I've been using the [R treemap package](http://cran.r-project.org/web/packages/treemap/treemap.pdf) and I have a treemap that's 2 levels deep. I want the second level labels to be printed but not the first.

Using the example in the man page:

```
tmPlot(GNI2010,
       index=c("continent", "iso3"),
       vSize="population",
       vColor="GNI",
       type="value")

```

[treemap example http://www.eecs.tufts.edu/~rveroy/stuff/GNI2010-treemap.png](http://www.eecs.tufts.edu/~rveroy/stuff/GNI2010-treemap.png)

I want to get rid of the continent labels, but retain the iso3 labels. I apologize in advance if it is in the documents but haven't found it.