python计算两个经纬度之间的距离

# lat lon - > distance
# 计算经纬度之间的距离，单位为公里

EARTH_REDIUS = 6378.137


def rad(d):
    return d * pi / 180.0


def getDistance(lat1, lng1, lat2, lng2):
    radLat1 = rad(lat1)
    radLat2 = rad(lat2)
    a = radLat1 - radLat2
    b = rad(lng1) - rad(lng2)
    s = 2 * math.asin(math.sqrt(math.pow(math.sin(a/2), 2) + math.cos(radLat1) * math.cos(radLat2) * math.pow(math.sin(b/2), 2)))
    s = s * EARTH_REDIUS
    return s