python根据地球经纬度计算距离

#coding=utf-8

from math import *

# input Lat_A 纬度A
# input Lng_A 经度A
# input Lat_B 纬度B
# input Lng_B 经度B
# output distance 距离(km)
def calcDistance(Lat_A, Lng_A, Lat_B, Lng_B):
ra = 6378.140  # 赤道半径 (km)
rb = 6356.755  # 极半径 (km)
flatten = (ra - rb) / ra  # 地球扁率
rad_lat_A = radians(Lat_A)
rad_lng_A = radians(Lng_A)
rad_lat_B = radians(Lat_B)
rad_lng_B = radians(Lng_B)
pA = atan(rb / ra * tan(rad_lat_A))
pB = atan(rb / ra * tan(rad_lat_B))
xx = acos(sin(pA) * sin(pB) + cos(pA) * cos(pB) * cos(rad_lng_A - rad_lng_B))
c1 = (sin(xx) - xx) * (sin(pA) + sin(pB)) ** 2 / cos(xx / 2) ** 2
c2 = (sin(xx) + xx) * (sin(pA) - sin(pB)) ** 2 / sin(xx / 2) ** 2
dr = flatten / 8 * (c1 - c2)
distance = ra * (xx + dr)
return distance

Lat_A=32.060255; Lng_A=118.796877 # 南京
Lat_B=39.904211; Lng_B=116.407395 # 北京
distance=calcDistance(Lat_A,Lng_A,Lat_B,Lng_B)
print('(Lat_A, Lng_A)=({0:10.3f},{1:10.3f})'.format(Lat_A,Lng_A))
print('(Lat_B, Lng_B)=({0:10.3f},{1:10.3f})'.format(Lat_B,Lng_B))
print('Distance={0:10.3f} km'.format(distance))