我正在使用以下代码制作一张瑞典、挪威和芬兰作为一个区域的地图。然而，我正在为此挣扎。我正在关注这个示例，Python Mapping in Matplotlib Cartopy Color One Country。
from shapely.geometry import Polygon
from cartopy.io import shapereader
import cartopy.io.img_tiles as cimgt
import cartopy.crs as ccrs
import geopandas
import matplotlib.pyplot as plt
def rect_from_bound(xmin, xmax, ymin, ymax):
"""Returns list of (x,y)'s for a rectangle"""
xs = [xmax, xmin, xmin, xmax, xmax]
ys = [ymax, ymax, ymin, ymin, ymax]
return [(x, y) for x, y in zip(xs, ys)]
# request data for use by geopandas
resolution = '10m'
category = 'cultural'
name = 'admin_0_countries'
countries = ['Norway', 'Sweden', 'Finland']
shpfilename = shapereader.natural_earth(resolution, category, name)
df = geopandas.read_file(shpfilename)
extent = [2, 32, 55, 72]
# get geometry of a country
for country in (countries):
poly = [df.loc[df['ADMIN'] == country]['geometry'].values[0]]
stamen_terrain = cimgt.StamenTerrain()
# projections that involved
st_proj = stamen_terrain.crs #projection used by Stamen images
ll_proj = ccrs.PlateCarree() #CRS for raw long/lat
# create fig and axes using intended projection
fig = plt.figure(figsize=(8,9))
ax = fig.add_subplot(122, projection=st_proj)
ax.add_geometries(poly, crs=ll_proj, facecolor='none', edgecolor='black')
pad1 = 0.5 #padding, degrees unit
exts = [poly[0].bounds[0] - pad1, poly[0].bounds[2] + pad1, poly[0].bounds[1] - pad1, poly[0].bounds[3] + pad1];
ax.set_extent(exts, crs=ll_proj)
# make a mask polygon by polygon's difference operation
# base polygon is a rectangle, another polygon is simplified switzerland
msk = Polygon(rect_from_bound(*exts)).difference( poly[0].simplify(0.01) )
msk_stm = st_proj.project_geometry (msk, ll_proj) # project geometry to the projection used by stamen
# get and plot Stamen images
ax.add_image(stamen_terrain, 8) # this requests image, and plot
# plot the mask using semi-transparency (alpha=0.65) on the masked-out portion
ax.add_geometries( msk_stm, st_proj, zorder=12, facecolor='white', edgecolor='none', alpha=0.65)
ax.gridlines(draw_labels=True)
plt.show()
What I have is separated maps. THoguh I need only one map of them.
Can you please help?
Thank you.
代码here你适应你的工作对一个国家来说是有好处的。如果多个连续的国家是新目标，则需要选择所有这些国家并分解为一个几何体。只需要修改几行代码。
示例：新目标国家/地区：['挪威'、'瑞典'、'芬兰']
需要替换的代码行：
poly = [df.loc[df['ADMIN'] == 'Switzerland']['geometry'].values[0]]
将其替换为以下代码行：
scan3 = df[ df['ADMIN'].isin(['Norway','Sweden', 'Finland']) ]
scan3_dissolved = scan3.dissolve(by='LEVEL')
poly = [scan3_dissolved['geometry'].values[0]]
你应该得到类似这样的情节：
