Created
February 21, 2020 03:03
-
-
Save nschairer/0e288f84e8bfc37b5ca9593c15d28281 to your computer and use it in GitHub Desktop.
Function to compute distance in Miles or Kilometers between two latitude, longitude points on Earth using the Haversine formula
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
'''Haversine formula - Shortest distance between two points on a sphere | |
Steps: | |
1) Convert lat,long for two points from degrees to radians --> divide by 180/pi == 57.29577951 | |
2) Earth radius in miles -> 3958.8, Km -> 6371 | |
3) Formula | |
hav(lat2 - lat1) + cos(lat1)*cos(lat2)*hav(long2-long1) | |
hav(theta) = sin^2(theta/2) = (1 - cos(theta)) / 2 | |
Let h = hav(theta) | |
d = radius * archav(h) = 2 * radius * arcsin(sqrt(h)) | |
Refs: | |
https://en.wikipedia.org/wiki/Haversine_formula "the haversine formula and law of cosines cannot be guaranteed correct to better than 0.5%." | |
''' | |
from math import radians, cos, sin, asin, sqrt | |
def distance(coords1,coords2,unit='Miles'): | |
'''Function to find the distance between two latitude, longitude points on earth | |
Args: | |
coords1 (tuple): Tuple containing the latitude/longitude of point 1 | |
coords2 (tuple): Tuple containing the latitude/longitude of point 2 | |
unit (string): Value to switch unit of measure, default is Miles other option is Kilometers | |
Returns: | |
distance (float): Distance calculated between two points on a sphere using the haversine formula | |
''' | |
lat1 = radians(coords1[0]) | |
long1 = radians(coords1[1]) | |
lat2 = radians(coords2[0]) | |
long2 = radians(coords2[1]) | |
delta_long = long2 - long1 | |
delta_lat = lat2 - lat1 | |
#Compute haversine of two points | |
a = sin(delta_lat / 2)**2 + cos(lat1) * cos(lat2) * sin(delta_long/2)**2 | |
#Compute distance by completing the formula | |
c = 2 * asin(sqrt(a)) | |
#Select radius value for earth based on unit | |
r = 3958.8 | |
if unit == 'Kilometers': | |
r = 6371 | |
return c * r | |
if __name__ == "__main__": | |
#Philly | |
point1 = (39.952031,-75.166068) | |
#NYC | |
point2 = (40.709422,-74.006358) | |
print(distance(point1,point2),'Miles') | |
print(distance(point1,point2,unit='Kilometers'),'Kilometers') |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment