import numpy as np
from numpy import pi, deg2rad, cos, sin, arcsin, sqrt

def haversine(s_lat, s_lng, e_lat, e_lng):
    """
    determines the great-circle distance between two point
    on a sphere given their longitudes and latitudes
    """

    # approximate radius of earth in miles
    R = 3959.87433

    s_lat = s_lat * np.pi / 180.0
    s_lng = np.deg2rad(s_lng)
    e_lat = np.deg2rad(e_lat)
    e_lng = np.deg2rad(e_lng)

    d = (
        np.sin((e_lat - s_lat) / 2) ** 2
        + np.cos(s_lat) * np.cos(e_lat) * np.sin((e_lng - s_lng) / 2) ** 2
    )

    return 2 * R * np.arcsin(np.sqrt(d))


df['distance'] = haversine(
    df["start_lat"].values,
    df["start_long"].values,
    df["end_lat"].values,
    df["end_long"].values
)