虽然这可能不是您要寻找的确切内容,但您可以将其用作起点:
import numpy as np
import scipy.optimize as opt
def calc_distance(point):
return np.power(np.sum(np.power(centers-point,2),axis=1),.5)-rad
def geo2cart(lat,lon):
lat=np.deg2rad(lat)
lon=np.deg2rad(lon)
points=np.vstack((earth_radius*np.cos(lat)*np.cos(lon),
earth_radius*np.cos(lat)*np.sin(lon),
earth_radius*np.sin(lat))).T
return points
def cart2geo(xyz):
if xyz.ndim==1: xyz=xyz[None,:]
lat=np.arcsin(xyz[:,2]/earth_radius)
lon=np.arctan2(xyz[:,1],xyz[:,0])
return np.rad2deg(lat),np.rad2deg(lon)
def minimize(point):
dist= calc_distance(point)
err=np.linalg.norm(dist/rad)
return err
earth_radius = 6378
p1 = (31.2297, 121.4734, 3335.65)
p2 = (34.539, 69.171, 2477.17)
p3 = (47.907, 106.91, 1719.65)
p4 = (50.43, 80.25, 1242.27)
points = np.vstack((p1,p2,p3,p4))
lat = points[:,0]
lon = points[:,1]
rad = points[:,2]
centers = geo2cart(lat,lon)
out=[]
for x in range(30):
latrand=np.average(lat/rad)*np.random.rand(1)*np.sum(rad)
lonrand=np.average(lon/rad)*np.random.rand(1)*np.sum(rad)
start=geo2cart(latrand,lonrand)
end_pos=opt.fmin_powell(minimize,start)
out.append([cart2geo(end_pos),np.linalg.norm(end_pos-geo2cart(36.989,91464))])
out = sorted(out, key=lambda x: x[1])
print 'Latitude:',out[0][0][0],'Longitude:',out[0][0][1],'Distance:',out[0][1]
我们得到:
First set of points: lat 40.1105092 lon 88.07068701
Second set of points: lat 40.36636421 lon 88.84527729
我相信有更好的方式,但至少你可以通过调整权重和误差函数来看看会发生什么。当然存在几个严重问题之一是可能会陷入局部最优。可能有一种最小二乘方法来解决这个问题-只是我目前没有看到。
为了双重检查,这是否可行:
p0=np.random.rand(2)*90+20
p1=np.random.rand(2)*-10+20+p0
p2=np.random.rand(2)*-10+20+p0
p3=np.random.rand(2)*-10+20+p0
p4=np.random.rand(2)*-10+20+p0
target=geo2cart(p0[0],p0[1])
points=np.vstack((p1,p2,p3,p4))
lat = points[:,0]
lon = points[:,1]
centers=geo2cart(lat,lon)
rad = np.power(np.sum(np.power(centers-target,2),axis=1),.5)
print '------------'
start=geo2cart(np.average(lat),np.average(lon))
end_pos=opt.fmin_powell(minimize,start)
print 'Exact',p0
print 'Start guess',cart2geo(start)
print 'Found',cart2geo(end_pos)
print 'Distance',np.linalg.norm(end_pos-target)
Exact [ 45.21292244 101.85151772]
Start guess (array([ 60.63554123]), array([ 115.08426225]))
Found (array([ 45.21292244]), array([ 101.85151772]))
Distance 5.30420680512e-11