[R-sig-Geo] Extracting raster weighted mean without NAs

[Arnaud Mosnier]

You are right Pascal ... !
I was not up to date !

Thanks

Arnaud


2014-09-24 10:19 GMT-04:00 Pascal Oettli <kridox at ymail.com>:

> Hi Arnaud,
>
> It works for me with raster version 2.3-0. Please provide the output
> of sessionInfo().
>
>                 [,1]
> [1,] 2.666667
> [2,] 2.454545
>
> Regards,
> Pascal
>
> On Wed, Sep 24, 2014 at 10:59 PM, Arnaud Mosnier <a.mosnier at gmail.com>
> wrote:
> > Hi,
> >
> > I need to extract the mean value of raster values into several
> > spatialPolygons.
> > I use the extract function from the raster package with the weight option
> > in order to take into account the area of each raster cell with data
> > included into each polygon.
> > However, I want to make the calculation even if some cells contain NAs,
> >
> > Here is a small code to explain my case:
> >
> > library(raster)
> > mat <- matrix(rep(c(4,5,3,2,1), 5), ncol=5)
> > r <- raster(mat)
> > r[2,4] <- NA
> > plot(r)
> > corners1 <- rbind(c(0.2,0.1), c(0.2,0.7), c(0.4, 0.7), c(0.4,0.1),
> > c(0.2,0.1))
> > corners2 <- rbind(c(0.7,0.1), c(0.7,0.7), c(0.9, 0.7), c(0.9,0.1),
> > c(0.7,0.1))
> > polys <- SpatialPolygons(list(Polygons(list(Polygon(corners1)), ID="1"),
> > Polygons(list(Polygon(corners2)), ID="2")))
> > plot(polys, add=T)
> >
> > extract(r, polys, weight=TRUE, fun=mean, na.rm=TRUE, small=TRUE)
> >
> >>[1] 2.666667       NA
> >
> >
> >
> > Note: The use of the parameter na.rn=TRUE does not resolve my issue.
> >
> > Any workaround ?
> >
> > Thanks,
> >
> > Arnaud
> >
> >         [[alternative HTML version deleted]]
> >
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>
>
>
> --
> Pascal Oettli
> Project Scientist
> JAMSTEC
> Yokohama, Japan
>

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