HistogramInterpolator

Python script for interpolating 1D histograms in ROOT files.

Requirements

Note for CMS people @ lxplus

It almost works out of the box with recent CMMSW >= 6 distributions, the only problem is the error with dateutil.rrule import for matplotlib. The simplest solution is to get the correct package into the script directory:

 wget http://niemeyer.net/download/python-dateutil/python-dateutil-1.5.tar.gz
 tar xvvf python-dateutil-1.5.tar.gz
 cp -r ./python-dateutil-1.5/dateutil/ .
 rm -rf python-dateutil-1.5
 rm python-dateutil-1.5.tar.gz

Usage

HistogramInterpolator.py setup.json --srcroot source.root --dstroot destination.root

Json structure

The information about (existing/required) histograms is provided by means of a json setup file. Here is an example of it:

{ 
"src": 
  [ { "mass": 230.0, "name": "VBF_230" },
    { "mass": 250.0, "name": "VBF_250" },
    .....
    { "mass": 650.0, "name": "VBF_650" } ],
"dst": 
  [ { "clone": "VBF_230", "mass": 232.0, "name": "VBF_232" },
    { "clone": "VBF_230", "mass": 234.0, "name": "VBF_234" },
    ..... ]
}

It should contain two sections:

src provides information on source histograms:
- mass gives the value for the mass
- name entry is a key of the TH1 in the source root file
- file is an optional entry that gives you an alternative way to set a source file
dst contains information on histograms that should be created:
- mass gives the value for the mass, where the interpolated histogram should be produced
- name is a name of the new histogram
- clone mandatory entry that provides the prototype TH1 object in the destination file. From that object the script learns how many bins one needs in the resulting histogram.
- file is an optional entry that gives you an alternative way to set a destination file

Extra outputs

Using --plot plotname.pdf argument you are able to ask the script to make a 2D contour plot of the spline, used in interpolation. Useful when you want to see how good the interpolation is.
With the --ratejson rate.json argument the script creates anothe json file with integrals of the produced histograms. It could be useful for some batch processing.

KKostya / HistogramInterpolator