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SAF files Treatment

This is a small library to process SAF files output by MadAnalysis 5. It provides a representation of histograms that can then be manipulated in order to produce customized plots. It relies on the Python library xml.etree.

Features

File importation

The main class is the SAFFile class, which represents the file as a whole.

Basic usage: mySAF=SAFFile(<filename>) to import a SAF file.

Note: The file is modified to have a <SAF>...</SAF> as a root if needed.

Histograms

SAFFile objects have an attribute called Histos which is a list of Histo objects representing the histograms defined in the SAF file:

mySAFFile=SAFFile("MadAnalysis5job.saf")
h=mySAFFile.Histos[0]

The following attributes are the most important:

  • Data is a list that contains the entries of the histogram
  • lbins is a list that contains the left-hand limit of each data point's bins
  • binsize is the size of the binsize, nbins is the number of bins
  • xmin and xmax are the bounds of the histogram's x-axis
  • Overflow and Underflow are the sums of weights of events right and left of the histogram bounds.
  • DataNorm is the sum of the weights over all entries of the histogram and the over- and underflow
  • Title holds the name of the histogram. At the moment this is just a string of the form selection* since SAF files do not store any meaningful titles. It should be edited by the user.

The following methods are implemented

  • Normalize takes no argument and returns a histogram normalized such that the sum of weights below, in and above the histogram evaluates to 1.
  • Algebraic operations on histograms with the same nbins, xmin and xmax: +,-,*,/ return a histogram with the operation applied bin by bin.
  • str(h) returns Histogram: <Title>, <nbins> bins in [<xmin>,<xmax>]
  • print h returns Data line by line.
  • MathematicaList takes no argument and returns a string in the format of a Mathematica list of the form {{x1,y1},...,{xN,yN}} where the xi are the left-hand limit of each bin
  • Mathematica takes no argument and returns a string in the format of a Mathematica command using ListStepPlot, which can be directly evaluated to produce a histogram.

Important note

At the moment SAFT only works out of the box with SAF files for MA5 analyses that do not contain cuts due to a parsing issue with "<" symbols inside tag texts. One needs to find them and remove them by hand in the cut descriptions in order to be able to handle cuts.

Todo list

  • Rework the nomenclature (choose capitalization rules once and for all)
  • Add a Cut class
  • Handle errors with "<" symbols in cut descriptions which cause parsing failures
  • Better handling of the data (weights, normalization, cross sections etc.)
  • Add error handling
  • Better importation procedures: find a way to get the information on the content of the histograms