Python elegantly calculates geospatial distances using two points of latitude and longitude

Overview of main contents ：

One 、 The basic principle of calculating distance according to longitude and latitude

When processing geographic data , It is often necessary to use the distance between two geographical locations . With a little （ Longitude value , Latitude value ） The longitude and latitude coordinates of the place , such as A Point latitude and longitude （30.553949,114.357399）,B Point latitude and longitude （129.1344,25.5465）, seek AB The distance between two points .

We know that any two points on the earth （lng1,lat1）,（lng2, lat2） The latitude and longitude coordinates of , To find the distance between two points, you can use haversine The formula ：

• First , Turn the angle of longitude and latitude coordinates into radians （rlng1,rlat1）,（rlng2,rlat2)
• then , Use the following formula to calculate ：

among , a Express The difference between two latitudes , namely a = rlat1 - rlat2; b Express The difference in longitude between two points , namely b = rlng1 - rlng2, among r Represents the radius of the earth .

Take the distance between Tsinghua University and Peking University as an example , Use Baidu map （  website ： Baidu Maps ） Distance measurement , The distance between Tsinghua University and Peking University is about 1.8km, As shown below ：

Two 、 Get the latitude and longitude of the location

Geocoding with Gaud maps / Reverse geocoding API , To get the longitude and latitude of Peking University and Tsinghua University ,Python The code implementation is as follows ：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import requests
KEY = ' Access code of your Gaud map application '
def geocode(address):
"""
According to the place name , Get latitude and longitude
"""
parameters = {'address': address, 'key': KEY}
base = 'http://restapi.amap.com/v3/geocode/geo'
response = requests.get(base, parameters)
answer = response.json()
# print(answer)
# print(type(answer))
print(address + " Longitude and latitude of ：", answer['geocodes'][0]['location'])
if __name__ == "__main__":
address1 = ' Peking University, '
lon_lat1 = geocode(address1)
address2 = ' Tsinghua University '
lon_lat2 = geocode(address2)

  among ,KEY Apply for the authorized access code of Gaode map application for yourself . Just enter the address parameter , You can print out the longitude and latitude coordinates of the corresponding address .

The running result is ：

 The longitude and latitude of Peking University ： 116.308264,39.995304
The longitude and latitude of Tsinghua University ： 116.326759,40.003304

3、 ... and 、 Handwriting haversine Formula calculation

according to  haversine The formula , Custom implementation python Version calculation formula , as follows ：

from math import sin, asin, cos, radians, fabs, sqrt
EARTH_RADIUS = 6371.137 # The average radius of the earth is about 6371km
def hav(theta):
s = sin(theta / 2)
return s * s
def get_distance_hav(lat0, lng0, lat1, lng1):
# use haversine The formula calculates the distance between two points on the sphere
# Conversion of longitude and latitude to radian
lat0 = radians(lat0)
lat1 = radians(lat1)
lng0 = radians(lng0)
lng1 = radians(lng1)
dlng = fabs(lng0 - lng1)
dlat = fabs(lat0 - lat1)
h = hav(dlat) + cos(lat0) * cos(lat1) * hav(dlng)
distance = 2 * EARTH_RADIUS * asin(sqrt(h)) # km
return distance
if __name__ == "__main__":
result = get_distance_hav(39.995304, 116.308264, 40.003304, 116.326759)
print(" distance ：{:.3}km".format(result))

The running result is ：

 distance ：1.809km

Four 、 utilize geopy Library calculation

geopy It's about geocoding Python library . It mainly has the following functions ：

• Geocoding ： Convert string to geographic location .
• Reverse geocoding ： Used to convert geographic coordinates to specific addresses .
• Calculate the distance between two points ： Longitude and latitude distance and spherical distance .

pip install install geopy library , The order is ：

pip install geopy -i http://pypi.douban.com/simple --trusted-host pypi.douban.com

Python The implementation code is as follows ：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
from geopy.distance import geodesic
if __name__ == "__main__":
distance = geodesic((39.995304, 116.308264), (40.003304, 116.326759)).km
print(" distance ：{:.3f}km".format(distance))

The running results are as follows ：

 distance ：1.812km

Handwriting haversine The distance calculated by the formula is ：1.809km, And call directly geopy Library geodesic Method the calculated distance is ：1.812km, The difference between the two calculation results is very small . 

More information about geopy Use , You can learn official documents ： Welcome to use Geopy file ！ — GeoPy 2.2.0 file .

5、 ... and 、 utilize haversine library Calculation

pypi Address ：haversine · PyPI

Calculate the distance (in various units) between two points on Earth using their latitude and longitude.

Calculate the distance between two points on the earth with longitude and latitude （ Expressed in different units ）,pip install Can be installed , The order is ：

pip install haversine -i http://pypi.douban.com/simple --trusted-host pypi.douban.com

Python The implementation code is as follows ：

from haversine import haversine, Unit
if __name__ == "__main__":
# The latitude and longitude of two points
point1 = (39.995304, 116.308264)
point2 = (40.003304, 116.326759)
result1 = haversine(point1, point2, unit=Unit.KILOMETERS) # km
result2 = haversine(point1, point2, unit=Unit.METERS) # m
# Print calculation results
print(" distance ：{:.3f}km".format(result1))
print(" distance ：{:.3f}m".format(result2))

The running result is ：

 distance ：1.809km
distance ：1809.223m

You can find , utilize haversine The library calculates the distance between the result and the handwriting haversine The results calculated by the formula are consistent .