lldist.py

from numpy import *

pi180 =  pi/180
earth_radius = 6378.137*1000
 

def lldist(lon,lat):
    
    lat = lat * pi180
    dlon = (lon[1:] - lon[:-1])*pi180 
    dlat = (lat[1:] - lat[:-1])

    a = (sin(dlat/2))**2 + cos(lat[:-1]) * cos(lat[1:]) * (sin(dlon/2))**2
    angles = lon * 0
    angles[1:] = 2 * arctan2( sqrt(a), sqrt(1-a) )
    return earth_radius * angles

def ll2dist(lon,lat):

    lat = lat * pi180
    dlon = (lon[1,:] - lon[0,:])*pi180 
    dlat = (lat[1,:] - lat[0,:])

    a = (sin(dlat/2))**2 + cos(lat[0,:]) * cos(lat[1,:]) * (sin(dlon/2))**2
    angles = 2 * arctan2( sqrt(a), sqrt(1-a) )
    return earth_radius * angles

def ll2dist2vec(lonvec1, latvec1, lonvec2, latvec2):
    """Find distance between each respective elements in two sets of vectors"""
    latvec1 = latvec1 * pi180
    latvec2 = latvec2 * pi180
    dlon = (lonvec2 - lonvec1)*pi180 
    dlat = (latvec2 - latvec1)

    a = (sin(dlat/2))**2 + cos(latvec1) * cos(latvec2) * (sin(dlon/2))**2
    angles = 2 * arctan2( sqrt(a), sqrt(1-a) )
    return earth_radius * angles