h2root man page

h2root — convert PAW HBOOK files to ROOT files


h2root file.hbook file.root [compress] [tolower] [lrecl]


h2root you can use to convert your HBOOK/PAW histograms or ntuples files into ROOT files. To use this program, you type the shell script command:

h2root hbookfile rootfile

If you do not specify the second parameter, a file name is automatically generated for you. If hbookfile is of the form file.hbook, then the ROOT file will be called file.root.

This program converts HBOOK histograms into ROOT objects of the class TH1F. HBOOK profile histograms are converted into ROOT profile histograms (see class TProfile). HBOOK row-wise and column-wise ntuples are automatically converted to ROOT Trees(see TTree). Some HBOOK column-wise ntuples may not be fully converted in case one of the columns is an array with fix dimensions (eg. `var[6]') or is a multi-dimensional array.

HBOOK integer identifiers are converted into ROOT named objects by prefixing the integer identifier with the letter `h' if the identifier is a positive integer and by `h_' if it is a negative integer identifier.

In case of row-wise or column-wise ntuples, each column is converted to a branch of a Tree. Note that h2root is able to convert HBOOK files containing several levels of sub-directories. Once you have converted your file, you can look at it and draw histograms or process ntuples using the ROOT interactive module. You can also use the ROOT browser (see TBrowser) to inspect this file.

The chapter How to read a Tree explains two ways to read a Tree. ROOT includes the function TTree::MakeCode to automatically generate the code for a skeleton analysis function. With



= 1 by default (use 0 for no compression)


= 1 by default (use 0 to keep case of column names)


= 0 by default (must be specified if >8092)

See Also


The ROOT Users Guide

available from the main ROOT website:

h2root is documented fully on

Original Authors

The ROOT team (see web page above):

Rene Brun and Fons Rademakers


This manual page was written by Christian Holm Christensen <cholm@nbi.dk>, for the Debian GNU/Linux system (but may be used by others).

Referenced By

g2root(1), root(1).

Version 3 ROOT