_cities.shp'
shape_feature = ShapelyFeature(Reader(filename).geometries(), ccrs.epsg(26910), 
                               linewidth = 1, facecolor = (1, 1, 1, 0), 
                               edgecolor = (0.5, 0.5, 0.5, 1))
ax.add_feature(shape_feature)
plt.show()

在 cartopy 地图上绘制 shapefile 城市边界

Plot shapefile city borders on top of cartopy map

python

matplotlib

shapefile

cartopy