def _clockwise(self, data):
        """Determine if points are in clockwise order."""
        total = 0
        x1, y1 = data[0]
        for x, y in data[1:]:
            total += (x - x1) * (y + y1)
            x1, y1 = x, y
        x, y = data[0]
        total += (x - x1) * (y + y1)
        return total > 0
dataset/ETHPy150Open cgarrard/osgeopy-code/ospybook/ospybook/simplevectorplotter.py/SimpleVectorPlotter._clockwise/original