[R-sig-Geo] Extract multiple raster but obtain NULL values

[Robert J. Hijmans]

Diego,
To check what extract does you should look at what it returns! Your
object "rasValue" in this case.
Then it should be easy to understand that the mistake is here:

combine=cbind(points,rasValue)

You can fix it like this:

combine=cbind(coordinates(points), rasValue)
Robert


On Thu, Jul 18, 2013 at 1:36 AM, Diego Valbuena <dfvv at yahoo.com> wrote:
> Hello All,
>
> This must be a simple mistake but I'm trying to get information for few points of 10.000 raster files (TIFF) into a table. If I do it individually, I get the real values for each individual raster. But if I do it using "stack" (see below), I get the correct values only for the first raster; for the other raster files I get NULL. Would you have a suggestion to make it work (I'm using R 3.0.1)?
> Thanks, Diego
>
>
>
> library (sp)
> library (rgdal)
> library (raster)
>
> f <- list.files("folder")
>
> s <- stack(f)
>
>
> points = read.csv("points.csv")
>
> coordinates(points)= ~X+Y
>
> rasValue=extract(s, points)
>
> combine=cbind(points,rasValue)
>
>
>
>
> PS. Uploading only two raster I get this result:
>
>      points2 r19830101.1 r19830101.2
> [1,] ?       0           NULL
> [2,] ?       0           NULL
> [3,] ?       0           NULL
> [4,] ?       0           NULL
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>
>
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