tree cdcdbbb2224b7d981c12d594e447a04ad661412f
parent 38709ff1df3c5a6d5fd37fc7a18e663b4c885b62
author Denton Gentry <dgentry@google.com> 1367035572 -0700
committer Denton Gentry <dgentry@google.com> 1367035806 -0700

Add unselect operator.

unselect removes columns from the dataset.
This is useful when columns are present merely
to provide a sort order, and should not be
present in the final graph.