Agus, That is indeed because of an unintended difference between the
released version (Barry's) and the development version on R-Forge (yours). I
have fixed the development version. Thanks for pointing this out. Robert

On Fri, Jul 15, 2011 at 12:12 PM, Agustin Lobo <alobolistas@gmail.com>wrote:

> Barry,
>
> I tried that first, but by some reason (my raster version?), the
> result here is different than yours:
> > CODEQP <- raster(extent(PNMlimit))
> > show(CODEQP)
> class       : RasterLayer
> dimensions  : 10, 10, 100  (nrow, ncol, ncell)
> resolution  : 2586.382, 1886.275  (x, y)
> extent      : 438048.4, 463912.3, 4615552, 4634415  (xmin, xmax, ymin,
> ymax)
> coord. ref. : NA
> values      : none
>
> > res(CODEQP)<-c(100,100)
> > show(CODEQP)
> class       : RasterLayer
> dimensions  : 10, 10, 100  (nrow, ncol, ncell)
> resolution  : 100, 100  (x, y)
> extent      : 438048.4, 439048.4, 4633415, 4634415  (xmin, xmax, ymin,
> ymax)
> coord. ref. : NA
> values      : none
>
> Note res() keeps the same nb. of pixels and changes (a lot) the extent.
> In your example:
> > a = raster(e)
> > show(a)
> class       : RasterLayer
> dimensions  : 10, 10, 100  (nrow, ncol, ncell)
> resolution  : 320, 460  (x, y)
> extent      : 178400, 181600, 329400, 334000  (xmin, xmax, ymin, ymax)
> coord. ref. : NA
> values      : none
>
> > res(a)=c(100,100)
> > show(a)
> class       : RasterLayer
> dimensions  : 10, 10, 100  (nrow, ncol, ncell)
> resolution  : 100, 100  (x, y)
> extent      : 178400, 179400, 333000, 334000  (xmin, xmax, ymin, ymax)
> coord. ref. : NA
> values      : none
>
> Agus
>
> > sessionInfo()
> R version 2.13.1 (2011-07-08)
> Platform: i486-pc-linux-gnu (32-bit)
>
> locale:
>  [1] LC_CTYPE=en_US.UTF-8          LC_NUMERIC=C
> LC_TIME=en_US.UTF-8
>  [4] LC_COLLATE=en_US.UTF-8        LC_MONETARY=en_US.UTF-8
> LC_MESSAGES=en_US.UTF-8
>  [7] LC_PAPER=en_US.UTF-8          LC_NAME=en_US.UTF-8
> LC_ADDRESS=en_US.UTF-8
> [10] LC_TELEPHONE=en_US.UTF-8      LC_MEASUREMENT=en_US.UTF-8
> LC_IDENTIFICATION=en_US.UTF-8
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] rgdal_0.6-31  raster_1.8-42 sp_0.9-83     rkward_0.5.6
>
> loaded via a namespace (and not attached):
> [1] grid_2.13.1     lattice_0.19-30 tools_2.13.1
>
>
> Agus
>
>
> 2011/7/15 Barry Rowlingson <b.rowlingson@lancaster.ac.uk>:
> > On Fri, Jul 15, 2011 at 12:00 PM, Agustin Lobo <alobolistas@gmail.com>
> wrote:
> >> Hi!
> >>
> >> Is it possible to create a raster object using extent and resolution,
> >> thus having
> >> raster() to calculate the required nb. of rows and columns? Something
> like,
> >>
> >> a = raster (ext=miextent, res=100)
> >>
> >> (Obviously the nb. of pixels would have to be rounded)
> >
> > In two steps: create the raster and then set the resolution using "res<-"
> >
> >> e
> > class       : Extent
> > xmin        : 178400
> > xmax        : 181600
> > ymin        : 329400
> > ymax        : 334000
> >> a = raster(e); res(a)=c(100,100)
> >> a
> > class       : RasterLayer
> > dimensions  : 46, 32, 1472  (nrow, ncol, ncell)
> > resolution  : 100, 100  (x, y)
> > extent      : 178400, 181600, 329400, 334000  (xmin, xmax, ymin, ymax)
> > coord. ref. : NA
> > values      : none
> >
> > - it chooses the dimensions, rounding if necessary.
> >
> > Barry
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
>

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