pyPPPETM.py 文件源码

def distance(lon1, lat1, lon2, lat2):
    """
    Calculate the great circle distance between two points
    on the earth (specified in decimal degrees)
    """

    # convert decimal degrees to radians
    lon1 = lon1*pi/180
    lat1 = lat1*pi/180
    lon2 = lon2*pi/180
    lat2 = lat2*pi/180
    # haversine formula
    dlon = lon2 - lon1
    dlat = lat2 - lat1
    a = np.sin(dlat/2)**2 + np.cos(lat1) * np.cos(lat2) * np.sin(dlon/2)**2
    c = 2 * np.arcsin(np.sqrt(a))
    km = 6371 * c
    return km