code: def castroData_from_ipix(self, ipix, colwise=False):
          
          # pix = utils.skydir_to_pix
          if colwise:
              ipix = self._tsmap.ipix_swap_axes(ipix, colwise)
          norm_d = self._norm_vals[ipix]
          nll_d = self._nll_vals[ipix]
          return CastroData(norm_d, nll_d, self._refSpec, self._norm_type)
docs: Build a CastroData object for a particular pixel