[R-sig-Geo] from ArcGIS GRID to .ASC

[Michael Sumner]

I tried this, and AAIGrid is not available for creation by rgdal on my 
machine. See gdalDrivers() for those available.

If you install FWTools you can use a workaround to convert the export 
externally, e.g.

 x <- readGDAL(system.file("external/test.ag", package="sp")[1])

## write to GeoTIFF
 writeGDAL(x, "mes01jan.tif",  type = "Byte")

## convert externally to AAIGrid
system("gdal_translate mes01jan.tif mes01jan.asc -of AAIGrid -ot Byte")

## check result
system("gdalinfo mes01jan.asc")

I don't believe that AAIGrid can explicitly support type Byte without 
augmentation, so I would carefully check the coercion that occurs (if 
it's actually needed).

Cheers, Mike.

milton ruser wrote:
> Dear all,
> I am reading a set of maps from ArcGRID format using rgdal and I need to
> export to ASC format.
>
> But when I try the commands below, I get an error.
>
> require(rgdal)
>
> mes01jan<-readGDAL("jan_00")
> image(mes01jan, col=topo.colors(50))  #looks find
> writeGDAL(mes01jan, "mes01jan.asc", drivername = "AAIGrid", type="Byte")
>
> Any idea?
>
> miltinho, brazil
>
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