[R-sig-Geo] rasterize shape file and output as .img

[Roger Bivand]

On Fri, 3 Apr 2009, milton ruser wrote:

> Dear all,
>
> I have a set of shapefile and I need rasterized it using a collumn called
> ClassCover,
> and with the resolution of 30 meters. How can I do this on R?

Use bbox() of the SpatialPolygonDataFrame to find the extent. Create a 
GridTopology object, and overlay the polygons - possibly just with 
ClassCover - and the SpatialGrid built with the GridTopology object. This 
should yield a SpatialGridDataFrame with a single band, with NAs outside 
the polygons, and the polygon column values for raster cells where their 
centres fall inside the polygons.

> Another thing is that I need to output the raster as IMG (erdas/arcgis)
> format.

writeGDAL in rgdal.

Hope this helps,

Roger

>
> Any help are welcome.
>
> Best wishes,
>
> milton
> Brasil/Toronto
>
>> require(maptools)
>> require(sp)
>> require(rgdal)
>> todos<-readShapePoly("myshape.shp")
>> sessionInfo()
> R version 2.9.0 alpha (2009-03-26 r48224)
> i386-pc-mingw32
> locale:
> LC_COLLATE=English_Canada.1252;LC_CTYPE=English_Canada.1252;LC_MONETARY=English_Canada.1252;LC_NUMERIC=C;LC_TIME=English_Canada.1252
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> other attached packages:
> [1] rgdal_0.6-7     maptools_0.7-20 sp_0.9-32       foreign_0.8-34
> loaded via a namespace (and not attached):
> [1] grid_2.9.0      lattice_0.17-20
>
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>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no