def search(self, regex):
        try:
            spec = {'$or': [{'data.content'    : {'$regex': regex, '$options': 'im'}},
                            {'data.description': {'$regex': regex, '$options': 'im'}}]}
            fields = {'_id': 0}
            cur = self.db.docs.find(spec, fields)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def demag_pos(isa, pos, icur=-1, ibeta=-1, ax=0):
    """plot demag of NC/I7/ISA7 model at rotor position
    Args:
      isa: Isa7/NC object
      pos: rotor position in degree
      icur: cur amplitude index or last index if -1
      ibeta: beta angle index or last index if -1
    """
    emag = [e for e in isa.elements if e.is_magnet()]
    demag = np.array([isa.demagnetization(e, icur, ibeta)[1]
                     for e in emag])
    for i, x in enumerate(isa.pos_el_fe_induction):
        if x >= pos/180*np.pi:
            break

    hpol = demag[:, i]
    hpol[hpol == 0] = np.nan
    _contour(ax, f'Demagnetization at Pos. {round(x/np.pi*180)}° ({isa.MAGN_TEMPERATURE} °C)',
             emag, hpol, '-H / kA/m', isa)
    logger.info("Max demagnetization %f kA/m", np.nanmax(hpol))