def _prepare_templates(self, shp):
        if self._template_shp == shp:
            return
        self._template_shp = shp

        s = shp[0]
        y, x = np.mgrid[0:s, 0:s].astype(np.float)
        r = np.hypot(y - s / 2, x - s / 2)

        rs = np.linspace(1., s / 2, 7)
        ts = np.array([2, 4, 6, 8, 10, 15, 20]).astype(np.float)
        ts *= (2 / s) / 20
        self.rings = np.column_stack(np.exp(-(r - rr) ** 2 / tt ** 2).ravel()
                                     for rr, tt in product(rs, ts))
dataset/ETHPy150Open ChrisBeaumont/brut/bubbly/extractors.py/RingExtractor._prepare_templates/swapped operands of `/`