[R-sig-Geo] how to go from SpatialGrid to SpatialGridDataFrame ?

[Horacio Samaniego]

Edzer,

the class is:

 > class(data.new_alb[gd.glm,])
[1] "SpatialPointsDataFrame"
attr(,"package")
[1] "sp"
 > class(data.grd)
[1] "SpatialGrid"
attr(,"package")
[1] "sp"

I use the [gd.glm,] to avoid the NA in the datasets for that  
variable. However, I get the same results when omitted
 > krige(glmpred~1,data=data.new_alb,newd=data.grd)
Error in krige(glmpred ~ 1, data = data.new_alb, newd = data.grd) :
	no direct or inherited method for function 'krige' for this call

this indicates that the problem is elsewhere.


If newdata accepts SpatialGrids will it output a SpatialGridDataFrame  
with the prediction as a dataframe of that?


Regarding the example, I am not quite sure that I understand how to  
adapt the example to my data. I have a generated a grid based on my  
grass extend, and I need the predictions from my model (idw in this  
'toy' example) to go in that grid. In the meuse.grid example, you  
have a regular grid of samples and make a grid based on that, I have  
irregular samples and need to create a continuous surface of those  
values. So, I chose to build the GridTopology from my grass location.

thanks

Horacio



On Feb 1, 2006, at 12:54 PM, Edzer J. Pebesma wrote:

A Horacio Samaniego wrote:

> I wonder how I should go from a SpatialGrid to a SpatialGridDataFrame.
>
>
Using for example the function SpatialGridDataFrame()

> I have defined a grid using the functions from the sp, gstat and  
> spgrass6 packages:
>
> G<-gmeta6()
> kk<-SpatialGrid(GridTopology(c(G$south,G$west),c(G$nsres,G$ewres),c 
> (G$rows,G$cols)),alb.proj)
>
>> str(kk)
>>
> Formal class 'SpatialGrid' [package "sp"] with 5 slots
>   ..@ grid       :Formal class 'GridTopology' [package "sp"] with 3  
> slots
>   .. .. ..@ cellcentre.offset: num [1:2] -1333373 -2356259
>   .. .. ..@ cellsize         : num [1:2] 1000 1000
>   .. .. ..@ cells.dim        : int [1:2] 2899 4615
>   ..@ grid.index : int(0)
>   ..@ coords     : num [1:2, 1:2] -1333373  1564162 -2356259  2257928
>   .. ..- attr(*, "dimnames")=List of 2
>   .. .. ..$ : NULL
>   .. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
>   ..@ bbox       : num [1:2, 1:2] -1333872 -2356759  1564662  2258428
>   .. ..- attr(*, "dimnames")=List of 2
>   .. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
>   .. .. ..$ : chr [1:2] "min" "max"
>   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
>   .. .. ..@ projargs: chr "+proj=aea +lat_1=29.75 +lat_2=45.25  
> +lat_0=37.5 +lon_0=-96 +x_0=0 +y_0=0 +no_defs +a=6378137  
> +rf=298.257222101 +towgs84=0.000,0"| __truncated__
>
> Now I try to interpolate on that grid, with no success:
> interp.vals<-idw(var1~1,data,newdata=kk)
> Error in idw(corrext ~ 1, data = data.new_alb[gd.glm, ], newdata =  
> data.grd) :
> 	no direct or inherited method for function 'idw' for this call
>
> So, I guess that I need to have a 'SpatialGridDataFrame' instead of  
> just 'SpatialGrid' as the interpolation needs to be assigned to a  
> spatial location
>
newdata can be of class SpatialGrid; probably idw fails because
of the data argument. What is the class of data.new_alb[gd.glm,] ?

> kk2<-as(kk,'SpatialGridDataFrame');
> Formal class 'SpatialGridDataFrame' [package "sp"] with 6 slots
>   ..@ data       :Formal class 'AttributeList' [package "sp"] with  
> 1 slots
>   .. .. ..@ att: list()
>   ..@ grid       :Formal class 'GridTopology' [package "sp"] with 3  
> slots
>   .. .. ..@ cellcentre.offset: num [1:2] -1333373 -2356259
>   .. .. ..@ cellsize         : num [1:2] 1000 1000
>   .. .. ..@ cells.dim        : int [1:2] 2899 4615
>   ..@ grid.index : int(0)
>   ..@ coords     : num [1:2, 1:2] -1333373  1564162 -2356259  2257928
>   .. ..- attr(*, "dimnames")=List of 2
>   .. .. ..$ : NULL
>   .. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
>   ..@ bbox       : num [1:2, 1:2] -1333872 -2356759  1564662  2258428
>   .. ..- attr(*, "dimnames")=List of 2
>   .. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
>   .. .. ..$ : chr [1:2] "min" "max"
>   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
>   .. .. ..@ projargs: chr "+proj=aea +lat_1=29.75 +lat_2=45.25  
> +lat_0=37.5 +lon_0=-96 +x_0=0 +y_0=0 +no_defs +a=6378137  
> +rf=298.257222101 +towgs84=0.000,0"| __truncated__
>
> promotes the grid to the correct class SpatialGridDataFrame but do  
> not assign to space for the variable. Is there any way to assign an  
> empty "slot" just as we would do for a data.frame?
>
> To sum.  I cant seem to be able to create a "slot" (or z dimension)  
> to hold the output of my interpolation. Is there any trick out  
> there that I am missing? Any help will be appreciated.
>
> thanks,
>
> H
>
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