tree_trimmer.py

A general ROOT tree skimmer and slimmmer.

SYNOPSIS

tree_trimmer.py [OPTIONS] file1.root [file2.root ... skim.py] [OPTIONS]

DESCRIPTION

This is a very general and configurable script for skimming (skipping events) and slimming (dropping branches) ROOT TTrees.

An example call is:

tree_trimmer.py -t mytree -b vars.txt -s skim -k 'CollectionTree,tauPerfMeta/TrigConfTree' *.root skim.py

This call would chain together TTrees named 'mytree' in all '*.root' files. Then it would turn-off the branch status of all branches in mytree, except for those listed in vars.txt, which can look something like this:

EventNumber
RunNumber
lbn
el_*

Then, it would skim mytree according to the skim(tree) function specified with the option -s, and implemented in skim.py. The additional trees specified by the option -k, would also be kept in their entirety.

The counts of all events and the events passing the skim are recorded in the first and second bins of a histogram, 'h_n_events', that is saved in each output file.

OPTIONS

-h, --help
    Prints this docstring and exits.
    
-b FILE, --branches_on_file=FILE
    When specified, FILE should be the name of a file containing branch
    names, or fnmatch patterns for branch names, one per line.
    (# comments are allowed.)  This specifies the branches that
    should be turned-on, all others are turned-off.

-B FILE, --branches_off_file=FILE
    When specified, FILE should be the name of a file containing branch
    names, or fnmatch patterns for branch names, one per line.
    (# comments are allowed.)  This specifies the branches that
    should be turned-off, even if they were turned-on in the
    branches_off_file above; good for specifying exceptions.

-k 'TREE1,DIR/TREE2,...', --keep_trees='TREE1,DIR/TREE2,...'
    Comma-separated names of additional trees (metadata, config, ...) that
    should be coppied in their entirety, in addtion to the main tree being
    skimmed.

-m NUM, --max_events=NUM
    Max number of events to run over the input trees.

-M MB, --max_tree_size=MB
    Specifies the ROOT.TTree.SetMaxTreeSize in MB.  By default, ROOT should
    make it 1900 MB.

-o FILE, --out=FILE
    Specifies the name of the output file, 'skim.root' by default.

-s FUNC, --skim=FUNC
    Specifies the name of a user-supplied skimming function, FUNC(tree),
    that should return True/False if the current entry in tree passes
    the skim.  The user should implement FUNC in a python file and provide
    it as a command-line argument.  For example, to skim for events that
    have a 20 GeV electron candidate, one could write:

        def skim(ch):
            for i_el in xrange(ch.el_n):
                if ch.el_pt[i_el] > 20000.0:
                    return True
            return False

-t NAME, --tree=NAME
    Specifies the name of the main tree to be skimmed (skipping events) and
    slimmed (dropping branches), 'tauPerf' by default.

AUTHOR

Ryan Reece ryan.reece@cern.ch

COPYRIGHT

TO DO

Optionally copy all additional objects in input files. One has to pragram support for all ROOT object types that may copy differently, and treat the main tree as a special case.
Does not work if output exceeds one file. The trees appear to be duplicated in the output files.
Progress bar?

2011-06-15

rreece/tree_trimmer