[R-sig-Geo] Selecting cells in a raster

[Robert J. Hijmans]

Hugh,
You really should not use raster[] because that will fail with large
objects, and it is not necessary. Manuel's
 forest <- cob_r == 1
is correct.
Robert

On Tue, Oct 15, 2013 at 1:29 PM, Hugh Sturrock <hughsturrock at hotmail.com> wrote:
> Hi Manuel,
> raster[] will give you a vector of the raster values so
>
> #create a new raster of the same red and extent as cob_r
> forest_raster<-cob_r
>
> # assuming forest pixels have a value of 1
> forest_raster[forest_raster[]!=1]<-0
> plot(forest_raster)
>
> Does that work?
>
> Date: Tue, 15 Oct 2013 10:49:50 -0600
> From: mspinola10 at gmail.com
> To: r-sig-geo at r-project.org
> Subject: [R-sig-Geo] Selecting cells in a raster
>
> Dear list members,
>
> I have a raster with land use data (with values from 1 to 9).  I want to
> select the cells with value 1 wich belong to forest.  How can I do that?  I
> was trying:
>
> forest <- cob_r ==1
> plot(forest)
>
> but it didn´t work
>
>> cob_r
> class       : RasterLayer
> dimensions  : 314, 236, 74104  (nrow, ncol, ncell)
> resolution  : 300, 300  (x, y)
> extent      : 447181, 517981, 1121851, 1216051  (xmin, xmax, ymin, ymax)
> coord. ref. : +proj=tmerc +lat_0=0 +lon_0=-84 +k=0.9999 +x_0=500000 +y_0=0
> +datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0
> data source : in memory
> names       : layer
> values      : 1, 9  (min, max)
>
> --
> *Manuel Spínola, Ph.D.*
> Instituto Internacional en Conservación y Manejo de Vida Silvestre
> Universidad Nacional
> Apartado 1350-3000
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> mspinola at una.ac.cr
> mspinola10 at gmail.com
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> Personal website: Lobito de río <https://sites.google.com/site/lobitoderio/>
> Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>
>
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