Python code for rhumb line

Python code for rhumb line 

import math

def rhumb_line(lon1, lat1, lon2, lat2):

    # convert degrees to radians

    lon1, lat1, lon2, lat2 = map(math.radians, [lon1, lat1, lon2, lat2])

    # difference in longitude

    dlon = lon2 - lon1

    # numerator and denominator for the rhumb line formula

    num = math.log(math.tan(lat2/2 + math.pi/4) / math.tan(lat1/2 + math.pi/4))

    denom = dlon

    # ensure that the denominator is positive or negative based on the direction

    if abs(denom) > math.pi:

        if denom > 0:

            denom = -(2 * math.pi - denom)

        else:

            denom = 2 * math.pi + denom

    # calculate the rhumb line course

    course = math.degrees(math.atan2(num, denom))

    # difference in latitude

    dlat = lat2 - lat1

    # distance along the rhumb line

    distance = abs(dlat / math.cos(math.radians(course)))

    # radius of the Earth in kilometers

    radius = 6371

    # calculate the final distance in kilometers

    distance_km = distance * radius

    return course, distance_km

You can use this function by passing in the longitude and latitude coordinates of the two points you want to find the rhumb line between. The function returns the course (in degrees) and distance (in kilometers) of the rhumb line.