使用極地立體投影'spstere'
,您可以通過使用極地立體投影'spstere'
獲得南極地區。 boundinglat=-60
:
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
m = Basemap(projection='spstere',boundinglat=-60,lon_0=180,resolution='c')
m.drawcoastlines()
plt.show()
![enter image description here](https://i.stack.imgur.com/FHMeS.png)
注意'spstere'
在南極總是居中。
爲了製作一張不以南極爲中心的地圖,您需要使用"stere"
投影。設置"stere"
投影的角落並不重要。
因此,人們可以在'spstere'
投影中使用一個圖並找出一些將包含感興趣區域的點。在這種情況下,
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
m = Basemap(projection='spstere',boundinglat=-50,
lon_0=180+(-100+-30)/2.,resolution='c')
m.drawmeridians(np.arange(0,360,30),labels=[1,1,1,0])
m.drawparallels(np.arange(-90,90,5))
m.drawcoastlines()
xll, yll = m(-150,-70) # <-- find those points by looking at meridians and parallels
xur, yur = m(-30,-55)
m.scatter([xll,xur], [yll, yur], c="crimson")
plt.show()
![enter image description here](https://i.stack.imgur.com/QW1ug.png)
使用這些點,(-150,-70, -30,-55)
,作爲地圖的角落,然後你可以用繪製投影'stere'
的地圖。
m = Basemap(projection='stere',resolution='c',
lat_0=-90, lon_0=(-100+-30)/2., lat_ts=(-90.+-55.)/2.,
llcrnrlon=-150,urcrnrlon=-30,llcrnrlat=-70,urcrnrlat=-55)
![enter image description here](https://i.stack.imgur.com/mEIzh.png)
如果這種啓發式方法是不是願意,你可以通過創建'spstere'
投影的虛擬地圖自動執行此過程,計算從問題(llcrnrlon=-100,urcrnrlon=-30,llcrnrlat=-90,urcrnrlat=-55.0
)矩形的座標,並創建一個新底圖在stere
與他們投影。以下功能取自ActiveState site(作者PG)。
from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
def polar_stere(lon_w, lon_e, lat_s, lat_n, **kwargs):
'''Returns a Basemap object (NPS/SPS) focused in a region.
lon_w, lon_e, lat_s, lat_n -- Graphic limits in geographical coordinates.
W and S directions are negative.
**kwargs -- Aditional arguments for Basemap object.
'''
lon_0 = lon_w + (lon_e - lon_w)/2.
ref = lat_s if abs(lat_s) > abs(lat_n) else lat_n
lat_0 = np.copysign(90., ref)
proj = 'npstere' if lat_0 > 0 else 'spstere'
prj = Basemap(projection=proj, lon_0=lon_0, lat_0=lat_0,
boundinglat=0, resolution='c')
lons = [lon_w, lon_e, lon_w, lon_e, lon_0, lon_0]
lats = [lat_s, lat_s, lat_n, lat_n, lat_s, lat_n]
x, y = prj(lons, lats)
ll_lon, ll_lat = prj(min(x), min(y), inverse=True)
ur_lon, ur_lat = prj(max(x), max(y), inverse=True)
return Basemap(projection='stere', lat_0=lat_0, lon_0=lon_0,
llcrnrlon=ll_lon, llcrnrlat=ll_lat,
urcrnrlon=ur_lon, urcrnrlat=ur_lat, **kwargs)
llcrnrlon=-100
urcrnrlon=-30
llcrnrlat=-90
urcrnrlat=-55.0
m = polar_stere(llcrnrlon, urcrnrlon, llcrnrlat, urcrnrlat)
m.drawmeridians(np.arange(0,360,30),labels=[1,1,1,0])
m.drawparallels(np.arange(-90,90,30),labels=[1,1,1,1])
m.drawcoastlines()
plt.show()
![enter image description here](https://i.stack.imgur.com/Uhgby.png)
這是輝煌的。正是我需要的。感謝您的詳細解答! – jb16006