[R-sig-Geo] Exporting spatstat 'pixel image' to Arcview 9.x as an e00 or ascii

[Michael Sumner]

Another way is to use the coercion methods in maptools (these are
considered additional to the basics provided by sp, since they
provider converters between classes in other packages):

library(maptools)
as(Im, "SpatialGridDataFrame")

In terms of the data the result is identical to Rolf's method, though
various attributes will not be.

Cheers, Mike.


On Tue, Jul 12, 2011 at 1:30 PM, Rolf Turner <r.turner at auckland.ac.nz> wrote:
>
> This is definitely a case of the blind leading the blind, but I thought I'd
> chip
> in anyway.
>
> Let "Im" be your pixel image.  Do:
>
> xy <- as.matrix(as.data.frame(raster.xy(as.owin(Im))))
> v <- lookup.im(Im,xy[,1],xy[,2])
> A <- SpatialPixelsDataFrame(points=xy,data=data.frame(v))
> B <- as(A,"SpatialGridDataFrame")
>
> Then "B" is an object of class "SpatialGridDataFrame" which ***may*** be
> what
> you need.  I can't really tell, since I don't understand
> SpatialGridDataFrames.
>
> The foregoing is kludgey, almost surely sub-optimal, and quite possibly
> wrong .....
> But there's a chance it will be of some use to you.
>
>    cheers,
>
>        Rolf Turner
>
> On 12/07/11 10:54, Honey-Marie de la Giroday wrote:
>>
>> Dear All,
>>
>> I have a pixel image (im) I received as a .RData file.  I need to
>> export this pixel image from R in a file format that can be imported
>> into Arcview 9.x (e.g., .e00 or ascii).
>>
>> Below is some of the code that I have been trying to use.  I have
>> reviewed the manuals for rgdal, maptools, sp, and spatstat packages
>> but have been unable to find another approach to converting the pixel
>> image to an Arcview raster dataset.  Please note that I have also
>> searched the R-sig-geo archives and was unable to find this covered
>> elsewhere.
>>
>> "#load spatst package
>> library(spatstat)
>>
>> #load file with model data
>> load(file="C:/bestmodel2004.RData")
>>
>> #Plot best model data for 2004
>> plot(bestmodel2004)
>>
>> #Examine attributes of pixel image
>> attributes(bestmodel2004)
>> $names
>>  [1] "v"      "dim"    "xrange" "yrange" "xstep"  "ystep"  "xcol"   "yrow"
>>  [9] "type"   "units"
>>
>> $class
>> [1] "im"
>>
>> #Load sp package
>> library(sp)
>>
>> #Coerce bestmodel2004 (pixel image) to SpatialGridDataFrame
>> #......how do I do this?......
>>
>> #Output to Acrview = write.asciigrid(x, fname, attr=1, na.value=-9999.....
>> #x=SpatialGridDataFrame
>> #fname=filename
>> write.asciigrid"
>>
>> Thank you for your time, and please let me know if I need to provide
>> further information.
>>
>> Sincerely,
>>
>>
>>
>> H.M.C de la Giroday
>>
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>
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-- 
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsumner at gmail.com