我需要使用cartopy
生成地图并在其上绘制一些数据(使用networkx
)。我能够做到,但networkx
对象在地图后面。我试图使用zorder
强制图层的顺序,但是...它不起作用:(
我唯一的想法是为cartopy
几何图形添加一些透明度,但它看起来并不好看......(在这个例子中看起来并不那么糟糕,但是对于我的整个数据,它看起来很像可怕)
关于如何强制订单的任何想法?
这是我的代码:
import cartopy.crs as ccrs
from cartopy.io import shapereader as shpreader
import matplotlib.pyplot as plt
import networkx as nx
paises = ['Portugal', 'France', 'Canada', 'Brazil', 'Kazakhstan']
cidades = ['Aveiro', 'Ust-Kamenogorsk', 'Manaus']
links = [('Aveiro', 'Ust-Kamenogorsk'),
('Manaus', 'Ust-Kamenogorsk'),
('Aveiro', 'Manaus')]
position = {'Aveiro': (-8.65, 40.6),
'Manaus': (-60.0, -3.1),
'Ust-Kamenogorsk': (82.6, 49.97)}
# map using cartopy:
shapename = 'admin_0_countries'
countries_shp = shpreader.natural_earth(resolution='110m',
category='cultural', name=shapename)
ax = plt.axes(projection=ccrs.PlateCarree(central_longitude=0.0, globe=None))
ax.set_global()
for country in shpreader.Reader(countries_shp).records():
nome = country.attributes['name_long']
if nome in paises:
i = paises.index(nome)
artist = ax.add_geometries(country.geometry, ccrs.PlateCarree(),
facecolor='yellow',
#alpha=0.5,
zorder=10)
else:
artist = ax.add_geometries(country.geometry, ccrs.PlateCarree(),
facecolor='0.9',
zorder=10)
# add some data over the cartopy map (using networkx):
G = nx.Graph()
G.add_nodes_from(cidades)
G.add_edges_from(links)
nx.draw_networkx_nodes(G, position, node_size=20, nodelist=cidades, zorder=20)
edges=nx.draw_networkx_edges(G, position, edgelist=links, zorder=20)
plt.show()
答案 0 :(得分:4)
发生了什么事情,zorder=20
没有做任何事情;你可以在他们的源代码中看到它被忽略了。 their draw_networkx_edges
code中networkx
做的是:
def draw_networkx_edges(G, pos,
...
edge_collection.set_zorder(1) # edges go behind nodes
...
their draw_networkx_nodes
code中的是:
def draw_networkx_nodes(G, pos,
...
node_collection.set_zorder(2)
...
现在,解决方案很简单:
zorder
中的add_geometries
设置为1
,则节点将位于地图前面,因为它是zorder 2.但边缘仍然在地图后面,因为它是zorder 1。现在真正更好的解决方案是首先获得node_collection和edge_collection:
nodes = nx.draw_networkx_nodes(G, position, node_size=20, nodelist=cidades)
edges = nx.draw_networkx_edges(G, position, edgelist=links)
然后set_zorder
表示节点和边缘:
nodes.set_zorder(20)
edges.set_zorder(20)
答案 1 :(得分:2)