用底图绘制小河

Question

我正在尝试使用Python中的底图模块显示特拉华河。但是，我能得到的最接近的是延伸至特拉华湾的河的下部。我尝试过

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

m = Basemap(width=120000,height=90000,projection='stere',resolution='f',lat_1=39.82,lat_2=39.88,lat_0=39.86,lon_0=-75.23694)
m.drawcoastlines()
m.drawrivers()
plt.show()

但这仅提供河流的下部和部分河流的中心线。从底图可以找到特拉华河大部分地区的详细地图，还是需要导入河流的shapefile？

Answer 1

当您需要地图上的特定数据功能而地图的数据库不提供它们时，您需要从某个地方获取它们并投入使用。在这里，我从GG My Maps上绘制得到了数据（long，lat）。一旦在地图上绘制了一条沿河流路径的线，就可以将线数据导出为KML。从该KML文件中，我仅获取（long，lat，h）的列表，并进行一些编辑以在以下代码中获取lons和lats的数据。

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

lons = np.array([-74.8739737, -74.8633163, -74.8585042, -74.8564394, -74.8524035,
       -74.8459655, -74.830347 , -74.7874564, -74.7661703, -74.7593039,
       -74.7531241, -74.7345847, -74.7235983, -74.724285 , -74.7380179,
       -74.7469443, -74.7641104, -74.7826498, -74.8005026, -74.8142355,
       -74.8259085, -74.832775 , -74.8355215, -74.852001 , -74.8623007,
       -74.8698538, -74.9014395, -74.9158591, -74.9302786, -74.9453848,
       -74.9701041, -74.9982565, -75.0140494, -75.0270956, -75.047695 ,
       -75.0552481, -75.0655478, -75.0731009, -75.0916403, -75.111553 ,
       -75.1294058, -75.1369589, -75.1383322, -75.1300925, -75.1300925,
       -75.1355856, -75.1403921, -75.1695615, -75.1971884, -75.2130589,
       -75.2385357, -75.2697054, -75.3127467, -75.3521119, -75.3813978,
       -75.3987804, -75.4230237, -75.4458246])

lats = np.array([40.3023524, 40.2900427, 40.2829709, 40.2758991, 40.2654202,
       40.2567749, 40.2447233, 40.2248056, 40.2127464, 40.1959649,
       40.1828514, 40.1739328, 40.1597655, 40.1471699, 40.1392965,
       40.1356219, 40.134047 , 40.1219717, 40.1219717, 40.1282721,
       40.1277471, 40.1203965, 40.0988651, 40.0941378, 40.0878342,
       40.0825808, 40.0725981, 40.0704963, 40.0715472, 40.062614 ,
       40.050526 , 40.0310756, 40.0221371, 40.0179303, 40.0079382,
       40.0005746, 39.9884756, 39.9795315, 39.9742697, 39.9711125,
       39.9616398, 39.9542712, 39.9321608, 39.9179432, 39.9031959,
       39.8937139, 39.8847574, 39.8809411, 39.8785011, 39.8662113,
       39.8560259, 39.8505758, 39.8494219, 39.8388161, 39.8197959,
       39.8092274, 39.8007649, 39.7931383])

fig = plt.figure(figsize=[8,8])
ax = plt.gca()

m = Basemap(width=120000, height=90000, projection='stere', resolution='f', \
            lat_1=39.82, lat_2=39.88, lat_0=39.86, lon_0=-75.23694)

m.drawcoastlines()
# m.drawrivers()  # no needed now

# plot Delaware river using arrays of data
m.plot( *m(lons, lats), linewidth=2.5, color='blue', zorder=18)
plt.show()

结果图：