Hi,

The latter method seems good to me. I haven't found any other alternative
for this purpose.

2011/10/18 Agustin Lobo <alobolistas@gmail.com>

> Hi!
>
> Given a Sp Points DF and an Sp Polygons DF, I want to add a field of
> number of points for each polygon
> to the Sp Pol. DF table. This is what I'm doing (using objects from
> the help page for sp::overlay()
> (meuse is the Sp Points DF and srdf the Sp Pol. DF)
>
> > delme3 <- overlay(meuse,srdf)
> > delme3
>  [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
> 1 1
>  [38] 1 1 1 1 1 1 2 1 2 2 2 2 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3
> 3 3
>  [75] 3 3 3 3 3 3 3 3 2 1 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2
> 2 2
> [112] 2 2 2 2 2 2 3 2 2 2 2 2 1 2 2 2 2 1 1 2 2 1 2 2 2 2 3 3 3 3 3 3 3 3 3
> 3 3
> [149] 3 3 3 3 3 3 3
> newdata <- data.frame(srdf@data,nppoints=table(delme3))
> srdf2 <- srdf
> srdf2@data <- newdata
>
> An alternative:
> newdatap <- data.frame(meuse@data, nbp=rep(1,nrow(meuse)))
> meuse2 <- meuse
> meuse2@data <- newdatap
> delme4 <- overlay(meuse2[,13],srdf,fn=sum)
> newdata <- data.frame(srdf@data,nppoints=delme4)
> srdf2 <- srdf
> srdf2@data <- newdata
>
> I wonder if there is a better way or, best, an standard R spatial
> function doing that already.
>
> Thanks!
>
> Agus
>
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