Python Basemap drawgreatcircle函数

Question

嗨,我正在尝试使用Basemap(matplot lib的一部分)中的greatcircle函数将ip地址图绘制到世界地图上,但每次我连接跨越太平洋的两个点(即美国西海岸的某个地方,澳大利亚)我的情节中出现了一条水平线.

我知道这是因为这个问题:

Note Cannot handle situations in which the great circle intersects the edge of the map projection domain, and then re-enters the domain. (http://matplotlib.org/basemap/api/basemap_api.html#mpl_toolkits.basemap.Basemap.drawgreatcircle)

只是想知道是否有人知道如何解决它或知道另一个包没有"有这个问题.谢谢!

Answer 1

要在特定情况下在Basemap中解决此问题,您可以检查生成的路径中x顶点的差异.从那里,我们可以将坏道路分为两部分.我把自己用底图做的这个例子放在一起:

from mpl_toolkits.basemap import Basemap
import numpy as np
import matplotlib.pyplot as plt


m = Basemap(projection='cyl', lon_0=0, resolution='c')

m.fillcontinents(color='coral',lake_color='aqua')
m.drawmapboundary(fill_color='aqua')

places = {'Mexico City': (19.05, -99.366667),
          'London': (51.507222, -0.1275),
          'Sydney': (-33.859972, 151.211111),
          'Cape Town': (-33.925278, 18.423889),
          'Delhi': (28.61, 77.23),
          }

network = [
           ('London', 'Delhi'),
           ('Mexico City', 'Sydney'),
           ]


for source, target in network:
    lat1, lon1 = places[source]
    lat2, lon2 = places[target]
    line, = m.drawgreatcircle(lon1, lat1, lon2, lat2, lw=3)

    p = line.get_path()
    # find the index which crosses the dateline (the delta is large)
    cut_point = np.where(np.abs(np.diff(p.vertices[:, 0])) > 200)[0]
    if cut_point:
        cut_point = cut_point[0]

        # create new vertices with a nan inbetween and set those as the path's vertices
        new_verts = np.concatenate(
                                   [p.vertices[:cut_point, :], 
                                    [[np.nan, np.nan]], 
                                    p.vertices[cut_point+1:, :]]
                                   )
        p.codes = None
        p.vertices = new_verts


plt.show()

结果:

这不是一般解决方案,只有在你拥有纬度和经度时才有效.解决一般问题要困难得多,并且是纸板的重点(http://scitools.org.uk/cartopy/docs/latest/).我将在接下来的几天里发布一个在cartopy中完全相同的情节的例子.

HTH