query_catalog.py 文件源码

def pairs(self, sep, dv):
        """ Generate a pair catalog
        Parameters
        ----------
        sep : Angle or Quantity
        dv : Quantity
          Offset in velocity.  Positive for projected pairs (i.e. dz > input value)

        Returns
        -------

        """
        # Checks
        if not isinstance(sep, (Angle, Quantity)):
            raise IOError("Input radius must be an Angle type, e.g. 10.*u.arcsec")
        if not isinstance(dv, (Quantity)):
            raise IOError("Input velocity must be a quantity, e.g. u.km/u.s")
        # Match
        idx, d2d, d3d = match_coordinates_sky(self.coords, self.coords, nthneighbor=2)
        close = d2d < sep
        # Cut on redshift
        if dv > 0.:  # Desire projected pairs
            zem1 = self.cat['zem'][close]
            zem2 = self.cat['zem'][idx[close]]
            dv12 = ltu.dv_from_z(zem1,zem2)
            gdz = np.abs(dv12) > dv
            # f/g and b/g
            izfg = dv12[gdz] < 0*u.km/u.s
            ID_fg = self.cat[self.idkey][close][gdz][izfg]
            ID_bg = self.cat[self.idkey][idx[close]][gdz][izfg]
        else:
            pdb.set_trace()
        # Reload
        return ID_fg, ID_bg