This script uses Graphviz to visualize a merger tree, using the output
from consistent-trees (
To run, enter

python <tree_data> <halo_id>

where <tree_dat> is the output from consistent_trees that is usually
named tree_0_0_0.dat and <halo_id> is the halo ID at the latest
redshift.  A list of halos that is sorted by mass with their IDs can
be found in rockstar_halos/hlists/ after running

perl myconfig.cfg

(see the README in consistent_trees for more information).

1. The red arrows in the graph show the most massive progenitor of a
   particular halo.
2. The grey boxes show the global most massive progenitor.
3. The blue filled boxes show major mergers of that global most
   massive progenitor.
4. The blue outlined boxes show any other major mergers.
5. The number below the halo ID is the virial mass in units of Msun
   (no inverse h!).