Version 0.4 available

[Roger D. Peng]

Version 0.4 of the NMMAPSdata R package has been released. This
contains a few internal changes and includes some new data.

The biggest change for users is that R 2.0.0 (or higher) is now
required. NMMAPSdata takes advantage of a few features that are only
available in version 2.0.0 of R. Also, U.S. Census 2000 data is
available for each of the NMMAPS cities in a dataframe called
`citycensus'. This dataframe can be loaded using the data() function.

Internally, regression tests have been added to make sure future
versions of the package match older versions. Also, all code is now
"lazy-loaded" so the package should (initially) require less memory
(and load faster).

As of version 0.4 of NMMAPSdata, all NMMAPS data available on the
iHAPSS website is included in the package. There will likely not be
any major changes in future versions of the package unless there is
significant user demand.

The NMMAPSdata package can be downloaded from the iHAPSS website at
http://www.ihapss.jhsph.edu/data/NMMAPS/R/.

-roger