[R] Data for use in maps()

[Roger Bivand]

On Mon, 16 Feb 2004, Millo Giovanni wrote:

> Dear all,
> 
> I am interested in plotting maps visualizing spatial statistics in an
> aggregated fashion, according to administrative boundaries. 
> More specifically, I have fitted a cross-section model on data regarding
> Italian "counties" (province, for Italian readers) and I would like to
> visualize residual behavior on a map, in order to have a first
> assessment of their spatial autocorrelation. I would also make some EDA
> on the spatial patterns (if any) of the regressors.
> 
> I have found the maps package (and related) and would be able to do what
> I want, e.g., for the USA, essentially by
> >map("state",fill=T,col=color)
> where color is dependent on the statistic of interest, but I still lack
> a data file for counties' boundaries in Italy. Does anybody know where
> to find one? Is there any convenient tool for converting from other
> formats? I would like to do everything in R if possible.
> 

Unfortunately, while the US government makes available a large amount of 
free map data - such as administrative boundaries, this is certainly not 
the case in Europe. Of course, administrative boundaries also change, so 
the map data source you use should match the data you are trying to map. 
At least two proprietary GIS programs distribute maps of Italian provinces 
for use in their programs (MapInfo and ArcGIS), but I believe you need a 
license to access the data - it is (unlike US data) not downloadable.

It is possible that you can use the data referenced in the RArcInfo 
contributed package, which is downloaded from:

http://www.grid.unep.ch/data/grid/gnv158.php

but these are NUTS 2 regions dating at latest from the early 1990's, and 
do not seem to be the same as the CIA Italian provinces map. 

So there are three questions:

1) finding a free (or non-free) source of boundary data appropriate for
the provinces that suit your attribute data;

2) getting that into R (and possibly projecting it);

3) plotting the map.

On 2 and 3, you may find http://sal.agecon.uiuc.edu/csiss/Rgeo/index.html 
useful, especially the sections on maps. It may be that your organisation 
has purchased suitable non-free boundary data - in which case a 
"shapefile" is probably the easiest format to ask for.

> Thanks in advance
> 
> Giovanni Millo
> R&D Dept.
> Assicurazioni Generali SpA
> Trieste, Italy

-- 
Roger Bivand
Econonic Geography Section, Department of Economics, Norwegian School of 
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen, 
Norway, voice: +47-55959355, fax: +47-55959393; Roger.Bivand at nhh.no