[Rivet] Comparing histograms and ratios of certain histograms (2D scatter plots) with data

[Raghav Kunnawalkam Elayavalli]

Hi Rivet Experts, 

I want to write an analysis compares cross section of different objects and their ratios with data. Say I have 4 cross sections, A, B, C and D defined as Histo1D and I make a set of ratios which are 
B/A, C/A and D/A and i have data points for A, B, C, D, B/A, C/A and D/A.  
Now in rivet, these ratios will be done during the finalize method where i create scatter2D plots for the ratios BRatio, CRatio and DRatio. 
          divide(A, B, BRatio);
Now when i write this analysis, i plan on taking the bins for the histogram from the data yoda file 
          A = bookHisto1D("name", refData(1, 1, 1)) something like that yeah.
My question is how do i declare the ratio plots in the analysis? can they also take the binning from the data? and another technical question is all these A,B,C,D etc... are all arrays of histograms. 
so when i declare them, im doing something like this inside the loops. 
          stringstream jetpt, raa;
	  jetpt << "Jet_pT_radbin" << r << "_centbin" << i;
	  _h_jetpT[r][i] = bookHisto1D(jetpt, _ptedges);

Cheers
Raghav