pyPPPETM_old.py 文件源码

def distance(self, 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 = numpy.sin(dlat/2)**2 + numpy.cos(lat1) * numpy.cos(lat2) * numpy.sin(dlon/2)**2
        c = 2 * numpy.arcsin(numpy.sqrt(a))
        km = 6371 * c
        return km