package main
import (
"fmt"
"math"
)
// 球面距离公式:https://baike.baidu.com/item/%E7%90%83%E9%9D%A2%E8%B7%9D%E7%A6%BB%E5%85%AC%E5%BC%8F/5374455?fr=aladdin
// GeoDistance 计算地理距离,依次为两个坐标的纬度、经度、单位(默认:英里,K => 公里,N => 海里)
func GeoDistance(lng1 float64, lat1 float64, lng2 float64, lat2 float64, unit ...string) float64 {
const PI float64 = 3.141592653589793
radlat1 := float64(PI * lat1 / 180)
radlat2 := float64(PI * lat2 / 180)
theta := float64(lng1 - lng2)
radtheta := float64(PI * theta / 180)
dist := math.Sin(radlat1)*math.Sin(radlat2) + math.Cos(radlat1)*math.Cos(radlat2)*math.Cos(radtheta)
if dist > 1 {
dist = 1
}
dist = math.Acos(dist)
dist = dist * 180 / PI
dist = dist * 60 * 1.1515
if len(unit) > 0 {
if unit[0] == "K" {
dist = dist * 1.609344
} else if unit[0] == "N" {
dist = dist * 0.8684
}
}
return dist
}
func main() {
fmt.Printf("%f 公里", GeoDistance(120.090564, 30.344981, 120.11638, 30.2959, "K"))
}