[R-sig-Geo] block and output grid size in block kriging

[Edzer Pebesma]

On 02/10/2015 06:21 AM, subash wrote:
> Dear Edzer,
> 
> Thanks for quick reply. A question still lingering in my mind is below
> 
> In a similar lines I was using block kriging of rainfall with block size of
> 25x25Km. The output grid  chosen is 1x1Km. This is resulting in kriging
> estimate computed at 1x1Km . However, my interest is to get 25x25Km kriging
> estimate.

So, set up a prediction grid (newdata) with 1 km x 1 km, and specify
block = c(25, 25), assuming km is your distance unit - that seems to be
what you do below.

> 
> The approach I tried was setting the output grid mesh as 25Km, but this is
> wrong as the block average would be arrived from 1 point only.

I don't understand this sentence.

> 
> output.grd = expand.grid(x=seq(from=tmp$min[1],
> to=tmp$max[1],by=1),y=seq(from=tmp$min[2], to=tmp$max[2], by=1))
> coordinates(output.grd) = c("x", "y")
> gridded(output.grd) = TRUE
> 
> block_Krig = krige(stn.rain.data[,3]~1,location = ~easting+northing, data =
> stn.rain.data,newdata=output.grd,model = clim.vrmod,block=c(25,25)) 
> 
> What is that I am missing.

I don't know. For more readable code, I'd suggest:

# assume col 3 in stn.rain.data is called "prec"
coordinates(stn.rain.data) = ~easting + northing
block_Krig = krige(prec~1, stn.rain.data, output.grd, clim.vrmod,
	block = c(25,25))

> 
> 
> Thanks in advance
> Subash
> 
> 
> 
> --
> View this message in context: http://r-sig-geo.2731867.n2.nabble.com/block-and-output-grid-size-in-block-kriging-tp7587770p7587773.html
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> 
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-- 
Edzer Pebesma
Institute for Geoinformatics, University of Münster,
Heisenbergstraße 2, 48149 Münster, Germany; +49 251 83 33081
Journal of Statistical Software:   http://www.jstatsoft.org/
Computers & Geosciences: http://elsevier.com/locate/inca/398

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