Rietveld/Profile fit R factors.
       Note that the R factor computed for Rietveld refinements
       using the extracted reflection intensity values (often
       called the Rietveld or Bragg R factor, RB) is not properly
       a profile R factor.
       pdbx_pd_proc_ls_prof_R_factor, often called Rp, is an
       unweighted fitness metric for the agreement between the
       observed and computed diffraction patterns
        Rp = sumi | Iobs(i) - Icalc(i) |
               / sumi ( Iobs(i) )
   Note that in the above equations,
   w(i) is the weight for the ith data point
   Iobs(i) is the observed intensity for the ith data
             point, sometimes referred to as yi(obs) or
             yoi.
   Icalc(i) is the computed intensity for the ith data
              point with background and other corrections
              applied to match the scale of the observed dataset,
              sometimes referred to as yi(calc) or
              yci.
   n is the total number of data points (see _refine.pdbx_pd_number_of_points)
     less the number of data points excluded from the refinement.
   p is the total number of refined parameters.